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Yin, Fang-Fang

Overview:

Stereotactic radiosurgery, Stereotactic body radiation therapy, treatment planning optimization, knowledge guided radiation therapy, intensity-modulated radiation therapy, image-guided radiation therapy, oncological imaging and informatics

Positions:

Professor in Radiation Oncology

Radiation Oncology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

B.S. 1982

B.S. — Zhejiang University (China)

M.S. 1987

M.S. — Bowling Green State University

Ph.D. 1992

Ph.D. — University of Chicago

Grants:

Image-guided Dosimetry for Injectable Brachytherapy based on Elastin-like Polypeptide Nanoparticles

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Co Investigator
Start Date
August 01, 2017
End Date
July 31, 2019

A Limited-angle Intra-fractional Verification (LIVE) System for SBRT Treatments

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Co-Principal Investigator
Start Date
December 12, 2014
End Date
November 30, 2018

Assessing deformable image registration in the lung using hyperpolarized-gas MRI

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Co Investigator
Start Date
July 01, 2016
End Date
June 30, 2018

Motion Management Using 4D-MRI for Liver Cancer in Radiation Therapy

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Co-Principal Investigator
Start Date
January 11, 2013
End Date
December 31, 2016

A synchronized moving grid system to improve CBCT for IGRT and ART

Administered By
Radiation Oncology
AwardedBy
Georgia Regents University
Role
Collaborator
Start Date
August 27, 2013
End Date
March 28, 2016

Accurate, High Resolution 3D Dosimetry

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
April 09, 2004
End Date
December 31, 2013

Robotic SPECT for Biological Imaging Onboard Radiation Therapy Machines

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Co-Principal Investigator
Start Date
September 22, 2011
End Date
November 30, 2013

Cross-disciplinary Training in Medical Physics

Administered By
Duke University Medical Physics Graduate Program
AwardedBy
National Institutes of Health
Role
Associate Director
Start Date
July 01, 2007
End Date
June 30, 2013

Digital tomosynthesis: a new paradigm for radiation treatment verification

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 11, 2007
End Date
July 31, 2009
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Publications:

Biopsy of enlarging lesions after stereotactic radiosurgery for brain metastases frequently reveals radiation necrosis.

Stereotactic radiosurgery (SRS) offers excellent local control for brain metastases (BM) with low rates of toxicity. Radiation necrosis (RN) may occur after treatment and is challenging to distinguish from local recurrence (LR). We evaluated enlarging brain lesions following SRS that were subsequently biopsied to differentiate RN versus LR.This study reviewed patients receiving SRS for BM between 2008 and 2012 who underwent a biopsy for suspicion of RN versus LR on MRI. Data collection included demographics, radiation parameters, imaging findings, and post-biopsy pathology. Kaplan-Meier methods determined overall survival. Fisher's exact test assessed for association between lesion biopsy result and variables of interest.Thirty-four patients with 35 biopsied BM were included. Lesions were biopsied a median of 8.8 months after SRS. Most patients had primary lung cancer (11; 31.4%). Eleven (31.4%) biopsies were positive for LR and 24 (68.6%) showed RN only. Median overall survival was longer for patients with RN (31.0 mo) than for patients with LR (14.5 mo; P = 0.135). Time from SRS to biopsy was significantly different between RN and LR groups; 10 lesions (52.5%) biopsied ≤9 months after SRS showed LR, whereas 1 lesion (6.3%) biopsied >9 months after SRS showed LR (P = 0.004). For 16 (65.7%) lesions, management was changed or directed by the biopsy results.Stereotactic biopsy for accessible enlarging lesions after SRS appears diagnostically valuable in patients with few lesions and changes clinical management. RN should be suspected in patients with an enlarging lesion more than 9 months post-SRS.

Authors
Narloch, JL; Farber, SH; Sammons, S; McSherry, F; Herndon, JE; Hoang, JK; Yin, F-F; Sampson, JH; Fecci, PE; Blackwell, KL; Kirkpatrick, JP; Kim, GJ
MLA Citation
Narloch, JL, Farber, SH, Sammons, S, McSherry, F, Herndon, JE, Hoang, JK, Yin, F-F, Sampson, JH, Fecci, PE, Blackwell, KL, Kirkpatrick, JP, and Kim, GJ. "Biopsy of enlarging lesions after stereotactic radiosurgery for brain metastases frequently reveals radiation necrosis." Neuro-oncology 19.10 (October 2017): 1391-1397.
PMID
28472527
Source
epmc
Published In
Neuro-Oncology
Volume
19
Issue
10
Publish Date
2017
Start Page
1391
End Page
1397
DOI
10.1093/neuonc/nox090

Single fraction stereotactic radiosurgery for multiple brain metastases

Authors
Limon, D; McSherry, F; Herndon, J; Sampson, J; Fecci, P; Adamson, J; Wang, Z; Yin, F-F; Floyd, S; Kirkpatrick, J; Kim, GJ
MLA Citation
Limon, D, McSherry, F, Herndon, J, Sampson, J, Fecci, P, Adamson, J, Wang, Z, Yin, F-F, Floyd, S, Kirkpatrick, J, and Kim, GJ. "Single fraction stereotactic radiosurgery for multiple brain metastases." Advances in Radiation Oncology (September 2017).
Source
crossref
Published In
Advances in Radiation Oncology
Publish Date
2017
DOI
10.1016/j.adro.2017.09.002

Accelerated Brain DCE-MRI Using Iterative Reconstruction With Total Generalized Variation Penalty for Quantitative Pharmacokinetic Analysis: A Feasibility Study.

To investigate the feasibility of using undersampled k-space data and an iterative image reconstruction method with total generalized variation penalty in the quantitative pharmacokinetic analysis for clinical brain dynamic contrast-enhanced magnetic resonance imaging.Eight brain dynamic contrast-enhanced magnetic resonance imaging scans were retrospectively studied. Two k-space sparse sampling strategies were designed to achieve a simulated image acquisition acceleration factor of 4. They are (1) a golden ratio-optimized 32-ray radial sampling profile and (2) a Cartesian-based random sampling profile with spatiotemporal-regularized sampling density constraints. The undersampled data were reconstructed to yield images using the investigated reconstruction technique. In quantitative pharmacokinetic analysis on a voxel-by-voxel basis, the rate constant Ktrans in the extended Tofts model and blood flow FB and blood volume VB from the 2-compartment exchange model were analyzed. Finally, the quantitative pharmacokinetic parameters calculated from the undersampled data were compared with the corresponding calculated values from the fully sampled data. To quantify each parameter's accuracy calculated using the undersampled data, error in volume mean, total relative error, and cross-correlation were calculated.The pharmacokinetic parameter maps generated from the undersampled data appeared comparable to the ones generated from the original full sampling data. Within the region of interest, most derived error in volume mean values in the region of interest was about 5% or lower, and the average error in volume mean of all parameter maps generated through either sampling strategy was about 3.54%. The average total relative error value of all parameter maps in region of interest was about 0.115, and the average cross-correlation of all parameter maps in region of interest was about 0.962. All investigated pharmacokinetic parameters had no significant differences between the result from original data and the reduced sampling data.With sparsely sampled k-space data in simulation of accelerated acquisition by a factor of 4, the investigated dynamic contrast-enhanced magnetic resonance imaging pharmacokinetic parameters can accurately estimate the total generalized variation-based iterative image reconstruction method for reliable clinical application.

Authors
Wang, C; Yin, F-F; Kirkpatrick, JP; Chang, Z
MLA Citation
Wang, C, Yin, F-F, Kirkpatrick, JP, and Chang, Z. "Accelerated Brain DCE-MRI Using Iterative Reconstruction With Total Generalized Variation Penalty for Quantitative Pharmacokinetic Analysis: A Feasibility Study." Technology in cancer research & treatment 16.4 (August 2017): 446-460.
PMID
27215931
Source
epmc
Published In
Technology in cancer research & treatment
Volume
16
Issue
4
Publish Date
2017
Start Page
446
End Page
460
DOI
10.1177/1533034616649294

Respiratory signal prediction based on adaptive boosting and multi-layer perceptron neural network.

To improve the prediction accuracy of respiratory signals using adaptive boosting and multi-layer perceptron neural network (ADMLP-NN) for gated treatment of moving target in radiation therapy. The respiratory signals acquired using a real-time position management (RPM) device from 138 previous 4DCT scans were retrospectively used in this study. The ADMLP-NN was composed of several artificial neural networks (ANNs) which were used as weaker predictors to compose a stronger predictor. The respiratory signal was initially smoothed using a Savitzky-Golay finite impulse response smoothing filter (S-G filter). Then, several similar multi-layer perceptron neural networks (MLP-NNs) were configured to estimate future respiratory signal position from its previous positions. Finally, an adaptive boosting (Adaboost) decision algorithm was used to set weights for each MLP-NN based on the sample prediction error of each MLP-NN. Two prediction methods, MLP-NN and ADMLP-NN (MLP-NN plus adaptive boosting), were evaluated by calculating correlation coefficient and root-mean-square-error between true and predicted signals. For predicting 500 ms ahead of prediction, average correlation coefficients were improved from 0.83 (MLP-NN method) to 0.89 (ADMLP-NN method). The average of root-mean-square-error (relative unit) for 500 ms ahead of prediction using ADMLP-NN were reduced by 27.9%, compared to those using MLP-NN. The preliminary results demonstrate that the ADMLP-NN respiratory prediction method is more accurate than the MLP-NN method and can improve the respiration prediction accuracy.

Authors
Sun, WZ; Jiang, MY; Ren, L; Dang, J; You, T; Yin, F-F
MLA Citation
Sun, WZ, Jiang, MY, Ren, L, Dang, J, You, T, and Yin, F-F. "Respiratory signal prediction based on adaptive boosting and multi-layer perceptron neural network." Physics in medicine and biology 62.17 (August 2017): 6822-6835.
PMID
28665297
Source
epmc
Published In
Physics in Medicine and Biology
Volume
62
Issue
17
Publish Date
2017
Start Page
6822
End Page
6835
DOI
10.1088/1361-6560/aa7cd4

Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis.

To provide a benchmark for seminal vesicle (SV) margin selection to account for intrafractional motion and to investigate the effectiveness of 2 motion surrogates in predicting intrafractional SV coverage.Fifteen prostate patients were studied. Each patient had 5 pairs (1 patient had 4 pairs) of pretreatment and posttreatment cone beam CTs (CBCTs). Each pair of CBCTs was registered on the basis of prostate fiducial markers. All pretreatment SVs were expanded with 1-, 2-, 3-, 4-, 5-, and 8-mm isotropic margins to form a series of planning target volumes, and their intrafractional coverage to the posttreatment SV determined the "ground truth" for exact coverage. Two motion surrogates, the center of mass (COM) and the border of contour, were evaluated by the use of Pearson product-moment correlation coefficient and exponential fitting for predicting SV underdosage. Action threshold of each surrogate was calculated. The margin for each surrogate was calculated according to a traditional margin recipe.Ninety-five percent posttreatment SV coverage was achieved in 9%, 53%, 73%, 86%, 95%, and 97% of fractions with 1-, 2-, 3-, 4-, 5-, and 8-mm margins, respectively. The 5-mm margins provided 95% intrafractional SV coverage in over 90% of fractions. The correlation between the COM and border was weak, moderate, and strong in the left-right (L-R), anterior-posterior (A-P), and superior-inferior (S-I) directions, respectively. Exponential fitting gave the underdosage threshold of 4.5 and 7.0 mm for the COM and border. The Van Herk margin recipe recommended 0-, 0.5-, and 0.8-mm margins in the L-R, A-P, and S-I directions based on the COM, and 1.2-, 3.9-, and 2.5-mm margins based on the border.Five-millimeter isotropic margins for the SV constitute the minimum required to mitigate the intrafractional motion. Both the COM and the border are acceptable predictors for SV underdosage with 4.5- and 7.0-mm action threshold. Traditional margin based on the COM or border underestimates the margin.

Authors
Sheng, Y; Li, T; Lee, WR; Yin, F-F; Wu, QJ
MLA Citation
Sheng, Y, Li, T, Lee, WR, Yin, F-F, and Wu, QJ. "Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis." International journal of radiation oncology, biology, physics 98.2 (June 2017): 473-480.
PMID
28463167
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
98
Issue
2
Publish Date
2017
Start Page
473
End Page
480
DOI
10.1016/j.ijrobp.2017.02.089

Reducing scan angle using adaptive prior knowledge for a limited-angle intrafraction verification (LIVE) system for conformal arc radiotherapy.

The purpose of this study is to develop an adaptive prior knowledge guided image estimation technique to reduce the scan angle needed in the limited-angle intrafraction verification (LIVE) system for 4D-CBCT reconstruction. The LIVE system has been previously developed to reconstruct 4D volumetric images on-the-fly during arc treatment for intrafraction target verification and dose calculation. In this study, we developed an adaptive constrained free-form deformation reconstruction technique in LIVE to further reduce the scanning angle needed to reconstruct the 4D-CBCT images for faster intrafraction verification. This technique uses free form deformation with energy minimization to deform prior images to estimate 4D-CBCT based on kV-MV projections acquired in extremely limited angle (orthogonal 3°) during the treatment. Note that the prior images are adaptively updated using the latest CBCT images reconstructed by LIVE during treatment to utilize the continuity of the respiratory motion. The 4D digital extended-cardiac-torso (XCAT) phantom and a CIRS 008A dynamic thoracic phantom were used to evaluate the effectiveness of this technique. The reconstruction accuracy of the technique was evaluated by calculating both the center-of-mass-shift (COMS) and 3D volume-percentage-difference (VPD) of the tumor in reconstructed images and the true on-board images. The performance of the technique was also assessed with varied breathing signals against scanning angle, lesion size, lesion location, projection sampling interval, and scanning direction. In the XCAT study, using orthogonal-view of 3° kV and portal MV projections, this technique achieved an average tumor COMS/VPD of 0.4  ±  0.1 mm/5.5  ±  2.2%, 0.6  ±  0.3 mm/7.2  ±  2.8%, 0.5  ±  0.2 mm/7.1  ±  2.6%, 0.6  ±  0.2 mm/8.3  ±  2.4%, for baseline drift, amplitude variation, phase shift, and patient breathing signal variation, respectively. In the CIRS phantom study, this technique achieved an average tumor COMS/VPD of 0.7  ±  0.1 mm/7.5  ±  1.3% for a 3 cm lesion and 0.6  ±  0.2 mm/11.4  ±  1.5% for a 2 cm lesion in the baseline drift case. The average tumor COMS/VPD were 0.5  ±  0.2 mm/10.8  ±  1.4%, 0.4  ±  0.3 mm/7.3  ±  2.9%, 0.4  ±  0.2 mm/7.4  ±  2.5%, 0.4  ±  0.2 mm/7.3  ±  2.8% for the four real patient breathing signals, respectively. Results demonstrated that the adaptive prior knowledge guided image estimation technique with LIVE system is robust against scanning angle, lesion size, location and scanning direction. It can estimate on-board images accurately with as little as 6 projections in orthogonal-view 3° angle. In conclusion, adaptive prior knowledge guided image reconstruction technique accurately estimates 4D-CBCT images using extremely-limited angle and projections. This technique greatly improves the efficiency and accuracy of LIVE system for ultrafast 4D intrafraction verification of lung SBRT treatments.

Authors
Zhang, Y; Yin, F-F; Zhang, Y; Ren, L
MLA Citation
Zhang, Y, Yin, F-F, Zhang, Y, and Ren, L. "Reducing scan angle using adaptive prior knowledge for a limited-angle intrafraction verification (LIVE) system for conformal arc radiotherapy." Physics in medicine and biology 62.9 (May 2017): 3859-3882.
PMID
28338470
Source
epmc
Published In
Physics in Medicine and Biology
Volume
62
Issue
9
Publish Date
2017
Start Page
3859
End Page
3882
DOI
10.1088/1361-6560/aa6913

Quantitative Approach to Failure Mode and Effect Analysis for Linear Accelerator Quality Assurance.

To determine clinic-specific linear accelerator quality assurance (QA) TG-142 test frequencies, to maximize physicist time efficiency and patient treatment quality.A novel quantitative approach to failure mode and effect analysis is proposed. Nine linear accelerator-years of QA records provided data on failure occurrence rates. The severity of test failure was modeled by introducing corresponding errors into head and neck intensity modulated radiation therapy treatment plans. The relative risk of daily linear accelerator QA was calculated as a function of frequency of test performance.Although the failure severity was greatest for daily imaging QA (imaging vs treatment isocenter and imaging positioning/repositioning), the failure occurrence rate was greatest for output and laser testing. The composite ranking results suggest that performing output and lasers tests daily, imaging versus treatment isocenter and imaging positioning/repositioning tests weekly, and optical distance indicator and jaws versus light field tests biweekly would be acceptable for non-stereotactic radiosurgery/stereotactic body radiation therapy linear accelerators.Failure mode and effect analysis is a useful tool to determine the relative importance of QA tests from TG-142. Because there are practical time limitations on how many QA tests can be performed, this analysis highlights which tests are the most important and suggests the frequency of testing based on each test's risk priority number.

Authors
O'Daniel, JC; Yin, F-F
MLA Citation
O'Daniel, JC, and Yin, F-F. "Quantitative Approach to Failure Mode and Effect Analysis for Linear Accelerator Quality Assurance." International journal of radiation oncology, biology, physics 98.1 (May 2017): 56-62.
PMID
28587053
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
98
Issue
1
Publish Date
2017
Start Page
56
End Page
62
DOI
10.1016/j.ijrobp.2017.01.035

Retrospective four-dimensional magnetic resonance imaging with image-based respiratory surrogate: a sagittal-coronal-diaphragm point of intersection motion tracking method.

A four-dimensional magnetic resonance imaging (4-D-MRI) technique with Sagittal-Coronal-Diaphragm Point-of-Intersection (SCD-PoI) as a respiratory surrogate is proposed. To develop an image-based respiratory surrogate, the SCD-PoI motion tracking method is used for retrospective 4-D-MRI reconstruction. Single-slice sagittal MR cine was acquired at a location near the center of the diaphragmatic dome. Multiple-slice coronal MR cines were acquired for 4-D-MRI reconstruction. As a motion surrogate, the diaphragm motion was measured from the PoI among the sagittal MRI cine plane, coronal MRI cine planes, and the diaphragm surface. These points were defined as the SCD-PoI. This point is used as a one-dimensional diaphragmatic navigator in our study. The 4-D-MRI technique was evaluated on a 4-D digital extended cardiac-torso (XCAT) human phantom, a motion phantom, and seven human subjects (five healthy volunteers and two cancer patients). Motion trajectories of a selected region of interest were measured on 4-D-MRI and compared with the known XCAT motion that served as references. The mean absolute amplitude difference ([Formula: see text]) and the cross-correlation coefficient (CC) of the comparisons were determined. 4-D-MRI of the XCAT phantom demonstrated highly accurate motion information ([Formula: see text], [Formula: see text]). Motion trajectories of the motion phantom measured on 4-D-MRI matched well with the references ([Formula: see text], [Formula: see text]). 4-D-MRI of human subjects showed minimal artifacts and clearly revealed the respiratory motion of organs and tumor (mean [Formula: see text]; mean [Formula: see text]). A 4-D-MRI technique with image-based respiratory surrogate has been developed and tested on phantoms and human subjects.

Authors
Liu, Y; Yin, F-F; Czito, BG; Bashir, MR; Palta, M; Cai, J
MLA Citation
Liu, Y, Yin, F-F, Czito, BG, Bashir, MR, Palta, M, and Cai, J. "Retrospective four-dimensional magnetic resonance imaging with image-based respiratory surrogate: a sagittal-coronal-diaphragm point of intersection motion tracking method." Journal of medical imaging (Bellingham, Wash.) 4.2 (April 2017): 024007-.
PMID
28653014
Source
epmc
Published In
Journal of medical imaging (Bellingham, Wash.)
Volume
4
Issue
2
Publish Date
2017
Start Page
024007
DOI
10.1117/1.jmi.4.2.024007

Estimating 4D-CBCT from prior information and extremely limited angle projections using structural PCA and weighted free-form deformation for lung radiotherapy.

To investigate the feasibility of using structural-based principal component analysis (PCA) motion-modeling and weighted free-form deformation to estimate on-board 4D-CBCT using prior information and extremely limited angle projections for potential 4D target verification of lung radiotherapy.A technique for lung 4D-CBCT reconstruction has been previously developed using a deformation field map (DFM)-based strategy. In the previous method, each phase of the 4D-CBCT was generated by deforming a prior CT volume. The DFM was solved by a motion model extracted by a global PCA and free-form deformation (GMM-FD) technique, using a data fidelity constraint and deformation energy minimization. In this study, a new structural PCA method was developed to build a structural motion model (SMM) by accounting for potential relative motion pattern changes between different anatomical structures from simulation to treatment. The motion model extracted from planning 4DCT was divided into two structures: tumor and body excluding tumor, and the parameters of both structures were optimized together. Weighted free-form deformation (WFD) was employed afterwards to introduce flexibility in adjusting the weightings of different structures in the data fidelity constraint based on clinical interests. XCAT (computerized patient model) simulation with a 30 mm diameter lesion was simulated with various anatomical and respiratory changes from planning 4D-CT to on-board volume to evaluate the method. The estimation accuracy was evaluated by the volume percent difference (VPD)/center-of-mass-shift (COMS) between lesions in the estimated and "ground-truth" on-board 4D-CBCT. Different on-board projection acquisition scenarios and projection noise levels were simulated to investigate their effects on the estimation accuracy. The method was also evaluated against three lung patients.The SMM-WFD method achieved substantially better accuracy than the GMM-FD method for CBCT estimation using extremely small scan angles or projections. Using orthogonal 15° scanning angles, the VPD/COMS were 3.47 ± 2.94% and 0.23 ± 0.22 mm for SMM-WFD and 25.23 ± 19.01% and 2.58 ± 2.54 mm for GMM-FD among all eight XCAT scenarios. Compared to GMM-FD, SMM-WFD was more robust against reduction of the scanning angles down to orthogonal 10° with VPD/COMS of 6.21 ± 5.61% and 0.39 ± 0.49 mm, and more robust against reduction of projection numbers down to only 8 projections in total for both orthogonal-view 30° and orthogonal-view 15° scan angles. SMM-WFD method was also more robust than the GMM-FD method against increasing levels of noise in the projection images. Additionally, the SMM-WFD technique provided better tumor estimation for all three lung patients compared to the GMM-FD technique.Compared to the GMM-FD technique, the SMM-WFD technique can substantially improve the 4D-CBCT estimation accuracy using extremely small scan angles and low number of projections to provide fast low dose 4D target verification.

Authors
Harris, W; Zhang, Y; Yin, F-F; Ren, L
MLA Citation
Harris, W, Zhang, Y, Yin, F-F, and Ren, L. "Estimating 4D-CBCT from prior information and extremely limited angle projections using structural PCA and weighted free-form deformation for lung radiotherapy." Medical physics 44.3 (March 2017): 1089-1104.
PMID
28079267
Source
epmc
Published In
Medical physics
Volume
44
Issue
3
Publish Date
2017
Start Page
1089
End Page
1104
DOI
10.1002/mp.12102

Four-dimensional diffusion-weighted MR imaging (4D-DWI): a feasibility study.

Diffusion-weighted Magnetic Resonance Imaging (DWI) has been shown to be a powerful tool for cancer detection with high tumor-to-tissue contrast. This study aims to investigate the feasibility of developing a four-dimensional DWI technique (4D-DWI) for imaging respiratory motion for radiation therapy applications.Image acquisition was performed by repeatedly imaging a volume of interest (VOI) using an interleaved multislice single-shot echo-planar imaging (EPI) 2D-DWI sequence in the axial plane. Each 2D-DWI image was acquired with an intermediately low b-value (b = 500 s/mm2 ) and with diffusion-encoding gradients in x, y, and z diffusion directions. Respiratory motion was simultaneously recorded using a respiratory bellow, and the synchronized respiratory signal was used to retrospectively sort the 2D images to generate 4D-DWI. Cine MRI using steady-state free precession was also acquired as a motion reference. As a preliminary feasibility study, this technique was implemented on a 4D digital human phantom (XCAT) with a simulated pancreas tumor. The respiratory motion of the phantom was controlled by regular sinusoidal motion profile. 4D-DWI tumor motion trajectories were extracted and compared with the input breathing curve. The mean absolute amplitude differences (D) were calculated in superior-inferior (SI) direction and anterior-posterior (AP) direction. The technique was then evaluated on two healthy volunteers. Finally, the effects of 4D-DWI on apparent diffusion coefficient (ADC) measurements were investigated for hypothetical heterogeneous tumors via simulations.Tumor trajectories extracted from XCAT 4D-DWI were consistent with the input signal: the average D value was 1.9 mm (SI) and 0.4 mm (AP). The average D value was 2.6 mm (SI) and 1.7 mm (AP) for the two healthy volunteers.A 4D-DWI technique has been developed and evaluated on digital phantom and human subjects. 4D-DWI can lead to more accurate respiratory motion measurement. This has a great potential to improve the visualization and delineation of cancer tumors for radiotherapy.

Authors
Liu, Y; Zhong, X; Czito, BG; Palta, M; Bashir, MR; Dale, BM; Yin, F-F; Cai, J
MLA Citation
Liu, Y, Zhong, X, Czito, BG, Palta, M, Bashir, MR, Dale, BM, Yin, F-F, and Cai, J. "Four-dimensional diffusion-weighted MR imaging (4D-DWI): a feasibility study." Medical physics 44.2 (February 2017): 397-406.
PMID
28121369
Source
epmc
Published In
Medical physics
Volume
44
Issue
2
Publish Date
2017
Start Page
397
End Page
406
DOI
10.1002/mp.12037

Impact of moving target on measurement accuracy in 3D and 4D PET imaging-a phantom study.

The purpose of this study was to evaluate the impact of tumor motion on maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) measurements in both 3-dimensional and respiratory-correlated, 4-dimensional positron emission tomography (PET) imaging. We also evaluated the effect of implementing different attenuation correction methods in 4-dimensional PET image reconstruction on SUVmax and MTV.An anthropomorphic thorax phantom with a spherical ball as a surrogate for a tumor was used. Different types of motion were imposed on the ball to mimic a patient's breathing motion. Three-dimensional PET imaging of the phantom without tumor motion was performed and used as the reference. The ball was then set in motion with different breathing motion traces and imaged with both 3- and 4-dimensional PET methods. The clinical 4-dimensional PET imaging protocol was modified so that 3 different types of attenuation correction images were used for reconstructions: the same free-breathing computed tomography (CT) for all PET phases, the same average intensity projection CT for all PET phases, and 4-dimensional CT for phase-matched attenuation correction. Tumor SUVmax and MTV values that were measured from the moving phantom were compared with the reference values.SUVmax that was measured in 3-dimensional PET imaging was different from the reference value by 20.4% on average for the motions that were investigated; this difference decreased to 2.6% with 4-dimensional PET imaging. The measurement of MTV in 4-dimensional PET also showed a similar magnitude of reduction of deviation compared with 3-dimensional PET. Four-dimensional PET with use of phase-matched 4-dimensional CT for attenuation correction showed less variation in SUVmax and MTV among phases compared with 4-dimensional PET with free-breathing CT or average intensity projection CT for attenuation correction.Four-dimensional PET imaging reduces the impact of motion on measured SUVmax and MTV when compared with 3-dimensional PET imaging. Clinical 4-dimensional PET imaging protocols should consider phase-matched 4-dimensional CT imaging for attenuation correction to achieve more accurate measurements.

Authors
Cui, Y; Bowsher, J; Cai, J; Yin, F-F
MLA Citation
Cui, Y, Bowsher, J, Cai, J, and Yin, F-F. "Impact of moving target on measurement accuracy in 3D and 4D PET imaging-a phantom study." Advances in radiation oncology 2.1 (January 2017): 94-100.
PMID
28740918
Source
epmc
Published In
Advances in Radiation Oncology
Volume
2
Issue
1
Publish Date
2017
Start Page
94
End Page
100
DOI
10.1016/j.adro.2016.12.002

An in-house protocol for improved flood field calibration of TrueBeam FFF cine imaging.

TrueBeams equipped with the 40 × 30 cm2 Electronic Portal Imaging Devices (EPIDs) are prone to image saturation at the image center when used with flattening filter free (FFF) photon energies. While cine imaging during treatment may not saturate because the beam is attenuated by the patient, the flood field calibration is affected when the standard calibration procedure is followed. Here, we describe the hardware and protocol to achieve improved image quality for this model of TrueBeam EPID.A stainless steel filter of uniform thickness was designed to have sufficient attenuation to avoid panel saturation. The cine imaging flood field calibration was acquired with the filter in place for the FFF energies under the standard calibration geometry (SID = 150 cm). Image quality during MV cine was assessed with & without the modified flood field calibration using a low contrast resolution phantom and an anthropomorphic phantom.When the flood field is acquired without the filter in place, a pixel gain artifact is clearly present in the image center which may be mis-attributed to panel saturation in the subject image. At the image center, the artifact obscured all low contrast inserts and was also visible on the anthropomorphic phantom. Using the filter for flood field calibration eliminates the artifact.TrueBeams equipped with the 40 × 30 cm2 IDU can utilize a modified flood field calibration procedure for FFF photon energies that improves image quality for cine MV imaging.

Authors
Faught, AM; Yin, F-F; Adamson, J
MLA Citation
Faught, AM, Yin, F-F, and Adamson, J. "An in-house protocol for improved flood field calibration of TrueBeam FFF cine imaging." Journal of applied clinical medical physics 18.1 (January 2017): 265-268.
PMID
28291919
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
18
Issue
1
Publish Date
2017
Start Page
265
End Page
268
DOI
10.1002/acm2.12023

Clinical Study of Orthogonal-View Phase-Matched Digital Tomosynthesis for Lung Tumor Localization.

Compared to cone-beam computed tomography, digital tomosynthesis imaging has the benefits of shorter scanning time, less imaging dose, and better mechanical clearance for tumor localization in radiation therapy. However, for lung tumors, the localization accuracy of the conventional digital tomosynthesis technique is affected by the lack of depth information and the existence of lung tumor motion. This study investigates the clinical feasibility of using an orthogonal-view phase-matched digital tomosynthesis technique to improve the accuracy of lung tumor localization.The proposed orthogonal-view phase-matched digital tomosynthesis technique benefits from 2 major features: (1) it acquires orthogonal-view projections to improve the depth information in reconstructed digital tomosynthesis images and (2) it applies respiratory phase-matching to incorporate patient motion information into the synthesized reference digital tomosynthesis sets, which helps to improve the localization accuracy of moving lung tumors. A retrospective study enrolling 14 patients was performed to evaluate the accuracy of the orthogonal-view phase-matched digital tomosynthesis technique. Phantom studies were also performed using an anthropomorphic phantom to investigate the feasibility of using intratreatment aggregated kV and beams' eye view cine MV projections for orthogonal-view phase-matched digital tomosynthesis imaging. The localization accuracy of the orthogonal-view phase-matched digital tomosynthesis technique was compared to that of the single-view digital tomosynthesis techniques and the digital tomosynthesis techniques without phase-matching.The orthogonal-view phase-matched digital tomosynthesis technique outperforms the other digital tomosynthesis techniques in tumor localization accuracy for both the patient study and the phantom study. For the patient study, the orthogonal-view phase-matched digital tomosynthesis technique localizes the tumor to an average (± standard deviation) error of 1.8 (0.7) mm for a 30° total scan angle. For the phantom study using aggregated kV-MV projections, the orthogonal-view phase-matched digital tomosynthesis localizes the tumor to an average error within 1 mm for varying magnitudes of scan angles.The pilot clinical study shows that the orthogonal-view phase-matched digital tomosynthesis technique enables fast and accurate localization of moving lung tumors.

Authors
Zhang, Y; Ren, L; Vergalasova, I; Yin, F-F
MLA Citation
Zhang, Y, Ren, L, Vergalasova, I, and Yin, F-F. "Clinical Study of Orthogonal-View Phase-Matched Digital Tomosynthesis for Lung Tumor Localization." Technology in cancer research & treatment (January 2017): 1533034617705716-.
PMID
28449625
Source
epmc
Published In
Technology in cancer research & treatment
Publish Date
2017
Start Page
1533034617705716
DOI
10.1177/1533034617705716

Characterization of Water-Clear Polymeric Gels for Use as Radiotherapy Bolus.

Our purpose was to investigate polymeric gels for use as a highly transparent radiotherapy bolus and determine the relevant physical and dosimetric properties. We first quantified tensile properties (maximum stress, strain, and Young modulus) for various polymeric gels, along with a commercial bolus product in order to illustrate the wide variety of potential materials. For a select polymeric gel with tensile properties similar to currently used radiotherapy bolus, we also evaluated mass and electron density, effective atomic number, optical transparency, and percent depth dose in clinical megavoltage photon and electron beams. For this polymeric gel, mass density was 872 ± 12 and 896 ± 13 g/cm(3) when measured via weight/volume and computed tomography Hounsfield units, respectively. Electron density was 2.95 ± 0.04 ×10(23) electrons/cm(3). Adding fused silica (9% by weight) increases density to that of water. The ratio of the effective atomic number to that of water without and with added silica was 0.780 and 0.835 at 1 MeV, 0.767 and 0.826 at 6 MeV, and 0.746 and 0.809 at 20 MeV. Percent depth dose for 6 MV photons was within 2% of water within the first 2.5 cm and after scaling by the density coincided within 1% out to >7 cm. For 6 and 20 MeV electrons, after scaling for density D80% was within 1.3 and 1.5 mm of water, respectively. The high transparency and mechanical flexibility of polymeric gels indicate potential for use as a radiotherapy bolus; differences in density from water may be managed via either using "water equivalent thickness" or by incorporating fused silica into the material.

Authors
Adamson, JD; Cooney, T; Demehri, F; Stalnecker, A; Georgas, D; Yin, F-F; Kirkpatrick, J
MLA Citation
Adamson, JD, Cooney, T, Demehri, F, Stalnecker, A, Georgas, D, Yin, F-F, and Kirkpatrick, J. "Characterization of Water-Clear Polymeric Gels for Use as Radiotherapy Bolus." Technology in cancer research & treatment (January 2017): 1533034617710579-.
PMID
28554255
Source
epmc
Published In
Technology in cancer research & treatment
Publish Date
2017
Start Page
1533034617710579
DOI
10.1177/1533034617710579

Application of the 4D XCAT Phantoms in Biomedical Imaging and Beyond

Authors
Segars, WP; Tsui, BMW; Cai, J; Yin, F-F; Fung, GSK; Samei, E
MLA Citation
Segars, WP, Tsui, BMW, Cai, J, Yin, F-F, Fung, GSK, and Samei, E. "Application of the 4D XCAT Phantoms in Biomedical Imaging and Beyond." IEEE Transactions on Medical Imaging (2017): 1-1.
Source
crossref
Published In
IEEE Transactions on Medical Imaging
Publish Date
2017
Start Page
1
End Page
1
DOI
10.1109/TMI.2017.2738448

Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor.

This study aimed to detect the sensitivity of Delt 4 on ordinary field multileaf collimator misalignments, system misalignments, random misalignments, and misalignments caused by gravity of the multileaf collimator in stereotactic body radiation therapy.(1) Two field sizes, including 2.00 cm (X) × 6.00 cm (Y) and 7.00 cm (X) × 6.00 cm (Y), were set. The leaves of X1 and X2 in the multileaf collimator were simultaneously opened. (2) Three cases of stereotactic body radiation therapy of spinal tumor were used. The dose of the planning target volume was 1800 cGy with 3 fractions. The 4 types to be simulated included (1) the leaves of X1 and X2 in the multileaf collimator were simultaneously opened, (2) only X1 of the multileaf collimator and the unilateral leaf were opened, (3) the leaves of X1 and X2 in the multileaf collimator were randomly opened, and (4) gravity effect was simulated. The leaves of X1 and X2 in the multileaf collimator shifted to the same direction. The difference between the corresponding 3-dimensional dose distribution measured by Delt 4 and the dose distribution in the original plan made in the treatment planning system was analyzed with γ index criteria of 3.0 mm/3.0%, 2.5 mm/2.5%, 2.0 mm/2.0%, 2.5 mm/1.5%, and 1.0 mm/1.0%.(1) In the field size of 2.00 cm (X) × 6.00 cm (Y), the γ pass rate of the original was 100% with 2.5 mm/2.5% as the statistical standard. The pass rate decreased to 95.9% and 89.4% when the X1 and X2 directions of the multileaf collimator were opened within 0.3 and 0.5 mm, respectively. In the field size of 7.00 (X) cm × 6.00 (Y) cm with 1.5 mm/1.5% as the statistical standard, the pass rate of the original was 96.5%. After X1 and X2 of the multileaf collimator were opened within 0.3 mm, the pass rate decreased to lower than 95%. The pass rate was higher than 90% within the 3 mm opening. (2) For spinal tumor, the change in the planning target volume V18 under various modes calculated using treatment planning system was within 1%. However, the maximum dose deviation of the spinal cord was high. In the spinal cord with a gravity of -0.25 mm, the maximum dose deviation minimally changed and increased by 6.8% than that of the original. In the largest opening of 1.00 mm, the deviation increased by 47.7% than that of the original. Moreover, the pass rate of the original determined through Delt 4 was 100% with 3 mm/3% as the statistical standard. The pass rate was 97.5% in the 0.25 mm opening and higher than 95% in the 0.5 mm opening A, 0.25 mm opening A, whole gravity series, and 0.20 mm random opening. Moreover, the pass rate was higher than 90% with 2.0 mm/2.0% as the statistical standard in the original and in the 0.25 mm gravity. The difference in the pass rates was not statistically significant among the -0.25 mm gravity, 0.25 mm opening A, 0.20 mm random opening, and original as calculated using SPSS 11.0 software with P > .05.Different analysis standards of Delt 4 were analyzed in different field sizes to improve the detection sensitivity of the multileaf collimator position on the basis of 90% throughout rate. In stereotactic body radiation therapy of spinal tumor, the 2.0 mm/2.0% standard can reveal the dosimetric differences caused by the minor multileaf collimator position compared with the 3.0 mm/3.0% statistical standard. However, some position derivations of the misalignments that caused high dose amount to the spinal cord cannot be detected. However, some misalignments were not detected when a large number of multileaf collimator were administered into the spinal cord.

Authors
Xin-Ye, N; Ren, L; Yan, H; Yin, F-F
MLA Citation
Xin-Ye, N, Ren, L, Yan, H, and Yin, F-F. "Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor." Technology in cancer research & treatment 15.6 (December 2016): NP25-NP34.
PMID
26525748
Source
epmc
Published In
Technology in cancer research & treatment
Volume
15
Issue
6
Publish Date
2016
Start Page
NP25
End Page
NP34
DOI
10.1177/1533034615610251

Is a single isocenter sufficient for volumetric modulated arc therapy radiosurgery when multiple itracranial metastases are spatially dispersed?

Previous work demonstrated improved dosimetry of single isocenter volumetric modulated arc therapy (VMAT) of multiple intracranial targets when they are located ≤ 4cm from isocenter because of narrower multileaf collimators (MLCs). In follow-up, we sought to determine if decreasing isocenter-target distance (diso) by using 2 to 3 isocenters would improve dosimetry for spatially dispersed targets. We also investigated the effect of a maximum dose constraint during VMAT optimization, and the dosimetric effect of the number of VMAT arcs used for a larger number of targets (i.e., 7 to 9). We identified radiosurgery cases that had multiple intracranial targets with diso of at least 1 target > 5cm. A single isocenter VMAT plan was created using a standardized 4-arc technique with 18Gy per target. Each case was then replanned (1) using 2 to 3 isocenters, (2) including a maximum dose constraint per target, and in the case of 7 to 9 targets, (3) using 3 to 6 arcs. Dose evaluation included brain V6Gy and V12Gy, and conformity index (CI), gradient index (GI), and heterogeneity index (HI) per target. Two isocenters were sufficient to limit diso to ≤ 4cm and ≤ 5cm for 11/15 and 13/15 cases, respectively; after replanning with 2 to 3 isocenters, diso decreased from 5.8 ± 2.8cm (2.3 14.9) to 2.5 ± 1.4cm (0 5.2). All dose statistics improved on average, albeit modestly: V6Gy = 6.9 ± 7.1%, V12Gy = 0.9% ± 4.4%, CI = 2.6% ± 4.6%, GI = 0.9% ± 12.7%, and HI = 2.6% ± 5.2%; however, the number of arcs doubled and monitor units increase by nearly 2-fold. A maximum dose constraint had a negative effect on all dose indices, increasing V12Gy by 9.7 ± 6.9%. For ≥ 7 targets, increasing number of arcs to > 3 improved CI, V12Gy, and V6Gy. A single isocenter is likely sufficient for VMAT radiosurgery of multiple intracranial metastases. Optimal treatment plan quality is achieved when no constraint is placed on the maximum target dose; for cases with many targets at least 4 arcs are needed for optimal plan quality.

Authors
Morrison, J; Hood, R; Yin, F-F; Salama, JK; Kirkpatrick, J; Adamson, J
MLA Citation
Morrison, J, Hood, R, Yin, F-F, Salama, JK, Kirkpatrick, J, and Adamson, J. "Is a single isocenter sufficient for volumetric modulated arc therapy radiosurgery when multiple itracranial metastases are spatially dispersed?." Medical dosimetry : official journal of the American Association of Medical Dosimetrists 41.4 (December 2016): 285-289.
PMID
27614790
Source
epmc
Published In
Medical Dosimetry
Volume
41
Issue
4
Publish Date
2016
Start Page
285
End Page
289
DOI
10.1016/j.meddos.2016.06.007

A probability-based multi-cycle sorting method for 4D-MRI: A simulation study.

To develop a novel probability-based sorting method capable of generating multiple breathing cycles of 4D-MRI images and to evaluate performance of this new method by comparing with conventional phase-based methods in terms of image quality and tumor motion measurement.Based on previous findings that breathing motion probability density function (PDF) of a single breathing cycle is dramatically different from true stabilized PDF that resulted from many breathing cycles, it is expected that a probability-based sorting method capable of generating multiple breathing cycles of 4D images may capture breathing variation information missing from conventional single-cycle sorting methods. The overall idea is to identify a few main breathing cycles (and their corresponding weightings) that can best represent the main breathing patterns of the patient and then reconstruct a set of 4D images for each of the identified main breathing cycles. This method is implemented in three steps: (1) The breathing signal is decomposed into individual breathing cycles, characterized by amplitude, and period; (2) individual breathing cycles are grouped based on amplitude and period to determine the main breathing cycles. If a group contains more than 10% of all breathing cycles in a breathing signal, it is determined as a main breathing pattern group and is represented by the average of individual breathing cycles in the group; (3) for each main breathing cycle, a set of 4D images is reconstructed using a result-driven sorting method adapted from our previous study. The probability-based sorting method was first tested on 26 patients' breathing signals to evaluate its feasibility of improving target motion PDF. The new method was subsequently tested for a sequential image acquisition scheme on the 4D digital extended cardiac torso (XCAT) phantom. Performance of the probability-based and conventional sorting methods was evaluated in terms of target volume precision and accuracy as measured by the 4D images, and also the accuracy of average intensity projection (AIP) of 4D images.Probability-based sorting showed improved similarity of breathing motion PDF from 4D images to reference PDF compared to single cycle sorting, indicated by the significant increase in Dice similarity coefficient (DSC) (probability-based sorting, DSC = 0.89 ± 0.03, and single cycle sorting, DSC = 0.83 ± 0.05, p-value <0.001). Based on the simulation study on XCAT, the probability-based method outperforms the conventional phase-based methods in qualitative evaluation on motion artifacts and quantitative evaluation on tumor volume precision and accuracy and accuracy of AIP of the 4D images.In this paper the authors demonstrated the feasibility of a novel probability-based multicycle 4D image sorting method. The authors' preliminary results showed that the new method can improve the accuracy of tumor motion PDF and the AIP of 4D images, presenting potential advantages over the conventional phase-based sorting method for radiation therapy motion management.

Authors
Liang, X; Yin, F-F; Liu, Y; Cai, J
MLA Citation
Liang, X, Yin, F-F, Liu, Y, and Cai, J. "A probability-based multi-cycle sorting method for 4D-MRI: A simulation study." Medical physics 43.12 (December 2016): 6375-.
PMID
27908178
Source
epmc
Published In
Medical physics
Volume
43
Issue
12
Publish Date
2016
Start Page
6375
DOI
10.1118/1.4966705

Comparisons of volumetric modulated arc therapy (VMAT) quality assurance (QA) systems: sensitivity analysis to machine errors.

In volumetric modulated arc therapy (VMAT), gantry angles, dose rate and the MLC positions vary with the radiation delivery. The quality assurance (QA) system should be able to catch the planning and machine errors. The aim of this study was to investigate the sensitivity of three VMAT QA systems to machine errors.Several types of potential linac machine errors unique to VMAT delivery were simulated in sinusoidal function of gantry angle, including gantry angle itself, MLC position and linac output. Two commercial QA systems, ArcCheck and Delta4, and an in-house developed EPID technique were compared in this study. Fifteen full arcs from head and neck plans were selected and modified to include five magnitudes of each type of error, resulting in measurements and γ analyses of 240 arcs on each system. Both qualitative and quantitative comparisons were performed using receiver operating characteristic (ROC), γ pass rate gradient, and overlap histogram methods.In ROC analysis, the area under curve (AUC) represents the sensitivity and increases with the error magnitude. Using the criteria of 2 %/2 mm/2° (angle to agreement, ATA, only for EPID) and keeping AUC > 0.95, the minimum error detectable of ArcCheck, Delta4 and EPID are (2, 3, 3)° in gantry angle and (4, 2, 3) mm in MLC positions for the head and neck plans. No system is sensitive to the simulated output error, the AUC values were all below 0.70 even with 5 % output error. The γ gradient for gantry angle, MLC position and output errors are (-5.1, -2.6, -3.6)%/°, (-2.6, -7.1, -3.3)%/mm and (-0.2, -0.2, -0.3)%/% for ArcCheck, Delta4 and EPID, respectively. Therefore, these two analyses are consistent and support the same conclusion. The ATA parameter in EPID technique can be adjusted to tune its sensitivity.We found that ArcCheck is more sensitive to gantry angle error and Delta4 is more sensitive to MLC position error. All three systems are not sensitive to the simulated output error. With additional analysis parameter, the EPID technique can be tuned to have optimal sensitivity and is able to perform QA for full field size with highest resolution. In addition, ROC analysis avoids the choice of γ pass rate threshold and is more robust compared with other analysis methods.

Authors
Liang, B; Liu, B; Zhou, F; Yin, F-F; Wu, Q
MLA Citation
Liang, B, Liu, B, Zhou, F, Yin, F-F, and Wu, Q. "Comparisons of volumetric modulated arc therapy (VMAT) quality assurance (QA) systems: sensitivity analysis to machine errors." Radiation oncology (London, England) 11.1 (November 7, 2016): 146-.
PMID
27821135
Source
epmc
Published In
Radiation Oncology
Volume
11
Issue
1
Publish Date
2016
Start Page
146
DOI
10.1186/s13014-016-0725-4

Assessment of Treatment Response With Diffusion-Weighted MRI and Dynamic Contrast-Enhanced MRI in Patients With Early-Stage Breast Cancer Treated With Single-Dose Preoperative Radiotherapy: Initial Results.

Single-dose preoperative stereotactic body radiotherapy is a novel radiotherapy technique for the early-stage breast cancer, and the treatment response pattern of this technique needs to be investigated on a quantitative basis. In this work, dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted magnetic resonance imaging were used to study the treatment response pattern in a unique cohort of patients with early-stage breast cancer treated with preoperative radiation. Fifteen female qualified patients received single-dose preoperative radiotherapy with 1 of the 3 prescription doses: 15 Gy, 18 Gy, and 21 Gy. Magnetic resonance imaging scans including both diffusion-weighted magnetic resonance imaging and dynamic contrast-enhanced magnetic resonance imaging were acquired before radiotherapy for planning and after radiotherapy but before surgical resection. In diffusion-weighted magnetic resonance imaging, the regional averaged apparent diffusion coefficient was calculated. In dynamic contrast-enhanced magnetic resonance imaging, quantitative parameters K (trans) and v e were evaluated using the standard Tofts model based on the average contrast agent concentration within the region of interest, and the semiquantitative initial area under the concentration curve (iAUC6min) was also recorded. These parameters' relative changes after radiotherapy were calculated for gross tumor volume, clinical target volume, and planning target volume. The initial results showed that after radiotherapy, initial area under the concentration curve significantly increased in planning target volume (P < .006) and clinical target volume (P < .006), and v e significantly increased in planning target volume (P < .05) and clinical target volume (P < .05). Statistical studies suggested that linear correlations between treatment dose and the observed parameter changes exist in most examined tests, and among these tests, the change in gross tumor volume regional averaged apparent diffusion coefficient (P < .012) and between treatment dose and planning target volume K (trans) (P < .029) were found to be statistically significant. Although it is still preliminary, this pilot study may be useful to provide insights for future works.

Authors
Wang, C; Horton, JK; Yin, F-F; Chang, Z
MLA Citation
Wang, C, Horton, JK, Yin, F-F, and Chang, Z. "Assessment of Treatment Response With Diffusion-Weighted MRI and Dynamic Contrast-Enhanced MRI in Patients With Early-Stage Breast Cancer Treated With Single-Dose Preoperative Radiotherapy: Initial Results." Technology in cancer research & treatment 15.5 (October 2016): 651-660.
PMID
26134438
Source
epmc
Published In
Technology in cancer research & treatment
Volume
15
Issue
5
Publish Date
2016
Start Page
651
End Page
660
DOI
10.1177/1533034615593191

Simultaneous 4D-CBCT reconstruction with sliding motion constraint.

Current approaches using deformable vector field (DVF) for motion-compensated 4D-cone beam CT (CBCT) reconstruction typically utilize an isotropically smoothed DVF between different respiration phases. Such isotropically smoothed DVF does not work well if sliding motion exists between neighboring organs. This study investigated an anisotropic motion modeling scheme by extracting organ boundary local motions (e.g., sliding) and incorporated them into 4D-CBCT reconstruction to optimize the motion modeling and reconstruction methods.Initially, a modified simultaneous algebraic reconstruction technique (mSART) was applied to reconstruct high quality reference phase CBCT using all phase projections. The initial DVFs were precalculated and subsequently updated to achieve the optimized solution. During the DVF update, sliding motion estimation was performed by matching the measured projections to the forward projection of the deformed reference phase CBCT. In this process, each moving organ boundary was first segmented. The normal vectors of the boundary DVF were then extracted and incorporated for further DVF optimization. The regularization term in the objective function adaptively regularizes the DVF by (1) isotopically smoothing the DVF within each organ; (2) smoothing the DVF at boundary along the normal direction; and (3) leaving the tangent direction of boundary DVF unsmoothed (i.e., allowing for sliding motion). A nonlinear conjugate gradient optimizer was used. The algorithm was validated on a digital cubic tube phantom with sliding motion, nonuniform rotational B-spline based cardiac-torso (NCAT) phantom, and two anonymized patient data. The relative reconstruction error (RE), the motion trajectory's root mean square error (RMSE) together with its maximum error (MaxE), and the Dice coefficient of the lung boundary were calculated to evaluate the algorithm performance.For the cubic tube and NCAT phantom tests, the REs are 10.2% and 7.4% with sliding motion compensation, compared to 13.4% and 8.9% without sliding modeling. The motion trajectory's RMSE and MaxE for NCAT phantom tests are 0.5 and 0.8 mm with sliding motion constraint compared to 3.5 and 7.3 mm without sliding motion modeling. The Dice coefficients for both NCAT phantom and the patients show a consistent trend that sliding motion constraint achieves better similarity for segmented lung boundary compared with the ground truth or patient reference.A sliding motion-compensated 4D-CBCT reconstruction and the motion modeling scheme was developed. Both phantom and patient study demonstrated the improved accuracy and motion modeling accuracy in reconstructed 4D-CBCT.

Authors
Dang, J; Yin, F-F; You, T; Dai, C; Chen, D; Wang, J
MLA Citation
Dang, J, Yin, F-F, You, T, Dai, C, Chen, D, and Wang, J. "Simultaneous 4D-CBCT reconstruction with sliding motion constraint." Medical physics 43.10 (October 2016): 5453-.
PMID
27782722
Source
epmc
Published In
Medical physics
Volume
43
Issue
10
Publish Date
2016
Start Page
5453
DOI
10.1118/1.4959998

Re-examining TG-142 recommendations in light of modern techniques for linear accelerator based radiosurgery.

The recent development of multifocal stereotactic radiosurgery (SRS) using a single isocenter volumetric modulated arc theory (VMAT) technique warrants a re-examination of the quality assurance (QA) tolerances for routine mechanical QA recommended by the American Association of Physicists in Medicine Task Group Report Number 142. Multifocal SRS can result in targets with small volumes being at a large off-axis distance from the treatment isocenter. Consequently, angular errors in the collimator, patient support assembly (PSA), or gantry could have an increased impact on target coverage.The authors performed a retrospective analysis of dose deviations caused by systematic errors in PSA, collimator, and gantry angle at the tolerance level for routine linear accelerator QA as recommended by TG-142. Dosimetric deviations from multifocal SRS plans (N = 10) were compared to traditional single target SRS using dynamic conformal arcs (N = 10). The chief dosimetric quantities used in determining clinical impact were V100% and D99% of the individual planning target volumes and V12Gy of the healthy brain.Induced errors at tolerance levels showed the greatest change in multifocal SRS target coverage for collimator rotations (±1.0°) with the average changes to V100% and D99% being 5% and 6%, respectively, with maximum changes of 33% and 20%. A reduction in the induced error to half the TG-142 tolerance (±0.5°) demonstrated similar changes in coverage loss to traditional single target SRS assessed at the recommended tolerance level. The observed change in coverage for multifocal SRS was reduced for gantry errors (±1.0°) at 2% and 4.5% for V100% and D99%, respectively, with maximum changes of 18% and 12%. Minimal change in coverage was noted for errors in PSA rotation.This study indicates that institutions utilizing a single isocenter VMAT technique for multifocal disease should pay careful attention to the angular mechanical tolerances in designing a robust and complete QA program.

Authors
Faught, AM; Trager, M; Yin, F-F; Kirkpatrick, J; Adamson, J
MLA Citation
Faught, AM, Trager, M, Yin, F-F, Kirkpatrick, J, and Adamson, J. "Re-examining TG-142 recommendations in light of modern techniques for linear accelerator based radiosurgery." Medical physics 43.10 (October 2016): 5437-.
PMID
27782700
Source
epmc
Published In
Medical physics
Volume
43
Issue
10
Publish Date
2016
Start Page
5437
DOI
10.1118/1.4962471

Diode-based transmission detector for IMRT delivery monitoring: a validation study.

The purpose of this work was to evaluate the potential of a new transmission detector for real-time quality assurance of dynamic-MLC-based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0.7-1.2 mm). The absorption of the device was minimal (~ 1%). The increased surface dose was small (1%-9%) but, when added to existing collimator scatter effects could become significant at large field sizes (≥ 30 × 30 cm2). Overall the accuracy and speed of the device show good potential for real-time quality assurance.

Authors
Li, T; Wu, QJ; Matzen, T; Yin, F-F; O'Daniel, JC
MLA Citation
Li, T, Wu, QJ, Matzen, T, Yin, F-F, and O'Daniel, JC. "Diode-based transmission detector for IMRT delivery monitoring: a validation study." Journal of applied clinical medical physics 17.5 (September 8, 2016): 235-244.
PMID
27685115
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
17
Issue
5
Publish Date
2016
Start Page
235
End Page
244
DOI
10.1120/jacmp.v17i5.6204

Diode-based transmission detector for IMRT delivery monitoring: a validation study.

The purpose of this work was to evaluate the potential of a new transmission detector for real-time quality assurance of dynamic-MLC-based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0.7-1.2 mm). The absorption of the device was minimal (∼ 1%). The increased surface dose was small (1%-9%) but, when added to existing collimator, scatter effects could become significant at large field sizes (≥30×30 cm2). Overall the accuracy and speed of the device show good potential for real-time quality assurance. PACS number(s): 87.55.Qr.

Authors
Li, T; Wu, QJ; Matzen, T; Yin, F-F; O'Daniel, JC
MLA Citation
Li, T, Wu, QJ, Matzen, T, Yin, F-F, and O'Daniel, JC. "Diode-based transmission detector for IMRT delivery monitoring: a validation study." Journal of applied clinical medical physics 17.5 (September 2016): 1-10.
PMID
28297448
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
17
Issue
5
Publish Date
2016
Start Page
1
End Page
10
DOI
10.1120/jacmp.v17i5.6204

Evaluation of the effect of transcytolemmal water exchange analysis for therapeutic response assessment using DCE-MRI: a comparison study.

This study compares the shutter-speed (SS) and the Tofts models as used in assessing therapeutic response in a longitudinal DCE-MRI experiment. Sixteen nu/nu mice with implanted colorectal adenocarcinoma cell line (LS-174T) were randomly assigned into treatment/control groups (n  =  8/group) and received bevacizumab/saline twice weekly (Day1/Day4/Day8). All mice were scanned at one pre- (Day0) and two post-treatment (Day2/Day9) time points using a high spatiotemporal resolution DCE-MRI pulse sequence. The CA extravasation rate constant [Formula: see text] from the Tofts/SS model and the mean intracellular water residence time [Formula: see text] from the SS model were analyzed. A biological subvolume (BV) within the tumor was identified based on the [Formula: see text] intensity distribution, and the SS model parameters within the BV ([Formula: see text] and [Formula: see text]) were analyzed. It is found that [Formula: see text] and [Formula: see text] have a similar spatial distribution in the tumor volume. The Bayesian information criterion results show that the SS model was a better fit for all scans. At Day9, the treatment group had significantly higher tumor mean [Formula: see text] (p  =  0.021), [Formula: see text] (p  =  0.021) and [Formula: see text] (p  = 0.045). When BV from transcytolemmal water exchange analysis was adopted, the treatment group had higher mean [Formula: see text] at both Day2 (p  =  0.038) and Day9 (p  =  0.007). Additionally, at Day9, the treatment group had higher mean [Formula: see text] (p  =  0.045) and higher [Formula: see text] spatial heterogeneity indices (Rényi dimensions) d 1 (p  = 0.010) and d 2 (p  = 0.021). When mean [Formula: see text] and its coefficient of variation (CV) were used to separate treatment/control group samples using supporting vector machine, the accuracy of treatment/control classification was 68.8% at Day2 and 87.5% at Day9; in contrast, the Day2/Day9 accuracy were 62.5%/87.5% using tumor mean [Formula: see text] and its CV and were 50.0%/87.5% using tumor mean [Formula: see text] and its CV, respectively. These results suggest that the SS model parameters outperformed the Tofts model parameters in terms of capturing bevacizumab therapeutic effect in this longitudinal experiment.

Authors
Wang, C; Subashi, E; Liang, X; Yin, F-F; Chang, Z
MLA Citation
Wang, C, Subashi, E, Liang, X, Yin, F-F, and Chang, Z. "Evaluation of the effect of transcytolemmal water exchange analysis for therapeutic response assessment using DCE-MRI: a comparison study." Physics in medicine and biology 61.13 (July 2016): 4763-4780.
PMID
27272391
Source
epmc
Published In
Physics in Medicine and Biology
Volume
61
Issue
13
Publish Date
2016
Start Page
4763
End Page
4780
DOI
10.1088/0031-9155/61/13/4763

Scatter Reduction and Correction for Dual-Source Cone-Beam CT Using Prepatient Grids.

Scatter significantly limits the application of the dual-source cone-beam computed tomography by inducing scatter artifacts and degrading contrast-to-noise ratio, Hounsfield-unit accuracy, and image uniformity. Although our previously developed interleaved acquisition mode addressed the cross scatter between the 2 X-ray sources, it doubles the scanning time and doesn't address the forward scatter issue. This study aims to develop a prepatient grid system to address both forward scatter and cross scatter in the dual-source cone-beam computed tomography.Grids attached to both X-ray sources provide physical scatter reduction during the image acquisition. Image data were measured in the unblocked region, while both forward scatter and cross scatter were measured in the blocked region of the projection for postscan scatter correction. Complementary projections were acquired with grids at complementary locations and were merged to form complete projections for reconstruction. Experiments were conducted with different phantom sizes, grid blocking ratios, image acquisition modes, and reconstruction algorithms to investigate their effects on the scatter reduction and correction. The image quality improvement by the prepatient grids was evaluated both qualitatively through the artifact reduction and quantitatively through contrast-to-noise ratio, Hounsfield-unit accuracy, and uniformity using a CATphan 504 phantom.Scatter artifacts were reduced by scatter reduction and were removed by scatter correction method. Contrast-to-noise ratio, Hounsfield-unit accuracy, and image uniformity were improved substantially. The simultaneous acquisition mode achieved comparable contrast-to-noise ratio as the interleaved and sequential modes after scatter reduction and correction. Higher grid blocking ratio and smaller phantom size led to higher contrast-to-noise ratio for the simultaneous mode. The iterative reconstruction with total variation regularization was more effective than the Feldkamp, Davis, and Kress method in reducing noise caused by the scatter correction to enhance contrast-to-noise ratio.The prepatient grid system is effective in removing the scatter effects in the simultaneous acquisition mode of the dual-source cone-beam computed tomography, which is useful for scanning time reduction or dual energy imaging.

Authors
Ren, L; Chen, Y; Zhang, Y; Giles, W; Jin, J; Yin, F-F
MLA Citation
Ren, L, Chen, Y, Zhang, Y, Giles, W, Jin, J, and Yin, F-F. "Scatter Reduction and Correction for Dual-Source Cone-Beam CT Using Prepatient Grids." Technology in cancer research & treatment 15.3 (June 2016): 416-427.
PMID
26009495
Source
epmc
Published In
Technology in cancer research & treatment
Volume
15
Issue
3
Publish Date
2016
Start Page
416
End Page
427
DOI
10.1177/1533034615587615

A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging.

The purpose of this study was to develop a techique to generate on-board volumetric cine-magnetic resonance imaging (VC-MRI) using patient prior images, motion modeling, and on-board 2-dimensional cine MRI.One phase of a 4-dimensional MRI acquired during patient simulation is used as patient prior images. Three major respiratory deformation patterns of the patient are extracted from 4-dimensional MRI based on principal-component analysis. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI. The deformation field is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by the data fidelity constraint using the acquired on-board single 2-dimensional cine MRI. The method was evaluated using both digital extended-cardiac torso (XCAT) simulation of lung cancer patients and MRI data from 4 real liver cancer patients. The accuracy of the estimated VC-MRI was quantitatively evaluated using volume-percent-difference (VPD), center-of-mass-shift (COMS), and target tracking errors. Effects of acquisition orientation, region-of-interest (ROI) selection, patient breathing pattern change, and noise on the estimation accuracy were also evaluated.Image subtraction of ground-truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground-truth with prior image. Agreement between normalized profiles in the estimated and ground-truth VC-MRI was achieved with less than 6% error for both XCAT and patient data. Among all XCAT scenarios, the VPD between ground-truth and estimated lesion volumes was, on average, 8.43 ± 1.52% and the COMS was, on average, 0.93 ± 0.58 mm across all time steps for estimation based on the ROI region in the sagittal cine images. Matching to ROI in the sagittal view achieved better accuracy when there was substantial breathing pattern change. The technique was robust against noise levels up to SNR = 20. For patient data, average tracking errors were less than 2 mm in all directions for all patients.Preliminary studies demonstrated the feasibility of generating real-time VC-MRI for on-board localization of moving targets in radiation therapy.

Authors
Harris, W; Ren, L; Cai, J; Zhang, Y; Chang, Z; Yin, F-F
MLA Citation
Harris, W, Ren, L, Cai, J, Zhang, Y, Chang, Z, and Yin, F-F. "A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging." International journal of radiation oncology, biology, physics 95.2 (June 2016): 844-853.
PMID
27131085
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
95
Issue
2
Publish Date
2016
Start Page
844
End Page
853
DOI
10.1016/j.ijrobp.2016.02.011

Physics considerations for single-isocenter, volumetric modulated arc radiosurgery for treatment of multiple intracranial targets.

Our purpose was to address challenges associated with single-isocenter radiosurgery for multiple intracranial targets (SIRMIT) including increased sensitivity to rotational uncertainties (resulting from distance of the targets from isocenter) as well as potential for decreased plan quality from larger multileaf collimator width >4 cm from isocenter.We evaluated the effect that a 6 degrees-of-freedom couch correction had on localization uncertainty for SIRMIT using thermoplastic mask immobilization. Required setup margin was determined from rotation of the skull and mask (setup kV cone beam computed tomography relative to planning computed tomography). Intraoperational margin was determined from skull rotation within the mask (difference between pre- and posttreatment cone beam computed tomography). We also investigated 4 isocenter placement strategies: volume centroid, centroid of equally weighted points (1 per target), centroid of points weighted by inverse of volume, and Eclipse's built-in method.When no 6 degrees-of-freedom couch correction is performed after initial setup, a 0.35-mm margin is required per centimeter of target-isocenter separation to account for 95% of rotational uncertainties at initial setup. This margin is reduced to 0.10 mm/cm of target-isocenter separation to account for intraoperative rotational uncertainties when the initial setup uncertainty is eliminated via image guided 6 degrees-of-freedom couch correction. Analysis of 11 multitarget plans (37 targets) showed that conformity index and gradient index improved with decreasing distance from isocenter, this trend being more pronounced for targets <1 mL. Alternative isocenters aimed at decreasing distance of small targets improved their gradient index, but resulted in poorer dose indices for large targets. Mean distance from isocenter was smallest for the centroid of equally weighted points (4.1 ± 1.6cm vs 4.2-4.5cm).Rotational corrections via image guidance are necessary for SIRMIT with a thermoplastic mask for immobilization. There is a clear tradeoff between dosimetric quality of small and large targets that should be considered carefully when placing the isocenter.

Authors
Stanhope, C; Chang, Z; Wang, Z; Yin, F-F; Kim, G; Salama, JK; Kirkpatrick, J; Adamson, J
MLA Citation
Stanhope, C, Chang, Z, Wang, Z, Yin, F-F, Kim, G, Salama, JK, Kirkpatrick, J, and Adamson, J. "Physics considerations for single-isocenter, volumetric modulated arc radiosurgery for treatment of multiple intracranial targets." May 2016.
PMID
26723551
Source
epmc
Published In
Practical Radiation Oncology
Volume
6
Issue
3
Publish Date
2016
Start Page
207
End Page
213
DOI
10.1016/j.prro.2015.10.010

Tomosynthesis Applications in Radiation Oncology

Authors
Godfrey, DJ; Ren, L; Wu, Q; Yin, F
MLA Citation
Godfrey, DJ, Ren, L, Wu, Q, and Yin, F. "Tomosynthesis Applications in Radiation Oncology." Tomosynthesis Imaging. Taylor & Francis, April 19, 2016. (Chapter)
Source
manual
Publish Date
2016

Dynamic fractal signature dissimilarity analysis for therapeutic response assessment using dynamic contrast-enhanced MRI.

To develop a dynamic fractal signature dissimilarity (FSD) method as a novel image texture analysis technique for the quantification of tumor heterogeneity information for better therapeutic response assessment with dynamic contrast-enhanced (DCE)-MRI.A small animal antiangiogenesis drug treatment experiment was used to demonstrate the proposed method. Sixteen LS-174T implanted mice were randomly assigned into treatment and control groups (n = 8/group). All mice received bevacizumab (treatment) or saline (control) three times in two weeks, and one pretreatment and two post-treatment DCE-MRI scans were performed. In the proposed dynamic FSD method, a dynamic FSD curve was generated to characterize the heterogeneity evolution during the contrast agent uptake, and the area under FSD curve (AUCFSD) and the maximum enhancement (MEFSD) were selected as representative parameters. As for comparison, the pharmacokinetic parameter K(trans) map and area under MR intensity enhancement curve AUCMR map were calculated. Besides the tumor's mean value and coefficient of variation, the kurtosis, skewness, and classic Rényi dimensions d1 and d2 of K(trans) and AUCMR maps were evaluated for heterogeneity assessment for comparison. For post-treatment scans, the Mann-Whitney U-test was used to assess the differences of the investigated parameters between treatment/control groups. The support vector machine (SVM) was applied to classify treatment/control groups using the investigated parameters at each post-treatment scan day.The tumor mean K(trans) and its heterogeneity measurements d1 and d2 values showed significant differences between treatment/control groups in the second post-treatment scan. In contrast, the relative values (in reference to the pretreatment value) of AUCFSD and MEFSD in both post-treatment scans showed significant differences between treatment/control groups. When using AUCFSD and MEFSD as SVM input for treatment/control classification, the achieved accuracies were 93.8% and 93.8% at first and second post-treatment scan days, respectively. In comparison, the classification accuracies using d1 and d2 of K(trans) map were 87.5% and 100% at first and second post-treatment scan days, respectively.As quantitative metrics of tumor contrast agent uptake heterogeneity, the selected parameters from the dynamic FSD method accurately captured the therapeutic response in the experiment. The potential application of the proposed method is promising, and its addition to the existing DCE-MRI techniques could improve DCE-MRI performance in early assessment of treatment response.

Authors
Wang, C; Subashi, E; Yin, F-F; Chang, Z
MLA Citation
Wang, C, Subashi, E, Yin, F-F, and Chang, Z. "Dynamic fractal signature dissimilarity analysis for therapeutic response assessment using dynamic contrast-enhanced MRI." Medical physics 43.3 (March 2016): 1335-1347.
PMID
26936718
Source
epmc
Published In
Medical physics
Volume
43
Issue
3
Publish Date
2016
Start Page
1335
End Page
1347
DOI
10.1118/1.4941739

An efficient calculation method for pharmacokinetic parameters in brain permeability study using dynamic contrast-enhanced MRI.

To develop an efficient method for calculating pharmacokinetic (PK) parameters in brain DCE-MRI permeability studies.A linear least-squares fitting algorithm based on a derivative expression of the two-compartment PK model was proposed to analytically solve for the PK parameters. Noise in the expression was minimized through low-pass filtering. Simulation studies were conducted in which the proposed method was compared with two existing methods in terms of accuracy and efficiency. Five in vivo brain studies were demonstrated for potential clinical application.In the simulation studies using chosen parameter values, the calculated percent difference of K(trans) by the proposed method was <5.0% with a temporal resolution (Δt) < 5 s, and the accuracies of all parameter results were better or comparable to existing methods. When analyzed within certain parameter intensity ranges, the proposed method was more accurate than the existing methods and improved the efficiency by a factor of up to 458 for a Δt = 1 s and up to 38 for a Δt = 5 s. In the in vivo study, the calculated parameters using the proposed method were comparable to those using the existing methods with improved efficiencies.An efficient method was developed for the accurate and efficient calculation of parameters in brain DCE-MRI permeability studies.

Authors
Wang, C; Yin, F-F; Chang, Z
MLA Citation
Wang, C, Yin, F-F, and Chang, Z. "An efficient calculation method for pharmacokinetic parameters in brain permeability study using dynamic contrast-enhanced MRI." Magnetic resonance in medicine 75.2 (February 2016): 739-749.
PMID
25820381
Source
epmc
Published In
Magnetic Resonance in Medicine
Volume
75
Issue
2
Publish Date
2016
Start Page
739
End Page
749
DOI
10.1002/mrm.25659

On the sensitivity of TG-119 and IROC credentialing to TPS commissioning errors.

We investigate the sensitivity of IMRT commissioning using the TG-119 C-shape phantom and credentialing with the IROC head and neck phantom to treatment planning system commissioning errors. We introduced errors into the various aspects of the commissioning process for a 6X photon energy modeled using the analytical anisotropic algorithm within a commercial treatment planning system. Errors were implemented into the various components of the dose calculation algorithm including primary photons, secondary photons, electron contamination, and MLC parameters. For each error we evaluated the probability that it could be committed unknowingly during the dose algorithm commissioning stage, and the probability of it being identified during the verification stage. The clinical impact of each commissioning error was evaluated using representative IMRT plans including low and intermediate risk prostate, head and neck, mesothelioma, and scalp; the sensitivity of the TG-119 and IROC phantoms was evaluated by comparing dosimetric changes to the dose planes where film measurements occur and change in point doses where dosimeter measurements occur. No commissioning errors were found to have both a low probability of detection and high clinical severity. When errors do occur, the IROC credentialing and TG 119 commissioning criteria are generally effective at detecting them; however, for the IROC phantom, OAR point-dose measurements are the most sensitive despite being currently excluded from IROC analysis. Point-dose measurements with an absolute dose constraint were the most effective at detecting errors, while film analysis using a gamma comparison and the IROC film distance to agreement criteria were less effective at detecting the specific commissioning errors implemented here.

Authors
McVicker, D; Yin, F-F; Adamson, JD
MLA Citation
McVicker, D, Yin, F-F, and Adamson, JD. "On the sensitivity of TG-119 and IROC credentialing to TPS commissioning errors." Journal of applied clinical medical physics 17.1 (January 8, 2016): 34-48.
PMID
26894330
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
17
Issue
1
Publish Date
2016
Start Page
34
End Page
48
DOI
10.1120/jacmp.v17i1.5452

Accuracy of respiratory motion measurement of 4D-MRI: A comparison between cine and sequential acquisition.

The authors have recently developed a cine-mode T2*/T1-weighted 4D-MRI technique and a sequential-mode T2-weighted 4D-MRI technique for imaging respiratory motion. This study aims at investigating which 4D-MRI image acquisition mode, cine or sequential, provides more accurate measurement of organ motion during respiration.A 4D digital extended cardiac-torso (XCAT) human phantom with a hypothesized tumor was used to simulate the image acquisition and the 4D-MRI reconstruction. The respiratory motion was controlled by the given breathing signal profiles. The tumor was manipulated to move continuously with the surrounding tissue. The motion trajectories were measured from both sequential- and cine-mode 4D-MRI images. The measured trajectories were compared with the average trajectory calculated from the input profiles, which was used as references. The error in 4D-MRI tumor motion trajectory (E) was determined. In addition, the corresponding respiratory motion amplitudes of all the selected 2D images for 4D reconstruction were recorded. Each of the amplitude was compared with the amplitude of its associated bin on the average breathing curve. The mean differences from the average breathing curve across all slice positions (D) were calculated. A total of 500 simulated respiratory profiles with a wide range of irregularity (Ir) were used to investigate the relationship between D and Ir. Furthermore, statistical analysis of E and D using XCAT controlled by 20 cancer patients' breathing profiles was conducted. Wilcoxon Signed Rank test was conducted to compare two modes.D increased faster for cine-mode (D = 1.17 × Ir + 0.23) than sequential-mode (D = 0.47 × Ir + 0.23) as irregularity increased. For the XCAT study using 20 cancer patients' breathing profiles, the median E values were significantly different: 0.12 and 0.10 cm for cine- and sequential-modes, respectively, with a p-value of 0.02. The median D values were significantly different: 0.47 and 0.24 cm for cine- and sequential-modes, respectively, with a p-value < 0.001.Respiratory motion measurement may be more accurate and less susceptible to breathing irregularity in sequential-mode 4D-MRI than that in cine-mode 4D-MRI.

Authors
Liu, Y; Yin, F-F; Rhee, D; Cai, J
MLA Citation
Liu, Y, Yin, F-F, Rhee, D, and Cai, J. "Accuracy of respiratory motion measurement of 4D-MRI: A comparison between cine and sequential acquisition." Medical physics 43.1 (January 2016): 179-.
PMID
26745910
Source
epmc
Published In
Medical physics
Volume
43
Issue
1
Publish Date
2016
Start Page
179
DOI
10.1118/1.4938066

On the sensitivity of TG-119 and IROC credentialing to TPS commissioning errors.

We investigate the sensitivity of IMRT commissioning using the TG-119 C-shape phantom and credentialing with the IROC head and neck phantom to treatment planning system commissioning errors. We introduced errors into the various aspects of the commissioning process for a 6X photon energy modeled using the analytical anisotropic algorithm within a commercial treatment planning system. Errors were implemented into the various components of the dose calculation algorithm including primary photons, secondary photons, electron contamination, and MLC parameters. For each error we evaluated the probability that it could be committed unknowingly during the dose algorithm commissioning stage, and the probability of it being identified during the verification stage. The clinical impact of each commissioning error was evaluated using representative IMRT plans including low and intermediate risk prostate, head and neck, mesothelioma, and scalp; the sensitivity of the TG-119 and IROC phantoms was evaluated by comparing dosimetric changes to the dose planes where film measurements occur and change in point doses where dosimeter measurements occur. No commissioning errors were found to have both a low probability of detection and high clinical severity. When errors do occur, the IROC credentialing and TG 119 commissioning criteria are generally effective at detecting them; however, for the IROC phantom, OAR point-dose measurements are the most sensitive despite being currently excluded from IROC analysis. Point-dose measurements with an absolute dose constraint were the most effective at detecting errors, while film analysis using a gamma comparison and the IROC film distance to agreement criteria were less effective at detecting the specific commissioning errors implemented here. PACS number: 87.55.Qr.

Authors
McVicker, D; Yin, F-F; Adamson, JD
MLA Citation
McVicker, D, Yin, F-F, and Adamson, JD. "On the sensitivity of TG-119 and IROC credentialing to TPS commissioning errors." Journal of applied clinical medical physics 17.1 (January 2016): 34-48.
PMID
28297489
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
17
Issue
1
Publish Date
2016
Start Page
34
End Page
48
DOI
10.1120/jacmp.v17i1.5452

Novel Technologies for Improved Treatment Outcome and Patient Safety in Cancer Radiotherapy.

Authors
Deng, J; Feng, Y; Ma, C; Yin, F-F
MLA Citation
Deng, J, Feng, Y, Ma, C, and Yin, F-F. "Novel Technologies for Improved Treatment Outcome and Patient Safety in Cancer Radiotherapy." BioMed Research International 2016 (January 2016): 3016454-.
PMID
27034929
Source
epmc
Published In
BioMed Research International
Volume
2016
Publish Date
2016
Start Page
3016454
DOI
10.1155/2016/3016454

Atlas-guided prostate intensity modulated radiation therapy (IMRT) planning.

An atlas-based IMRT planning technique for prostate cancer was developed and evaluated. A multi-dose atlas was built based on the anatomy patterns of the patients, more specifically, the percent distance to the prostate and the concaveness angle formed by the seminal vesicles relative to the anterior-posterior axis. A 70-case dataset was classified using a k-medoids clustering analysis to recognize anatomy pattern variations in the dataset. The best classification, defined by the number of classes or medoids, was determined by the largest value of the average silhouette width. Reference plans from each class formed a multi-dose atlas. The atlas-guided planning (AGP) technique started with matching the new case anatomy pattern to one of the reference cases in the atlas; then a deformable registration between the atlas and new case anatomies transferred the dose from the atlas to the new case to guide inverse planning with full automation. 20 additional clinical cases were re-planned to evaluate the AGP technique. Dosimetric properties between AGP and clinical plans were evaluated. The classification analysis determined that the 5-case atlas would best represent anatomy patterns for the patient cohort. AGP took approximately 1 min on average (corresponding to 70 iterations of optimization) for all cases. When dosimetric parameters were compared, the differences between AGP and clinical plans were less than 3.5%, albeit some statistical significances observed: homogeneity index (p  >  0.05), conformity index (p  <  0.01), bladder gEUD (p  <  0.01), and rectum gEUD (p  =  0.02). Atlas-guided treatment planning is feasible and efficient. Atlas predicted dose can effectively guide the optimizer to achieve plan quality comparable to that of clinical plans.

Authors
Sheng, Y; Li, T; Zhang, Y; Lee, WR; Yin, F-F; Ge, Y; Wu, QJ
MLA Citation
Sheng, Y, Li, T, Zhang, Y, Lee, WR, Yin, F-F, Ge, Y, and Wu, QJ. "Atlas-guided prostate intensity modulated radiation therapy (IMRT) planning." Physics in medicine and biology 60.18 (September 8, 2015): 7277-7291.
PMID
26348663
Source
epmc
Published In
Physics in Medicine and Biology
Volume
60
Issue
18
Publish Date
2015
Start Page
7277
End Page
7291
DOI
10.1088/0031-9155/60/18/7277

T2-weighted four dimensional magnetic resonance imaging with result-driven phase sorting.

T2-weighted MRI provides excellent tumor-to-tissue contrast for target volume delineation in radiation therapy treatment planning. This study aims at developing a novel T2-weighted retrospective four dimensional magnetic resonance imaging (4D-MRI) phase sorting technique for imaging organ/tumor respiratory motion.A 2D fast T2-weighted half-Fourier acquisition single-shot turbo spin-echo MR sequence was used for image acquisition of 4D-MRI, with a frame rate of 2-3 frames/s. Respiratory motion was measured using an external breathing monitoring device. A phase sorting method was developed to sort the images by their corresponding respiratory phases. Besides, a result-driven strategy was applied to effectively utilize redundant images in the case when multiple images were allocated to a bin. This strategy, selecting the image with minimal amplitude error, will generate the most representative 4D-MRI. Since we are using a different image acquisition mode for 4D imaging (the sequential image acquisition scheme) with the conventionally used cine or helical image acquisition scheme, the 4D dataset sufficient condition was not obviously and directly predictable. An important challenge of the proposed technique was to determine the number of repeated scans (NR) required to obtain sufficient phase information at each slice position. To tackle this challenge, the authors first conducted computer simulations using real-time position management respiratory signals of the 29 cancer patients under an IRB-approved retrospective study to derive the relationships between NR and the following factors: number of slices (NS), number of 4D-MRI respiratory bins (NB), and starting phase at image acquisition (P0). To validate the authors' technique, 4D-MRI acquisition and reconstruction were simulated on a 4D digital extended cardiac-torso (XCAT) human phantom using simulation derived parameters. Twelve healthy volunteers were involved in an IRB-approved study to investigate the feasibility of this technique.4D data acquisition completeness (Cp) increases as NR increases in an inverse-exponential fashion (Cp = 100 - 99 × exp(-0.18 × NR), when NB = 6, fitted using 29 patients' data). The NR required for 4D-MRI reconstruction (defined as achieving 95% completeness, Cp = 95%, NR = NR,95) is proportional to NB (NR,95 ∼ 2.86 × NB, r = 1.0), but independent of NS and P0. Simulated XCAT 4D-MRI showed a clear pattern of respiratory motion. Tumor motion trajectories measured on 4D-MRI were comparable to the average input signal, with a mean relative amplitude error of 2.7% ± 2.9%. Reconstructed 4D-MRI for healthy volunteers illustrated clear respiratory motion on three orthogonal planes, with minimal image artifacts. The artifacts were presumably caused by breathing irregularity and incompleteness of data acquisition (95% acquired only). The mean relative amplitude error between critical structure trajectory and average breathing curve for 12 healthy volunteers is 2.5 ± 0.3 mm in superior-inferior direction.A novel T2-weighted retrospective phase sorting 4D-MRI technique has been developed and successfully applied on digital phantom and healthy volunteers.

Authors
Liu, Y; Yin, F-F; Czito, BG; Bashir, MR; Cai, J
MLA Citation
Liu, Y, Yin, F-F, Czito, BG, Bashir, MR, and Cai, J. "T2-weighted four dimensional magnetic resonance imaging with result-driven phase sorting." Medical physics 42.8 (August 2015): 4460-4471.
PMID
26233176
Source
epmc
Published In
Medical physics
Volume
42
Issue
8
Publish Date
2015
Start Page
4460
End Page
4471
DOI
10.1118/1.4923168

Dosimetric verification of lung cancer treatment using the CBCTs estimated from limited-angle on-board projections.

Lung cancer treatment is susceptible to treatment errors caused by interfractional anatomical and respirational variations of the patient. On-board treatment dose verification is especially critical for the lung stereotactic body radiation therapy due to its high fractional dose. This study investigates the feasibility of using cone-beam (CB)CT images estimated by a motion modeling and free-form deformation (MM-FD) technique for on-board dose verification.Both digital and physical phantom studies were performed. Various interfractional variations featuring patient motion pattern change, tumor size change, and tumor average position change were simulated from planning CT to on-board images. The doses calculated on the planning CT (planned doses), the on-board CBCT estimated by MM-FD (MM-FD doses), and the on-board CBCT reconstructed by the conventional Feldkamp-Davis-Kress (FDK) algorithm (FDK doses) were compared to the on-board dose calculated on the "gold-standard" on-board images (gold-standard doses). The absolute deviations of minimum dose (ΔDmin), maximum dose (ΔDmax), and mean dose (ΔDmean), and the absolute deviations of prescription dose coverage (ΔV100%) were evaluated for the planning target volume (PTV). In addition, 4D on-board treatment dose accumulations were performed using 4D-CBCT images estimated by MM-FD in the physical phantom study. The accumulated doses were compared to those measured using optically stimulated luminescence (OSL) detectors and radiochromic films.Compared with the planned doses and the FDK doses, the MM-FD doses matched much better with the gold-standard doses. For the digital phantom study, the average (± standard deviation) ΔDmin, ΔDmax, ΔDmean, and ΔV100% (values normalized by the prescription dose or the total PTV) between the planned and the gold-standard PTV doses were 32.9% (±28.6%), 3.0% (±2.9%), 3.8% (±4.0%), and 15.4% (±12.4%), respectively. The corresponding values of FDK PTV doses were 1.6% (±1.9%), 1.2% (±0.6%), 2.2% (±0.8%), and 17.4% (±15.3%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.3% (±0.2%), 0.9% (±0.6%), 0.6% (±0.4%), and 1.0% (±0.8%), respectively. Similarly, for the physical phantom study, the average ΔDmin, ΔDmax, ΔDmean, and ΔV100% of planned PTV doses were 38.1% (±30.8%), 3.5% (±5.1%), 3.0% (±2.6%), and 8.8% (±8.0%), respectively. The corresponding values of FDK PTV doses were 5.8% (±4.5%), 1.6% (±1.6%), 2.0% (±0.9%), and 9.3% (±10.5%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.4% (±0.8%), 0.8% (±1.0%), 0.5% (±0.4%), and 0.8% (±0.8%), respectively. For the 4D dose accumulation study, the average (± standard deviation) absolute dose deviation (normalized by local doses) between the accumulated doses and the OSL measured doses was 3.3% (±2.7%). The average gamma index (3%/3 mm) between the accumulated doses and the radiochromic film measured doses was 94.5% (±2.5%).MM-FD estimated 4D-CBCT enables accurate on-board dose calculation and accumulation for lung radiation therapy. It can potentially be valuable for treatment quality assessment and adaptive radiation therapy.

Authors
Zhang, Y; Yin, F-F; Ren, L
MLA Citation
Zhang, Y, Yin, F-F, and Ren, L. "Dosimetric verification of lung cancer treatment using the CBCTs estimated from limited-angle on-board projections." Medical physics 42.8 (August 2015): 4783-4795.
PMID
26233206
Source
epmc
Published In
Medical physics
Volume
42
Issue
8
Publish Date
2015
Start Page
4783
End Page
4795
DOI
10.1118/1.4926559

Utilizing knowledge from prior plans in the evaluation of quality assurance.

Increased interest regarding sensitivity of pre-treatment intensity modulated radiotherapy and volumetric modulated arc radiotherapy (VMAT) quality assurance (QA) to delivery errors has led to the development of dose-volume histogram (DVH) based analysis. This paradigm shift necessitates a change in the acceptance criteria and action tolerance for QA. Here we present a knowledge based technique to objectively quantify degradations in DVH for prostate radiotherapy. Using machine learning, organ-at-risk (OAR) DVHs from a population of 198 prior patients' plans were adapted to a test patient's anatomy to establish patient-specific DVH ranges. This technique was applied to single arc prostate VMAT plans to evaluate various simulated delivery errors: systematic single leaf offsets, systematic leaf bank offsets, random normally distributed leaf fluctuations, systematic lag in gantry angle of the mutli-leaf collimators (MLCs), fluctuations in dose rate, and delivery of each VMAT arc with a constant rather than variable dose rate.Quantitative Analyses of Normal Tissue Effects in the Clinic suggests V75Gy dose limits of 15% for the rectum and 25% for the bladder, however the knowledge based constraints were more stringent: 8.48 ± 2.65% for the rectum and 4.90 ± 1.98% for the bladder. 19 ± 10 mm single leaf and 1.9 ± 0.7 mm single bank offsets resulted in rectum DVHs worse than 97.7% (2σ) of clinically accepted plans. PTV degradations fell outside of the acceptable range for 0.6 ± 0.3 mm leaf offsets, 0.11 ± 0.06 mm bank offsets, 0.6 ± 1.3 mm of random noise, and 1.0 ± 0.7° of gantry-MLC lag.Utilizing a training set comprised of prior treatment plans, machine learning is used to predict a range of achievable DVHs for the test patient's anatomy. Consequently, degradations leading to statistical outliers may be identified. A knowledge based QA evaluation enables customized QA criteria per treatment site, institution and/or physician and can often be more sensitive to errors than criteria based on organ complication rates.

Authors
Stanhope, C; Wu, QJ; Yuan, L; Liu, J; Hood, R; Yin, F-F; Adamson, J
MLA Citation
Stanhope, C, Wu, QJ, Yuan, L, Liu, J, Hood, R, Yin, F-F, and Adamson, J. "Utilizing knowledge from prior plans in the evaluation of quality assurance." Physics in medicine and biology 60.12 (June 9, 2015): 4873-4891.
PMID
26056801
Source
epmc
Published In
Physics in Medicine and Biology
Volume
60
Issue
12
Publish Date
2015
Start Page
4873
End Page
4891
DOI
10.1088/0031-9155/60/12/4873

Dosimetric Analysis of Microscopic Disease in SBRT for Lung Cancers

Authors
Mao, R; Zhang, Y; Ren, L; Tian, L; Gao, R; Ge, H; Yin, F
MLA Citation
Mao, R, Zhang, Y, Ren, L, Tian, L, Gao, R, Ge, H, and Yin, F. "Dosimetric Analysis of Microscopic Disease in SBRT for Lung Cancers." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3400
End Page
3400

Dosimetric Accuracy of CBCT Images Estimated by a Motion Modeling and Free-Form Deformation Technique for Radiotherapy of Lung Cancer

Authors
Zhang, Y; Yin, F; Ren, L
MLA Citation
Zhang, Y, Yin, F, and Ren, L. "Dosimetric Accuracy of CBCT Images Estimated by a Motion Modeling and Free-Form Deformation Technique for Radiotherapy of Lung Cancer." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3669
End Page
3669

Deformable Registration-Based Image Estimation Method for 4D CBCT Using Region-Based PCA

Authors
Harris, W; Zhang, Y; Yin, F; Ren, L
MLA Citation
Harris, W, Zhang, Y, Yin, F, and Ren, L. "Deformable Registration-Based Image Estimation Method for 4D CBCT Using Region-Based PCA." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3729
End Page
3730

Phantom Research On Monochromatic Images Taken by Dual CBCT with Multiple Energy Sets

Authors
Gao, R; Wang, H; Zhang, Y; Mao, R; Ren, L; Yin, F
MLA Citation
Gao, R, Wang, H, Zhang, Y, Mao, R, Ren, L, and Yin, F. "Phantom Research On Monochromatic Images Taken by Dual CBCT with Multiple Energy Sets." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3250
End Page
3250

A Novel Technique for Markerless Self-Sorted 4D-CBCT Using Patient Motion Modeling: A Feasibility Study

Authors
Zhang, L; Zhang, Y; Harris, W; Yin, F; Ren, L
MLA Citation
Zhang, L, Zhang, Y, Harris, W, Yin, F, and Ren, L. "A Novel Technique for Markerless Self-Sorted 4D-CBCT Using Patient Motion Modeling: A Feasibility Study." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3269
End Page
3269

Volumetric Cine MRI (VC-MRI) Estimated Based On Prior Knowledge for On-Board Target Localization

Authors
Harris, W; Yin, F; Cai, J; Zhang, Y; Ren, L
MLA Citation
Harris, W, Yin, F, Cai, J, Zhang, Y, and Ren, L. "Volumetric Cine MRI (VC-MRI) Estimated Based On Prior Knowledge for On-Board Target Localization." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3689
End Page
3689

A BOLD Contrast Imaging Sequence to Evaluate Oxygenation Changes Due to Breath Holding for Breast Radiotherapy: A Pilot Study

Authors
Adamson, J; Chang, Z; Cai, J; Palta, M; Horton, J; Yin, F; Blitzblau, R
MLA Citation
Adamson, J, Chang, Z, Cai, J, Palta, M, Horton, J, Yin, F, and Blitzblau, R. "A BOLD Contrast Imaging Sequence to Evaluate Oxygenation Changes Due to Breath Holding for Breast Radiotherapy: A Pilot Study." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3317
End Page
3317

Retrospective 4D-MRI with a Novel Image-Based Surrogate: A Sagittal-Coronal-Diaphragm Point of Intersection (SCD-PoI) Motion Tracking Method

Authors
Liu, Y; Yin, F; Czito, B; Bashir, M; Palta, M; Cai, I
MLA Citation
Liu, Y, Yin, F, Czito, B, Bashir, M, Palta, M, and Cai, I. "Retrospective 4D-MRI with a Novel Image-Based Surrogate: A Sagittal-Coronal-Diaphragm Point of Intersection (SCD-PoI) Motion Tracking Method." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3736
End Page
3736

Development of Physiological-Based Virtual Thorax Phantoms for Evaluation of Deformable Image Registration

Authors
Hu, L; Cui, T; Miller, W; Yin, F; Cai, J
MLA Citation
Hu, L, Cui, T, Miller, W, Yin, F, and Cai, J. "Development of Physiological-Based Virtual Thorax Phantoms for Evaluation of Deformable Image Registration." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3655
End Page
3655

Physiological Modeling of Lung Motion Based On Hyperpolarized Gas Tagging MRI

Authors
Cui, T; Hu, L; Miller, W; Yin, F; Cai, J
MLA Citation
Cui, T, Hu, L, Miller, W, Yin, F, and Cai, J. "Physiological Modeling of Lung Motion Based On Hyperpolarized Gas Tagging MRI." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3733
End Page
3734

Displacement Vector Field (DVF) Error Correction Using Sparsely Distributed Ground-Truth Displacement Vectors

Authors
Liang, X; Hu, L; Yin, F; Cai, J
MLA Citation
Liang, X, Hu, L, Yin, F, and Cai, J. "Displacement Vector Field (DVF) Error Correction Using Sparsely Distributed Ground-Truth Displacement Vectors." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3653
End Page
3653

An Investigation of Respiratory Signal Parameters for Multiple-Step Ahead Prediction of Surrogate Motion

Authors
Zawisza, I; Ren, L; Yin, F
MLA Citation
Zawisza, I, Ren, L, and Yin, F. "An Investigation of Respiratory Signal Parameters for Multiple-Step Ahead Prediction of Surrogate Motion." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3711
End Page
3711

Does Online Adaptive Radiation Therapy Mean Zero Margin for Intermediate-Risk Prostate Cancer? An Intra-Fractional Seminal Vesicles Motion Analysis

Authors
Sheng, Y; Li, T; Lee, W; Yin, F; Wu, Q
MLA Citation
Sheng, Y, Li, T, Lee, W, Yin, F, and Wu, Q. "Does Online Adaptive Radiation Therapy Mean Zero Margin for Intermediate-Risk Prostate Cancer? An Intra-Fractional Seminal Vesicles Motion Analysis." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3591
End Page
3591

Rapid Projection Computations for On-Board Digital Tomosynthesis in Radiation Therapy

Authors
Iliopoulos, AS; Pitsianis, N; Sun, X; Yin, FF; Ren, L
MLA Citation
Iliopoulos, AS, Pitsianis, N, Sun, X, Yin, FF, and Ren, L. "Rapid Projection Computations for On-Board Digital Tomosynthesis in Radiation Therapy." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3658
End Page
3658

Therapeutic Response Assessment Using a Novel Gray Level Local Power Matrix (GLLPM) in DCE-MRI Texture Analysis: Feasibility Study

Authors
Wang, C; Subashi, E; Yin, F; Chang, Z
MLA Citation
Wang, C, Subashi, E, Yin, F, and Chang, Z. "Therapeutic Response Assessment Using a Novel Gray Level Local Power Matrix (GLLPM) in DCE-MRI Texture Analysis: Feasibility Study." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3212
End Page
3213

Probability-Driven Sorting Method for Reconstructing Variation-Independent 4D-MRI

Authors
Liang, X; Liu, Y; Yin, F; Cai, J
MLA Citation
Liang, X, Liu, Y, Yin, F, and Cai, J. "Probability-Driven Sorting Method for Reconstructing Variation-Independent 4D-MRI." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3734
End Page
3734

Sensitivity Analysis to Machine Error: Comparisons of VMAT QA Systems

Authors
Liang, B; Liu, B; Yin, F; Zhou, F; Wu, Q
MLA Citation
Liang, B, Liu, B, Yin, F, Zhou, F, and Wu, Q. "Sensitivity Analysis to Machine Error: Comparisons of VMAT QA Systems." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3495
End Page
3495

Development of Knowledge Models for IMRT Treatment Planning Utilizing a Rapid Learning Approach

Authors
Yuan, L; Ge, Y; Sheng, Y; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Sheng, Y, Yin, F, and Wu, QJ. "Development of Knowledge Models for IMRT Treatment Planning Utilizing a Rapid Learning Approach." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3580
End Page
3580

Sliding Motion Compensated Simultaneous 4D-CBCT Reconstruction

Authors
Dang, J; Yin, F; You, T; Dai, C; Wang, J
MLA Citation
Dang, J, Yin, F, You, T, Dai, C, and Wang, J. "Sliding Motion Compensated Simultaneous 4D-CBCT Reconstruction." June 2015.
Source
wos-lite
Published In
Medical physics
Volume
42
Issue
6
Publish Date
2015
Start Page
3731
End Page
3731

Flattening filter-free accelerators: a report from the AAPM Therapy Emerging Technology Assessment Work Group.

This report describes the current state of flattening filter-free (FFF) radiotherapy beams implemented on conventional linear accelerators, and is aimed primarily at practicing medical physicists. The Therapy Emerging Technology Assessment Work Group of the American Association of Physicists in Medicine (AAPM) formed a writing group to assess FFF technology. The published literature on FFF technology was reviewed, along with technical specifications provided by vendors. Based on this information, supplemented by the clinical experience of the group members, consensus guidelines and recommendations for implementation of FFF technology were developed. Areas in need of further investigation were identified. Removing the flattening filter increases beam intensity, especially near the central axis. Increased intensity reduces treatment time, especially for high-dose stereotactic radiotherapy/radiosurgery (SRT/SRS). Furthermore, removing the flattening filter reduces out-of-field dose and improves beam modeling accuracy. FFF beams are advantageous for small field (e.g., SRS) treatments and are appropriate for intensity-modulated radiotherapy (IMRT). For conventional 3D radiotherapy of large targets, FFF beams may be disadvantageous compared to flattened beams because of the heterogeneity of FFF beam across the target (unless modulation is employed). For any application, the nonflat beam characteristics and substantially higher dose rates require consideration during the commissioning and quality assurance processes relative to flattened beams, and the appropriate clinical use of the technology needs to be identified. Consideration also needs to be given to these unique characteristics when undertaking facility planning. Several areas still warrant further research and development. Recommendations pertinent to FFF technology, including acceptance testing, commissioning, quality assurance, radiation safety, and facility planning, are presented. Examples of clinical applications are provided. Several of the areas in which future research and development are needed are also indicated.

Authors
Xiao, Y; Kry, SF; Popple, R; Yorke, E; Papanikolaou, N; Stathakis, S; Xia, P; Huq, S; Bayouth, J; Galvin, J; Yin, F-F
MLA Citation
Xiao, Y, Kry, SF, Popple, R, Yorke, E, Papanikolaou, N, Stathakis, S, Xia, P, Huq, S, Bayouth, J, Galvin, J, and Yin, F-F. "Flattening filter-free accelerators: a report from the AAPM Therapy Emerging Technology Assessment Work Group." Journal of applied clinical medical physics 16.3 (May 8, 2015): 5219-.
PMID
26103482
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
16
Issue
3
Publish Date
2015
Start Page
5219
DOI
10.1120/jacmp.v16i3.5219

A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs.

To develop a framework for accurate electron Monte Carlo dose calculation. In this study, comprehensive validations of vendor provided electron beam phase space files for Varian TrueBeam Linacs against measurement data are presented.In this framework, the Monte Carlo generated phase space files were provided by the vendor and used as input to the downstream plan-specific simulations including jaws, electron applicators, and water phantom computed in the EGSnrc environment. The phase space files were generated based on open field commissioning data. A subset of electron energies of 6, 9, 12, 16, and 20 MeV and open and collimated field sizes 3 × 3, 4 × 4, 5 × 5, 6 × 6, 10 × 10, 15 × 15, 20 × 20, and 25 × 25 cm(2) were evaluated. Measurements acquired with a CC13 cylindrical ionization chamber and electron diode detector and simulations from this framework were compared for a water phantom geometry. The evaluation metrics include percent depth dose, orthogonal and diagonal profiles at depths R100, R50, Rp, and Rp+ for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors.Agreement for the percent depth dose and orthogonal profiles between measurement and Monte Carlo was generally within 2% or 1 mm. The largest discrepancies were observed within depths of 5 mm from phantom surface. Differences in field size, penumbra, and flatness for the orthogonal profiles at depths R100, R50, and Rp were within 1 mm, 1 mm, and 2%, respectively. Orthogonal profiles at SSDs of 100 and 120 cm showed the same level of agreement. Cone and cut-out output factors agreed well with maximum differences within 2.5% for 6 MeV and 1% for all other energies. Cone output factors at extended SSDs of 105, 110, 115, and 120 cm exhibited similar levels of agreement.We have presented a Monte Carlo simulation framework for electron beam dose calculations for Varian TrueBeam Linacs. Electron beam energies of 6 to 20 MeV for open and collimated field sizes from 3 × 3 to 25 × 25 cm(2) were studied and results were compared to the measurement data with excellent agreement. Application of this framework can thus be used as the platform for treatment planning of dynamic electron arc radiotherapy and other advanced dynamic techniques with electron beams.

Authors
Rodrigues, A; Sawkey, D; Yin, F-F; Wu, Q
MLA Citation
Rodrigues, A, Sawkey, D, Yin, F-F, and Wu, Q. "A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs." Medical physics 42.5 (May 2015): 2389-2403.
PMID
25979034
Source
epmc
Published In
Medical physics
Volume
42
Issue
5
Publish Date
2015
Start Page
2389
End Page
2403
DOI
10.1118/1.4916896

Preliminary clinical evaluation of a 4D-CBCT estimation technique using prior information and limited-angle projections

© 2015 Elsevier Ireland Ltd. All rights reserved. Background and purpose A technique has been previously reported to estimate high-quality 4D-CBCT using prior information and limited-angle projections. This study is to investigate its clinical feasibility through both phantom and patient studies. Materials and methods The new technique used to estimate 4D-CBCT is called MMFD-NCC. It is based on the previously reported motion modeling and free-form deformation (MMFD) method, with the introduction of normalized-cross-correlation (NCC) as a new similarity metric. The clinical feasibility of this technique was evaluated by assessing the accuracy of estimated anatomical structures in comparison to those in the 'ground-truth' reference 4D-CBCTs, using data obtained from a physical phantom and three lung cancer patients. Both volume percentage error (VPE) and center-of-mass error (COME) of the estimated tumor volume were used as the evaluation metrics. Results The average VPE/COME of the tumor in the prior image was 257.1%/10.1 mm for the phantom study and 55.6%/3.8 mm for the patient study. Using only orthogonal-view 30° projections, the MMFD-NCC has reduced the corresponding values to 7.7%/1.2 mm and 9.6%/1.1 mm, respectively. Conclusion The MMFD-NCC technique is able to estimate 4D-CBCT images with geometrical accuracy of the tumor within 10% VPE and 2 mm COME, which can be used to improve the localization accuracy of radiotherapy.

Authors
Zhang, Y; Yin, FF; Pan, T; Vergalasova, I; Ren, L
MLA Citation
Zhang, Y, Yin, FF, Pan, T, Vergalasova, I, and Ren, L. "Preliminary clinical evaluation of a 4D-CBCT estimation technique using prior information and limited-angle projections." Radiotherapy and Oncology 115.1 (April 1, 2015): 22-29.
Source
scopus
Published In
Radiotherapy & Oncology
Volume
115
Issue
1
Publish Date
2015
Start Page
22
End Page
29
DOI
10.1016/j.radonc.2015.02.022

Preliminary clinical evaluation of a 4D-CBCT estimation technique using prior information and limited-angle projections.

A technique has been previously reported to estimate high-quality 4D-CBCT using prior information and limited-angle projections. This study is to investigate its clinical feasibility through both phantom and patient studies.The new technique used to estimate 4D-CBCT is called MMFD-NCC. It is based on the previously reported motion modeling and free-form deformation (MMFD) method, with the introduction of normalized-cross-correlation (NCC) as a new similarity metric. The clinical feasibility of this technique was evaluated by assessing the accuracy of estimated anatomical structures in comparison to those in the 'ground-truth' reference 4D-CBCTs, using data obtained from a physical phantom and three lung cancer patients. Both volume percentage error (VPE) and center-of-mass error (COME) of the estimated tumor volume were used as the evaluation metrics.The average VPE/COME of the tumor in the prior image was 257.1%/10.1 mm for the phantom study and 55.6%/3.8 mm for the patient study. Using only orthogonal-view 30° projections, the MMFD-NCC has reduced the corresponding values to 7.7%/1.2 mm and 9.6%/1.1 mm, respectively.The MMFD-NCC technique is able to estimate 4D-CBCT images with geometrical accuracy of the tumor within 10% VPE and 2 mm COME, which can be used to improve the localization accuracy of radiotherapy.

Authors
Zhang, Y; Yin, F-F; Pan, T; Vergalasova, I; Ren, L
MLA Citation
Zhang, Y, Yin, F-F, Pan, T, Vergalasova, I, and Ren, L. "Preliminary clinical evaluation of a 4D-CBCT estimation technique using prior information and limited-angle projections." Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 115.1 (April 2015): 22-29.
PMID
25818396
Source
epmc
Published In
Radiotherapy & Oncology
Volume
115
Issue
1
Publish Date
2015
Start Page
22
End Page
29
DOI
10.1016/j.radonc.2015.02.022

Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: the benefits of DVH prediction.

A recent publication indicated that the patient anatomical feature (PAF) model was capable of predicting optimal objectives based on past experience. In this study, the benefits of IMRT optimization using PAF-predicted objectives as guidance for prostate were evaluated. Three different optimization methods were compared.1) Expert Plan: Ten prostate cases (16 plans) were planned by an expert planner using conventional trial-and-error approach started with institutional modified OAR and PTV constraints. Optimization was stopped at 150 iterations and that plan was saved as Expert Plan. 2) Clinical Plan: The planner would keep working on the Expert Plan till he was satisfied with the dosimetric quality and the final plan was referred to as Clinical Plan. 3) PAF Plan: A third sets of plans for the same ten patients were generated fully automatically using predicted DVHs as guidance. The optimization was based on PAF-based predicted objectives, and was continued to 150 iterations without human interaction. DMAX and D98% for PTV, DMAX for femoral heads, DMAX, D10cc, D25%/D17%, and D40% for bladder/rectum were compared. Clinical Plans are further optimized with more iterations and adjustments, but in general provided limited dosimetric benefits over Expert Plans. PTV D98% agreed within 2.31% among Expert, Clinical, and PAF plans. Between Clinical and PAF Plans, differences for DMAX of PTV, bladder, and rectum were within 2.65%, 2.46%, and 2.20%, respectively. Bladder D10cc was higher for PAF but < 1.54% in general. Bladder D25% and D40% were lower for PAF, by up to 7.71% and 6.81%, respectively. Rectum D10cc, D17%, and D40% were 2.11%, 2.72%, and 0.27% lower for PAF, respectively. DMAX for femoral heads were comparable (< 35 Gy on average). Compared to Clinical Plan (Primary + Boost), the average optimization time for PAF plan was reduced by 5.2 min on average, with a maximum reduction of 7.1min. Total numbers of MUs per plan for PAF Plans were lower than Clinical Plans, indicating better delivery efficiency. The PAF-guided planning process is capable of generating clinical-quality prostate IMRT plans with no human intervention. Compared to manual optimization, this automatic optimization increases planning and delivery efficiency, while maintainingplan quality.

Authors
Yang, Y; Li, T; Yuan, L; Ge, Y; Yin, F-F; Lee, WR; Wu, QJ
MLA Citation
Yang, Y, Li, T, Yuan, L, Ge, Y, Yin, F-F, Lee, WR, and Wu, QJ. "Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: the benefits of DVH prediction." Journal of applied clinical medical physics 16.2 (March 8, 2015): 5204-.
PMID
26103191
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
16
Issue
2
Publish Date
2015
Start Page
5204
DOI
10.1120/jacmp.v16i2.5204

Standardized beam bouquets for lung IMRT planning.

The selection of the incident angles of the treatment beams is a critical component of intensity modulated radiation therapy (IMRT) planning for lung cancer due to significant variations in tumor location, tumor size and patient anatomy. We investigate the feasibility of establishing a small set of standardized beam bouquets for planning. The set of beam bouquets were determined by learning the beam configuration features from 60 clinical lung IMRT plans designed by experienced planners. A k-medoids cluster analysis method was used to classify the beam configurations in the dataset. The appropriate number of clusters was determined by maximizing the value of average silhouette width of the classification. Once the number of clusters had been determined, the beam arrangements in each medoid of the clusters were designated as the standardized beam bouquet for the cluster. This standardized bouquet set was used to re-plan 20 cases randomly selected from the clinical database. The dosimetric quality of the plans using the beam bouquets was evaluated against the corresponding clinical plans by a paired t-test. The classification with six clusters has the largest average silhouette width value and hence would best represent the beam bouquet patterns in the dataset. The results shows that plans generated with a small number of standardized bouquets (e.g. 6) have comparable quality to that of clinical plans. These standardized beam configuration bouquets will potentially help improve plan efficiency and facilitate automated planning.

Authors
Yuan, L; Wu, QJ; Yin, F; Li, Y; Sheng, Y; Kelsey, CR; Ge, Y
MLA Citation
Yuan, L, Wu, QJ, Yin, F, Li, Y, Sheng, Y, Kelsey, CR, and Ge, Y. "Standardized beam bouquets for lung IMRT planning." Physics in medicine and biology 60.5 (March 2015): 1831-1843.
PMID
25658486
Source
epmc
Published In
Physics in Medicine and Biology
Volume
60
Issue
5
Publish Date
2015
Start Page
1831
End Page
1843
DOI
10.1088/0031-9155/60/5/1831

From active shape model to active optical flow model: a shape-based approach to predicting voxel-level dose distributions in spine SBRT.

Prediction of achievable dose distribution in spine stereotactic body radiation therapy (SBRT) can help in designing high-quality treatment plans to maximally protect spinal cords and to effectively control tumours. Dose distributions at spinal cords are primarily affected by the shapes of adjacent planning target volume (PTV) contours. In this work, we estimate such contour effects and predict dose distributions by exploring active optical flow model (AOFM) and active shape model (ASM). We first collect a sequence of dose sub-images and PTV contours near spinal cords from fifteen SBRT plans in the training dataset. The data collection is then classified into five groups according to the PTV locations in relation to spinal cords. In each group, we randomly choose a dose sub-image as the reference and register all other sub-images to the reference using an optical flow method. AOFM is then constructed by importing optical flow vectors and dose values into the principal component analysis (PCA). Similarly, we build ASM by using PCA on PTV contour points. The correlation between ASM and AOFM is estimated via a stepwise multiple regression model. When predicting dose distribution of a new case, the group is first determined based on the PTV contour. The prediction model of the selected group is used to estimate dose distributions by mapping the PTV contours from the ASM space to the AOFM space. This method was validated on fifteen SBRT plans in the testing dataset. Analysis of dose-volume histograms revealed that the important D2%, D5%, D10% and D0.1cc dosimetric parameters of spinal cords between the prediction and the clinical plans were 11.7 ± 1.7 Gy versus 11.8 ± 1.7 Gy (p = 0.95), 10.9 ± 1.7 Gy versus 11.1 ± 1.9 Gy (p = 0.8295), 10.2 ± 1.6 Gy versus 10.1 ± 1.7 (p = 0.9036) and 11.2 ± 2.0 Gy versus 11.1 ± 2.2 Gy (p = 0.5208), respectively. Here, the ‘cord’ is the spinal cord proper (not the thecal sac) extended 5 mm inferior and superior to the involved vertebral bodies, and the ‘PTV’ is the involved segment of the vertebral body expanded uniformly by 2 mm but excluding the spinal cord volume expanded by 2 mm (Ref. RTOG 0631). These results suggested that the AOFM-based approach is a promising tool for predicting accurate spinal cord dose in clinical practice. In this work, we demonstrated the feasibility of using AOFM and ASM models derived from previously treated patients to estimate the achievable dose distributions for new patients.

Authors
Liu, J; Wu, QJ; Kirkpatrick, JP; Yin, F-F; Yuan, L; Ge, Y
MLA Citation
Liu, J, Wu, QJ, Kirkpatrick, JP, Yin, F-F, Yuan, L, and Ge, Y. "From active shape model to active optical flow model: a shape-based approach to predicting voxel-level dose distributions in spine SBRT." Physics in medicine and biology 60.5 (March 2015): N83-N92.
PMID
25675394
Source
epmc
Published In
Physics in Medicine and Biology
Volume
60
Issue
5
Publish Date
2015
Start Page
N83
End Page
N92
DOI
10.1088/0031-9155/60/5/n83

Four dimensional magnetic resonance imaging with retrospective k-space reordering: a feasibility study.

Current four dimensional magnetic resonance imaging (4D-MRI) techniques lack sufficient temporal/spatial resolution and consistent tumor contrast. To overcome these limitations, this study presents the development and initial evaluation of a new strategy for 4D-MRI which is based on retrospective k-space reordering.We simulated a k-space reordered 4D-MRI on a 4D digital extended cardiac-torso (XCAT) human phantom. A 2D echo planar imaging MRI sequence [frame rate (F) = 0.448 Hz; image resolution (R) = 256 × 256; number of k-space segments (NKS) = 4] with sequential image acquisition mode was assumed for the simulation. Image quality of the simulated "4D-MRI" acquired from the XCAT phantom was qualitatively evaluated, and tumor motion trajectories were compared to input signals. In particular, mean absolute amplitude differences (D) and cross correlation coefficients (CC) were calculated. Furthermore, to evaluate the data sufficient condition for the new 4D-MRI technique, a comprehensive simulation study was performed using 30 cancer patients' respiratory profiles to study the relationships between data completeness (Cp) and a number of impacting factors: the number of repeated scans (NR), number of slices (NS), number of respiratory phase bins (NP), NKS, F, R, and initial respiratory phase at image acquisition (P0). As a proof-of-concept, we implemented the proposed k-space reordering 4D-MRI technique on a T2-weighted fast spin echo MR sequence and tested it on a healthy volunteer.The simulated 4D-MRI acquired from the XCAT phantom matched closely to the original XCAT images. Tumor motion trajectories measured from the simulated 4D-MRI matched well with input signals (D = 0.83 and 0.83 mm, and CC = 0.998 and 0.992 in superior-inferior and anterior-posterior directions, respectively). The relationship between Cp and NR was found best represented by an exponential function (CP=1001-e(-0.18NR) , when NS = 30, NP = 6). At a CP value of 95%, the relative error in tumor volume was 0.66%, indicating that NR at a CP value of 95% (NR,95%) is sufficient. It was found that NR,95% is approximately linearly proportional to NP (r = 0.99), and nearly independent of all other factors. The 4D-MRI images of the healthy volunteer clearly demonstrated respiratory motion in the diaphragm region with minimal motion induced noise or aliasing.It is feasible to generate respiratory correlated 4D-MRI by retrospectively reordering k-space based on respiratory phase. This new technology may lead to the next generation 4D-MRI with high spatiotemporal resolution and optimal tumor contrast, holding great promises to improve the motion management in radiotherapy of mobile cancers.

Authors
Liu, Y; Yin, F-F; Chen, N-K; Chu, M-L; Cai, J
MLA Citation
Liu, Y, Yin, F-F, Chen, N-K, Chu, M-L, and Cai, J. "Four dimensional magnetic resonance imaging with retrospective k-space reordering: a feasibility study." Medical physics 42.2 (February 2015): 534-541.
PMID
25652474
Source
epmc
Published In
Medical physics
Volume
42
Issue
2
Publish Date
2015
Start Page
534
End Page
541
DOI
10.1118/1.4905044

Dosimetric comparison of preoperative single-fraction partial breast radiotherapy techniques: 3D CRT, noncoplanar IMRT, coplanar IMRT, and VMAT.

The purpose of this study was to compare dosimetric parameters of treatment plans among four techniques for preoperative single-fraction partial breast radiotherapy in order to select an optimal treatment technique. The techniques evaluated were noncoplanar 3D conformal radiation therapy (3D CRT), noncoplanar intensity-modulated radiation therapy (IMRTNC), coplanar IMRT (IMRTCO), and volumetric-modulated arc therapy (VMAT). The planning CT scans of 16 patients in the prone position were used in this study, with the single-fraction prescription doses of 15 Gy for the first eight patients and 18 Gy for the remaining eight patients. Six (6) MV photon beams were designed to avoid the heart and contralateral breast. Optimization for IMRT and VMAT was performed to reduce the dose to the skin and normal breast. All plans were normalized such that 100% of the prescribed dose covered greater than 95% of the clinical target volume (CTV) consisting of gross tumor volume (GTV) plus 1.5 cm margin. Mean homogeneity index (HI) was the lowest (1.05 ± 0.02) for 3D CRT and the highest (1.11 ± 0.04) for VMAT. Mean conformity index (CI) was the lowest (1.42 ± 0.32) for IMRTNC and the highest (1.60 ± 0.32) for VMAT. Mean of the maximum point dose to skin was the lowest (73.7 ± 11.5%) for IMRTNC and the highest (86.5 ± 6.68%) for 3D CRT. IMRTCO showed very similar HI, CI, and maximum skin dose to IMRTNC (differences <1%). The estimated mean treatment delivery time, excluding the time spent for patient positioning and imaging, was 7.0 ± 1.0, 8.3 ± 1.1, 9.7 ± 1.0, and 11.0 ± 1.5min for VMAT, IMRTCO, IMRTNC and 3D CRT, respectively. In comparison of all four techniques for preoperative single-fraction partial breast radiotherapy, we can conclude that noncoplanar or coplanar IMRT were optimal in this study as IMRT plans provided homogeneous and conformal target coverage, skin sparing, and relatively short treatment delivery time.

Authors
Yoo, S; Blitzblau, R; Yin, F-F; Horton, JK
MLA Citation
Yoo, S, Blitzblau, R, Yin, F-F, and Horton, JK. "Dosimetric comparison of preoperative single-fraction partial breast radiotherapy techniques: 3D CRT, noncoplanar IMRT, coplanar IMRT, and VMAT." Journal of applied clinical medical physics 16.1 (January 8, 2015): 5126-.
PMID
25679170
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
16
Issue
1
Publish Date
2015
Start Page
5126
DOI
10.1120/jacmp.v16i1.5126

Impact of dose calculation accuracy during optimization on lung IMRT plan quality.

The purpose of this study was to evaluate the effect of dose calculation accuracy and the use of an intermediate dose calculation step during the optimization of intensity-modulated radiation therapy (IMRT) planning on the final plan quality for lung cancer patients. This study included replanning for 11 randomly selected free-breathing lung IMRT plans. The original plans were optimized using a fast pencil beam convolution algorithm. After optimization, the final dose calculation was performed using the analytical anisotropic algorithm (AAA). The Varian Treatment Planning System (TPS) Eclipse v11, includes an option to perform intermediate dose calculation during optimization using the AAA. The new plans were created using this intermediate dose calculation during optimization with the same planning objectives and dose constraints as in the original plan. Differences in dosimetric parameters for the planning target volume (PTV) dose coverage, organs-at-risk (OARs) dose sparing, and the number of monitor units (MU) between the original and new plans were analyzed. Statistical significance was determined with a p-value of less than 0.05. All plans were normalized to cover 95% of the PTV with the prescription dose. Compared with the original plans, the PTV in the new plans had on average a lower maximum dose (69.45 vs. 71.96Gy, p = 0.005), a better homogeneity index (HI) (0.08 vs. 0.12, p = 0.002), and a better conformity index (CI) (0.69 vs. 0.59, p = 0.003). In the new plans, lung sparing was increased as the volumes receiving 5, 10, and 30 Gy were reduced when compared to the original plans (40.39% vs. 42.73%, p = 0.005; 28.93% vs. 30.40%, p = 0.001; 14.11%vs. 14.84%, p = 0.031). The volume receiving 20 Gy was not significantly lower (19.60% vs. 20.38%, p = 0.052). Further, the mean dose to the lung was reduced in the new plans (11.55 vs. 12.12 Gy, p = 0.024). For the esophagus, the mean dose, the maximum dose, and the volumes receiving 20 and 60 Gy were lower in the new plans than in the original plans (17.91 vs. 19.24 Gy, p = 0.004; 57.32vs. 59.81 Gy, p = 0.020; 39.34% vs. 41.59%, p = 0.097; 12.56%vs. 15.35%, p = 0.101). For the heart, the mean dose, the maximum dose, and the volume receiving 40 Gy were also lower in new plans (11.07 vs. 12.04 Gy, p = 0.007; 56.41 vs. 57.7 Gy, p = 0.027; 7.16% vs. 9.37%, p= 0.012). The maximum dose to the spinal cord in the new plans was significantly lower than in the original IMRT plans (29.1 vs. 31.39Gy, p = 0.014). Difference in MU between the IMRT plans was not significant (1216.90 vs. 1198.91, p = 0.328). In comparison to the original plans, the number of iterations needed to meet the optimization objectives in the new plans was reduced by a factor of 2 (2-3 vs. 5-6 iterations). Further, optimization was 30% faster corresponding to an average time savings of 10-15 min for the reoptimized plans. Accuracy of the dose calculation algorithm during optimization has an impact on planning efficiency, as well as on the final plan dosimetric quality. For lung IMRT treatment planning, utilizing the intermediate dose calculation during optimization is feasible for dose homogeneity improvement of the PTV and for improvement of optimization efficiency.

Authors
Li, Y; Rodrigues, A; Li, T; Yuan, L; Yin, F-F; Wu, QJ
MLA Citation
Li, Y, Rodrigues, A, Li, T, Yuan, L, Yin, F-F, and Wu, QJ. "Impact of dose calculation accuracy during optimization on lung IMRT plan quality." Journal of applied clinical medical physics 16.1 (January 8, 2015): 5137-.
PMID
25679172
Source
epmc
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
16
Issue
1
Publish Date
2015
Start Page
5137
DOI
10.1120/jacmp.v16i1.5137

Dosimetric comparison of preoperative single-fraction partial breast radiotherapy techniques: 3D CRT, noncoplanar IMRT, coplanar IMRT, and VMAT

The purpose of this study was to compare dosimetric parameters of treatment plans among four techniques for preoperative single-fraction partial breast radiotherapy in order to select an optimal treatment technique. The techniques evaluated were noncoplanar 3D conformal radiation therapy (3D CRT), noncoplanar intensity-modulated radiation therapy (IMRT NC ), coplanar IMRT (IMRT CO ), and volumetric-modulated arc therapy (VMAT). The planning CT scans of 16 patients in the prone position were used in this study, with the single-fraction prescription doses of 15 Gy for the first eight patients and 18 Gy for the remaining eight patients. Six (6) MV photon beams were designed to avoid the heart and contralateral breast. Optimization for IMRT and VMAT was performed to reduce the dose to the skin and normal breast. All plans were normalized such that 100% of the prescribed dose covered greater than 95% of the clinical target volume (CTV) consisting of gross tumor volume (GTV) plus 1.5 cm margin. Mean homogeneity index (HI) was the lowest (1.05 ± 0.02) for 3D CRT and the highest (1.11 ± 0.04) for VMAT. Mean conformity index (CI) was the lowest (1.42 ± 0.32) for IMRT NC and the highest (1.60 ± 0.32) for VMAT. Mean of the maximum point dose to skin was the lowest (73.7 ± 11.5%) for IMRT NC and the highest (86.5 ± 6.68%) for 3D CRT. IMRT CO showed very similar HI, CI, and maximum skin dose to IMRT NC (differences < 1%). The estimated mean treatment delivery time, excluding the time spent for patient positioning and imaging, was 7.0 ± 1.0, 8.3 ± 1.1, 9.7 ± 1.0, and 11.0 ± 1.5min for VMAT, IMRT CO , IMRT NC and 3D CRT, respectively. In comparison of all four techniques for preoperative single-fraction partial breast radiotherapy, we can conclude that noncoplanar or coplanar IMRT were optimal in this study as IMRT plans provided homogeneous and conformal target coverage, skin sparing, and relatively short treatment delivery time.

Authors
Yoo, S; Blitzblau, R; Yin, FF; Horton, JK
MLA Citation
Yoo, S, Blitzblau, R, Yin, FF, and Horton, JK. "Dosimetric comparison of preoperative single-fraction partial breast radiotherapy techniques: 3D CRT, noncoplanar IMRT, coplanar IMRT, and VMAT." Journal of Applied Clinical Medical Physics 16.1 (January 1, 2015): 183-191.
Source
scopus
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
16
Issue
1
Publish Date
2015
Start Page
183
End Page
191

An active optical flow model for dose prediction in spinal SBRT plans

© Springer International Publishing Switzerland 2015. Accurate dose predication is critical to spinal stereotactic body radiation therapy (SBRT). It enables radiation oncologists and planners to design treatment plans that maximally protect spinal cord while effectively controlling surrounding tumors. Spinal cord dose distribution is primarily affected by the shapes of tumor boundaries near the organ. In this work, we estimate such boundary effects and predict dose distribution by exploring an active optical flow model (AOFM). To establish AOFM, we collect a sequence of dose sub-images and tumor contours near spinal cords from a database of clinically accepted spine SBRT plans. The data are classified into five groups according to the tumor location in relation to the spinal cords. In each group, we randomly choose a dose sub-image as the reference and register all other dose images to the reference using an optical flow method. AOFM is then constructed by importing optical flow vectors and dose values into the principal component analysis. To develop the predictive model for a group, we also build active shape model (ASM) of tumor contours near the spinal cords. The correlation between ASM and AOFM is estimated via the multiple regression model. When predicting dose distribution of a new case, the group was first determined based on the case's tumor contour. Then the corresponding model for the group is used to map from the ASM space to the AOFM space. Finally, the parameters in the AOFM space are used to estimate dose distribution. This method was validated on 30 SBRT plans. Analysis of dose-volume histograms revealed that at the important 2 % volume mark, the dose difference between prediction and clinical plan is less than 4 %. These results suggest that the AOFM-based approach is a promising tool for predicting accurate spinal cord dose in clinical practice.

Authors
Liu, J; Wu, QJ; Yin, FF; Kirkpatrick, JP; Cabrera, A; Ge, Y
MLA Citation
Liu, J, Wu, QJ, Yin, FF, Kirkpatrick, JP, Cabrera, A, and Ge, Y. "An active optical flow model for dose prediction in spinal SBRT plans." January 1, 2015.
Source
scopus
Published In
Lecture Notes in Engineering and Computer Science
Volume
20
Publish Date
2015
Start Page
27
End Page
35
DOI
10.1007/978-3-319-14148-0-3

An active optical flow model for dose prediction in spinal sbrt plans

© Springer International Publishing Switzerland 2015. Accurate dose predication is critical to spinal stereotactic body radiation therapy (SBRT). It enables radiation oncologists and planners to design treatment plans that maximally protect spinal cord while effectively controlling surrounding tumors. Spinal cord dose distribution is primarily affected by the shapes of tumor boundaries near the organ. In this work, we estimate such boundary effects and predict dose distribution by exploring an active optical flow model (AOFM). To establish AOFM, we collect a sequence of dose sub-images and tumor contours near spinal cords from a database of clinically accepted spine SBRT plans. The data are classified into five groups according to the tumor location in relation to the spinal cords. In each group, we randomly choose a dose sub-image as the reference and register all other dose images to the reference using an optical flowmethod. AOFM is then constructed by importing optical flow vectors and dose values into the principal component analysis. To develop the predictivemodel for a group, we also build active shape model (ASM) of tumor contours near the spinal cords. The correlation between ASM and AOFM is estimated via the multiple regression model. When predicting dose distribution of a new case, the group was first determined based on the case’stumor contour. Then the corresponding model for the group is used to map from the ASM space to the AOFM space. Finally, the parameters in the AOFM space are used to estimate dose distribution. This method was validated on 30 SBRT plans. Analysis of dose-volume histograms revealed that at the important 2%volume mark, the dose difference between prediction and clinical plan is less than 4%. These results suggest that theAOFM-based approach is a promising tool for predicting accurate spinal cord dose in clinical practice.

Authors
Liu, J; Jackie Wu, Q; Yin, FF; Kirkpatrick, JP; Cabrera, A; Ge, Y
MLA Citation
Liu, J, Jackie Wu, Q, Yin, FF, Kirkpatrick, JP, Cabrera, A, and Ge, Y. "An active optical flow model for dose prediction in spinal sbrt plans." Lecture Notes in Computational Vision and Biomechanics 20 (January 1, 2015): 27-35.
Source
scopus
Published In
Lecture Notes in Computational Vision and Biomechanics
Volume
20
Publish Date
2015
Start Page
27
End Page
35
DOI
10.1007/978-3-319-14148-0_3

Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: The benefits of DVH predictionQuantitative comparison of automatic and manual IMRT optimization for prostate cancer: The benefits of DVH prediction

A recent publication indicated that the patient anatomical feature (PAF) model was capable of predicting optimal objectives based on past experience. In this study, the benefits of IMRT optimization using PAF-predicted objectives as guidance for prostate were evaluated. Three different optimization methods were compared. 1) Expert Plan: Ten prostate cases (16 plans) were planned by an expert planner using conventional trial-and-error approach started with institutional modified OAR and PTV constraints. Optimization was stopped at 150 iterations and that plan was saved as Expert Plan. 2) Clinical Plan: The planner would keep working on the Expert Plan till he was satisfied with the dosimetric quality and the final plan was referred to as Clinical Plan. 3) PAF Plan: A third sets of plans for the same ten patients were generated fully automatically using predicted DVHs as guidance. The optimization was based on PAF-based predicted objectives, and was continued to 150 iterations without human interaction. D MAX and D 98% for PTV, D MAX for femoral heads, D MAX , D 10cc , D 25% /D 17% , and D 40% for bladder/rectum were compared. Clinical Plans are further optimized with more iterations and adjustments, but in general provided limited dosimetric benefits over Expert Plans. PTV D 98% agreed within 2.31% among Expert, Clinical, and PAF plans. Between Clinical and PAF Plans, differences for D MAX of PTV, bladder, and rectum were within 2.65%, 2.46%, and 2.20%, respectively. Bladder D 10cc was higher for PAF but < 1.54% in general. Bladder D 25% and D 40% were lower for PAF, by up to 7.71% and 6.81%, respectively. Rectum D 10cc , D 17% , and D 40% were 2.11%, 2.72%, and 0.27% lower for PAF, respectively. D MAX for femoral heads were comparable ( < 35 Gy on average). Compared to Clinical Plan (Primary + Boost), the average optimization time for PAF plan was reduced by 5.2 min on average, with a maximum reduction of 7.1min. Total numbers of MUs per plan for PAF Plans were lower than Clinical Plans, indicating better delivery efficiency. The PAF-guided planning process is capable of generating clinical-quality prostate IMRT plans with no human intervention. Compared to manual optimization, this automatic optimization increases planning and delivery efficiency, while maintaining plan quality.

Authors
Yang, Y; Li, T; Yuan, L; Ge, Y; Yin, FF; Lee, WR; Wu, QJ; Yang, Y; Li, T; Yuan, L; Ge, Y; Yin, FF; Lee, WR; Wu, QJ
MLA Citation
Yang, Y, Li, T, Yuan, L, Ge, Y, Yin, FF, Lee, WR, Wu, QJ, Yang, Y, Li, T, Yuan, L, Ge, Y, Yin, FF, Lee, WR, and Wu, QJ. "Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: The benefits of DVH predictionQuantitative comparison of automatic and manual IMRT optimization for prostate cancer: The benefits of DVH prediction (PublishedPublished)." Journal of Applied Clinical Medical Physics 16.2 (January 1, 2015): 241-250.
Source
scopus
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
16
Issue
2
Publish Date
2015
Start Page
241
End Page
250
DOI
10.1120/jacmp.v16i2.5204

Knowledge modeling for computer aided treatment planning

© Springer International Publishing Switzerland 2015. The purpose for this study is to develop robust and comprehensive knowledge models which can provide patient specific prediction of achievable dose distribution in radiation therapy plans for a wide range of cancer types. These models are useful tools to guide radiation therapy planning. Clinical RT plans for a number of cancer types including prostate, head and neck, anorectal, lung and spinal SBRT plans are studied retrospectively. The knowledge modeling correlates patient anatomical features with the dose features embedded in the RT plans. A number of patient’s anatomical and dosimetric features are considered in the model. The geometrical relationships between the OARs and PTV are represented by the distance-to-target histogram, DTH and the distance- to-OAR histogram. Important anatomical and dosimetric features were extracted from DTH and DVH by principal component analysis (PCA). For spine SBRT plans, voxel-level dose distribution is also predicted in addition to the dose-volume histogram (DVH) of spinal cord in order to explore the tradeoff between PTV coverage and spinal cord sparing by an active optical flow model (AOFM). A step-wise multiple regression method was used to select the most significant patient features which influence the dose distribution. To validate the knowledge models, the model predicted dosimetric parameters in the OARs of the validation cases are compared with the actual plan values. The difference between the model predictions and the actual values for some example dosimetric indexes are (mean±s.d.: volume in percent of OAR volume, dose in percent of prescription dose): lung V5Gy in lung IMRT plans: 0.1±6.9, Parotid median dose in head and neck IMRT plans: 0.9±5.6, Spinal cord D2% in spinal SBRT plans: 0.1±0.6. The predicted dosimetric indexes by the knowledge models can provide good estimates for those in actual plans. These models can help to improve the quality and efficiency of treatment planning.

Authors
Wu, QJ; Yuan, L; Li, T; Yin, F; Ge, Y
MLA Citation
Wu, QJ, Yuan, L, Li, T, Yin, F, and Ge, Y. "Knowledge modeling for computer aided treatment planning." January 1, 2015.
Source
scopus
Published In
Ifmbe Proceedings
Volume
51
Publish Date
2015
Start Page
425
End Page
427
DOI
10.1007/978-3-319-19387-8_103

Knowledge based automatic beam angle determination for lung IMRT planning

© Springer International Publishing Switzerland 2015. We present an efficient knowledge based automatic beam configuration determination method by utilizing patient-specific anatomy and tumor geometry information and a beam bouquet atlas. The proposed technique is based on learning the relationship between patient anatomy and beam configurations from clinical plans designed by experienced planners. The training dataset contains 60 lung IMRT plans with plan prescription dose between 45 and 70 Gy. The method involves three major steps. First, a beam bouquet atlas was established by classifying the clinical plans into 6 beam configuration groups using the k-medoids cluster analysis method. Second, a beam efficiency map was constructed to characterize the geometry of the tumor relative to the lungs, the body and the other OARs at each candidate beam direction. Finally, the beam efficiency maps of the clinical cases and the cluster assignments of their beam bouquets were paired to train a Bayesian classification model. This classification model was used to select a suitable beam bouquet from the atlas for a new case based on its beam efficiency map. This technique was validated by leave-one-out cross validation with 16 cases randomly selected from the original dataset. The dosimetric parameters (mean±S.D. in percentage of prescription dose) in the auto-beam plans and in the clinical plans, respectively, and the p-values by a paired t-test (in parenthesis) are: lung mean dose (Dmean): 16.3±9.3, 18.6±7.4 (0.48), esophagus Dmean: 28.4±18, 30.7±19.3 (0.02), Heart Dmean: 21.5±17.5,21.1±17.2 (0.76), Spinal Cord D2%: 48±23, 51.2±21.8 (0.01), PTV dose homogeneity (D2%-D99%): 22±27.4, 20.4±12.8 (0.10). The other dosimetric parameters are not statistically different. In conclusion, plans generated by the automatic beam angle determination method can achieve dosimetric quality equivalent to that of clinical plans. This method can help improve the quality and efficiency of lung IMRT planning.

Authors
Yuan, L; Ge, Y; Sheng, Y; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Sheng, Y, Yin, F, and Wu, QJ. "Knowledge based automatic beam angle determination for lung IMRT planning." January 1, 2015.
Source
scopus
Published In
Ifmbe Proceedings
Volume
51
Publish Date
2015
Start Page
440
End Page
443
DOI
10.1007/978-3-319-19387-8_107

A rapid learning approach for the knowledge modeling of radiation therapy plan

© Springer International Publishing Switzerland 2015. The purpose of this study is to implement a rapid learning method to train the knowledge models to predict the organ-at-risk (OAR) dose sparing in radiation therapy (RT) based on an array of patient anatomical features. We also aim to establish the evaluation criteria and validation method to ensure an accurate and efficient learning process. A rapid learning approach is utilized to train the knowledge models in this study. 100 clinical cancer cases in the pelvic region were retrospectively analyzed. Among them, 40 cases are low-to-intermediate risk prostate cases (Type I), 20 are high-risk prostate cases with lymph node irradiation (Type II), 40 are anorectal cancer cases (Type III). Starting from a base model for type I cases, increasing number of cases with more complex planning-target-volume (PTV)-OAR anatomies (type II and type III) were continuously added into the training case pool. The studentized residual and the leverage values are calculated as evaluation criteria at each step. The efficiency and accuracy of the learning method was quantified by the learning curve. The gEUD in the bladder and rectum are compared between the model predictions and actual values for the validation cases. The Median of the Absolute value of their Differences (MAD) are calculated for the validation cases. The MAD of the predicted OAR gEUD in all three types of cases gradually decreases when increasing number of training cases are added in training. The knowledge models learned by this method reach comparable level of prediction accuracies as in batch training mode even less training cases. The rapid learning approach is able to learn knowledge models for multiple cancer types in the pelvic region with comparable accuracy to the batch training method and with improved efficiency. This approach will facilitate the implementation of the knowledge based radiation therapy planning in clinics.

Authors
Yuan, L; Ge, Y; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Yin, F, and Wu, QJ. "A rapid learning approach for the knowledge modeling of radiation therapy plan." January 1, 2015.
Source
scopus
Published In
Ifmbe Proceedings
Volume
51
Publish Date
2015
Start Page
1492
End Page
1494
DOI
10.1007/978-3-319-19387-8_362

Defining the optimal planning target volume in image-guided stereotactic radiosurgery of brain metastases: results of a randomized trial.

PURPOSE: To identify an optimal margin about the gross target volume (GTV) for stereotactic radiosurgery (SRS) of brain metastases, minimizing toxicity and local recurrence. METHODS AND MATERIALS: Adult patients with 1 to 3 brain metastases less than 4 cm in greatest dimension, no previous brain radiation therapy, and Karnofsky performance status (KPS) above 70 were eligible for this institutional review board-approved trial. Individual lesions were randomized to 1- or 3- mm uniform expansion of the GTV defined on contrast-enhanced magnetic resonance imaging (MRI). The resulting planning target volume (PTV) was treated to 24, 18, or 15 Gy marginal dose for maximum PTV diameters less than 2, 2 to 2.9, and 3 to 3.9 cm, respectively, using a linear accelerator-based image-guided system. The primary endpoint was local recurrence (LR). Secondary endpoints included neurocognition Mini-Mental State Examination, Trail Making Test Parts A and B, quality of life (Functional Assessment of Cancer Therapy-Brain), radionecrosis (RN), need for salvage radiation therapy, distant failure (DF) in the brain, and overall survival (OS). RESULTS: Between February 2010 and November 2012, 49 patients with 80 brain metastases were treated. The median age was 61 years, the median KPS was 90, and the predominant histologies were non-small cell lung cancer (25 patients) and melanoma (8). Fifty-five, 19, and 6 lesions were treated to 24, 18, and 15 Gy, respectively. The PTV/GTV ratio, volume receiving 12 Gy or more, and minimum dose to PTV were significantly higher in the 3-mm group (all P<.01), and GTV was similar (P=.76). At a median follow-up time of 32.2 months, 11 patients were alive, with median OS 10.6 months. LR was observed in only 3 lesions (2 in the 1 mm group, P=.51), with 6.7% LR 12 months after SRS. Biopsy-proven RN alone was observed in 6 lesions (5 in the 3-mm group, P=.10). The 12-month DF rate was 45.7%. Three months after SRS, no significant change in neurocognition or quality of life was observed. CONCLUSIONS: SRS was well tolerated, with low rates of LR and RN in both cohorts. However, given the higher potential risk of RN with a 3-mm margin, a 1-mm GTV expansion is more appropriate.

Authors
Kirkpatrick, JP; Wang, Z; Sampson, JH; McSherry, F; Herndon, JE; Allen, KJ; Duffy, E; Hoang, JK; Chang, Z; Yoo, DS; Kelsey, CR; Yin, F-F
MLA Citation
Kirkpatrick, JP, Wang, Z, Sampson, JH, McSherry, F, Herndon, JE, Allen, KJ, Duffy, E, Hoang, JK, Chang, Z, Yoo, DS, Kelsey, CR, and Yin, F-F. "Defining the optimal planning target volume in image-guided stereotactic radiosurgery of brain metastases: results of a randomized trial." International journal of radiation oncology, biology, physics 91.1 (January 2015): 100-108.
PMID
25442342
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
91
Issue
1
Publish Date
2015
Start Page
100
End Page
108
DOI
10.1016/j.ijrobp.2014.09.004

Quality assurance for online adapted treatment plans: benchmarking and delivery monitoring simulation.

An important challenge facing online adaptive radiation therapy is the development of feasible and efficient quality assurance (QA). This project aimed to validate the deliverability of online adapted plans and develop a proof-of-concept online delivery monitoring system for online adaptive radiation therapy QA.The first part of this project benchmarked automatically online adapted prostate treatment plans using traditional portal dosimetry IMRT QA. The portal dosimetry QA results of online adapted plans were compared to original (unadapted) plans as well as randomly selected prostate IMRT plans from our clinic. In the second part, an online delivery monitoring system was designed and validated via a simulated treatment with intentional multileaf collimator (MLC) errors. This system was based on inputs from the dynamic machine information (DMI), which continuously reports actual MLC positions and machine monitor units (MUs) at intervals of 50 ms or less during delivery. Based on the DMI, the system performed two levels of monitoring/verification during the delivery: (1) dynamic monitoring of cumulative fluence errors resulting from leaf position deviations and visualization using fluence error maps (FEMs); and (2) verification of MLC positions against the treatment plan for potential errors in MLC motion and data transfer at each control point. Validation of the online delivery monitoring system was performed by introducing intentional systematic MLC errors (ranging from 0.5 to 2 mm) to the DMI files for both leaf banks. These DMI files were analyzed by the proposed system to evaluate the system's performance in quantifying errors and revealing the source of errors, as well as to understand patterns in the FEMs. In addition, FEMs from 210 actual prostate IMRT beams were analyzed using the proposed system to further validate its ability to catch and identify errors, as well as establish error magnitude baselines for prostate IMRT delivery.Online adapted plans were found to have similar delivery accuracy in comparison to clinical IMRT plans when validated with portal dosimetry IMRT QA. FEMs for the simulated deliveries with intentional MLC errors exhibited distinct patterns for different MLC error magnitudes and directions, indicating that the proposed delivery monitoring system is highly specific in detecting the source of errors. Implementing the proposed QA system for online adapted plans revealed excellent delivery accuracy: over 99% of leaf position differences were within 0.5 mm, and >99% of pixels in the FEMs had fluence errors within 0.5 MU. Patterns present in the FEMs and MLC control point analysis for actual patient cases agreed with the error pattern analysis results, further validating the system's ability to reveal and differentiate MLC deviations. Calculation of the fluence map based on the DMI was performed within 2 ms after receiving each DMI input.The proposed online delivery monitoring system requires minimal additional resources and time commitment to the current clinical workflow while still maintaining high sensitivity to leaf position errors and specificity to error types. The presented online delivery monitoring system therefore represents a promising QA system candidate for online adaptive radiation therapy.

Authors
Li, T; Wu, Q; Yang, Y; Rodrigues, A; Yin, F-F; Jackie Wu, Q
MLA Citation
Li, T, Wu, Q, Yang, Y, Rodrigues, A, Yin, F-F, and Jackie Wu, Q. "Quality assurance for online adapted treatment plans: benchmarking and delivery monitoring simulation." Medical physics 42.1 (January 2015): 381-390.
PMID
25563278
Source
epmc
Published In
Medical physics
Volume
42
Issue
1
Publish Date
2015
Start Page
381
End Page
390
DOI
10.1118/1.4904021

BM-17 * FINAL RESULTS OF A RANDOMIZED TRIAL TO IDENTIFY THE OPTIMAL PLANNING TARGET VOLUME IN IMAGE-GUIDED STEREOTACTIC RADIOSURGERY OF BRAIN METASTASES

Authors
Kirkpatrick, J; Wang, Z; Sampson, J; McSherry, F; Herndon, J; Allen, K; Duffy, E; Chang, Z; Hoang, J; Kelsey, C; Yoo, D; Cabrera, A; Yin, F-F
MLA Citation
Kirkpatrick, J, Wang, Z, Sampson, J, McSherry, F, Herndon, J, Allen, K, Duffy, E, Chang, Z, Hoang, J, Kelsey, C, Yoo, D, Cabrera, A, and Yin, F-F. "BM-17 * FINAL RESULTS OF A RANDOMIZED TRIAL TO IDENTIFY THE OPTIMAL PLANNING TARGET VOLUME IN IMAGE-GUIDED STEREOTACTIC RADIOSURGERY OF BRAIN METASTASES." Neuro-Oncology 16.suppl 5 (November 1, 2014): v35-v35.
Source
crossref
Published In
Neuro-Oncology
Volume
16
Issue
suppl 5
Publish Date
2014
Start Page
v35
End Page
v35
DOI
10.1093/neuonc/nou240.17

Is diaphragm motion a good surrogate for liver tumor motion?

To evaluate the relationship between liver tumor motion and diaphragm motion.Fourteen patients with hepatocellular carcinoma (10 of 14) or liver metastases (4 of 14) undergoing radiation therapy were included in this study. All patients underwent single-slice cine-magnetic resonance imaging simulations across the center of the tumor in 3 orthogonal planes. Tumor and diaphragm motion trajectories in the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions were obtained using an in-house-developed normalized cross-correlation-based tracking technique. Agreement between the tumor and diaphragm motion was assessed by calculating phase difference percentage, intraclass correlation coefficient, and Bland-Altman analysis (Diff). The distance between the tumor and tracked diaphragm area was analyzed to understand its impact on the correlation between the 2 motions.Of all patients, the mean (±standard deviation) phase difference percentage values were 7.1% ± 1.1%, 4.5% ± 0.5%, and 17.5% ± 4.5% in the SI, AP, and ML directions, respectively. The mean intraclass correlation coefficient values were 0.98 ± 0.02, 0.97 ± 0.02, and 0.08 ± 0.06 in the SI, AP, and ML directions, respectively. The mean Diff values were 2.8 ± 1.4 mm, 2.4 ± 1.1 mm, and 2.2 ± 0.5 mm in the SI, AP, and ML directions, respectively. Tumor and diaphragm motions had high concordance when the distance between the tumor and tracked diaphragm area was small.This study showed that liver tumor motion had good correlation with diaphragm motion in the SI and AP directions, indicating diaphragm motion in the SI and AP directions could potentially be used as a reliable surrogate for liver tumor motion.

Authors
Yang, J; Cai, J; Wang, H; Chang, Z; Czito, BG; Bashir, MR; Palta, M; Yin, F-F
MLA Citation
Yang, J, Cai, J, Wang, H, Chang, Z, Czito, BG, Bashir, MR, Palta, M, and Yin, F-F. "Is diaphragm motion a good surrogate for liver tumor motion?." International journal of radiation oncology, biology, physics 90.4 (November 2014): 952-958.
PMID
25223297
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
90
Issue
4
Publish Date
2014
Start Page
952
End Page
958
DOI
10.1016/j.ijrobp.2014.07.028

A hardware investigation of robotic SPECT for functional and molecular imaging onboard radiation therapy systems.

To construct a robotic SPECT system and to demonstrate its capability to image a thorax phantom on a radiation therapy flat-top couch, as a step toward onboard functional and molecular imaging in radiation therapy.A robotic SPECT imaging system was constructed utilizing a gamma camera detector (Digirad 2020tc) and a robot (KUKA KR150 L110 robot). An imaging study was performed with a phantom (PET CT Phantom(TM)), which includes five spheres of 10, 13, 17, 22, and 28 mm diameters. The phantom was placed on a flat-top couch. SPECT projections were acquired either with a parallel-hole collimator or a single-pinhole collimator, both without background in the phantom and with background at 1/10th the sphere activity concentration. The imaging trajectories of parallel-hole and pinhole collimated detectors spanned 180° and 228°, respectively. The pinhole detector viewed an off-centered spherical common volume which encompassed the 28 and 22 mm spheres. The common volume for parallel-hole system was centered at the phantom which encompassed all five spheres in the phantom. The maneuverability of the robotic system was tested by navigating the detector to trace the phantom and flat-top table while avoiding collision and maintaining the closest possible proximity to the common volume. The robot base and tool coordinates were used for image reconstruction.The robotic SPECT system was able to maneuver parallel-hole and pinhole collimated SPECT detectors in close proximity to the phantom, minimizing impact of the flat-top couch on detector radius of rotation. Without background, all five spheres were visible in the reconstructed parallel-hole image, while four spheres, all except the smallest one, were visible in the reconstructed pinhole image. With background, three spheres of 17, 22, and 28 mm diameters were readily observed with the parallel-hole imaging, and the targeted spheres (22 and 28 mm diameters) were readily observed in the pinhole region-of-interest imaging.Onboard SPECT could be achieved by a robot maneuvering a SPECT detector about patients in position for radiation therapy on a flat-top couch. The robot inherent coordinate frames could be an effective means to estimate detector pose for use in SPECT image reconstruction.

Authors
Yan, S; Bowsher, J; Tough, M; Cheng, L; Yin, F-F
MLA Citation
Yan, S, Bowsher, J, Tough, M, Cheng, L, and Yin, F-F. "A hardware investigation of robotic SPECT for functional and molecular imaging onboard radiation therapy systems." Medical physics 41.11 (November 2014): 112504-.
PMID
25370663
Source
epmc
Published In
Medical physics
Volume
41
Issue
11
Publish Date
2014
Start Page
112504
DOI
10.1118/1.4898121

Investigation of sagittal image acquisition for 4D-MRI with body area as respiratory surrogate.

The authors have recently developed a novel 4D-MRI technique for imaging organ respiratory motion employing cine acquisition in the axial plane and using body area (BA) as a respiratory surrogate. A potential disadvantage associated with axial image acquisition is the space-dependent phase shift in the superior-inferior (SI) direction, i.e., different axial slice positions reach the respiratory peak at different respiratory phases. Since respiratory motion occurs mostly in the SI and anterior-posterior (AP) directions, sagittal image acquisition, which embeds motion information in these two directions, is expected to be more robust and less affected by phase-shift than axial image acquisition. This study aims to develop and evaluate a 4D-MRI technique using sagittal image acquisition.The authors evaluated axial BA and sagittal BA using both 4D-CT images (11 cancer patients) and cine MR images (6 healthy volunteers and 1 cancer patient) by comparing their corresponding space-dependent phase-shift in the SI direction (δSPS (SI)) and in the lateral direction (δSPS (LAT)), respectively. To evaluate sagittal BA 4D-MRI method, a motion phantom study and a digital phantom study were performed. Additionally, six patients who had cancer(s) in the liver were prospectively enrolled in this study. For each patient, multislice sagittal MR images were acquired for 4D-MRI reconstruction. 4D retrospective sorting was performed based on respiratory phases. Single-slice cine MRI was also acquired in the axial, coronal, and sagittal planes across the tumor center from which tumor motion trajectories in the SI, AP, and medial-lateral (ML) directions were extracted and used as references from comparison. All MR images were acquired in a 1.5 T scanner using a steady-state precession sequence (frame rate ∼ 3 frames/s).4D-CT scans showed that δSPS (SI) was significantly greater than δSPS (LAT) (p-value: 0.012); the median phase-shift was 16.9% and 7.7%, respectively. Body surface motion measurement from axial and sagittal MR cines also showed δSPS (SI) was significantly greater than δSPS (LAT). The median δSPS (SI) and δSPS (LAT) was 11.0% and 9.2% (p-value = 0.008), respectively. Tumor motion trajectories from 4D-MRI matched with those from single-slice cine MRI: the mean (±SD) absolute differences in tumor motion amplitude between the two were 1.5 ± 1.6 mm, 2.1 ± 1.9 mm, and 1.1 ± 1.0 mm in the SI, ML, and AP directions from this patient study.Space-dependent phase shift is less problematic for sagittal acquisition than for axial acquisition. 4D-MRI using sagittal acquisition was successfully carried out in patients with hepatic tumors.

Authors
Liu, Y; Yin, F-F; Chang, Z; Czito, BG; Palta, M; Bashir, MR; Qin, Y; Cai, J
MLA Citation
Liu, Y, Yin, F-F, Chang, Z, Czito, BG, Palta, M, Bashir, MR, Qin, Y, and Cai, J. "Investigation of sagittal image acquisition for 4D-MRI with body area as respiratory surrogate." Medical physics 41.10 (October 2014): 101902-.
PMID
25281954
Source
epmc
Published In
Medical physics
Volume
41
Issue
10
Publish Date
2014
Start Page
101902
DOI
10.1118/1.4894726

Automatic Determination of Beam Angles in Lung IMRT planning

Authors
Yuan, L; Ge, Y; Yin, F; Li, Y; Sheng, Y; Kelsey, CR; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Yin, F, Li, Y, Sheng, Y, Kelsey, CR, and Wu, QJ. "Automatic Determination of Beam Angles in Lung IMRT planning." September 1, 2014.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
90
Publish Date
2014
Start Page
S105
End Page
S106

On the feasibility of polyurethane based 3D dosimeters with optical CT for dosimetric verification of low energy photon brachytherapy seeds.

To investigate the feasibility of and challenges yet to be addressed to measure dose from low energy (effective energy <50 keV) brachytherapy sources (Pd-103, Cs-131, and I-125) using polyurethane based 3D dosimeters with optical CT.The authors' evaluation used the following sources: models 200 (Pd-103), CS-1 Rev2 (Cs-131), and 6711 (I-125). The authors used the Monte Carlo radiation transport code MCNP5, simulations with the ScanSim optical tomography simulation software, and experimental measurements with PRESAGE(®) dosimeters/optical CT to investigate the following: (1) the water equivalency of conventional (density = 1.065 g/cm(3)) and deformable (density = 1.02 g/cm(3)) formulations of polyurethane dosimeters, (2) the scatter conditions necessary to achieve accurate dosimetry for low energy photon seeds, (3) the change in photon energy spectrum within the dosimeter as a function of distance from the source in order to determine potential energy sensitivity effects, (4) the optimal delivered dose to balance optical transmission (per projection) with signal to noise ratio in the reconstructed dose distribution, and (5) the magnitude and characteristics of artifacts due to the presence of a channel in the dosimeter. Monte Carlo simulations were performed using both conventional and deformable dosimeter formulations. For verification, 2.8 Gy at 1 cm was delivered in 92 h using an I-125 source to a PRESAGE(®) dosimeter with conventional formulation and a central channel with 0.0425 cm radius for source placement. The dose distribution was reconstructed with 0.02 and 0.04 cm(3) voxel size using the Duke midsized optical CT scanner (DMOS).While the conventional formulation overattenuates dose from all three sources compared to water, the current deformable formulation has nearly water equivalent attenuation properties for Cs-131 and I-125, while underattenuating for Pd-103. The energy spectrum of each source is relatively stable within the first 5 cm especially for I-125. The inherent assumption of radial symmetry in the TG43 geometry leads to a linear increase in sample points within the 3D dosimeter as a function of distance away from the source, which partially offsets the decreasing signal. Simulations of dose reconstruction using optical CT showed the feasibility of reconstructing dose out to a radius of 10 cm without saturating projection images using an optimal dose and high dynamic range scanning; the simulations also predicted that reconstruction artifacts at the channel surface due to a small discrepancy in refractive index should be negligible. Agreement of the measured with calculated radial dose function for I-125 was within 5% between 0.3 and 2.5 cm from the source, and the median difference of measured from calculated anisotropy function was within 5% between 0.3 and 2.0 cm from the source.3D dosimetry using polyurethane dosimeters with optical CT looks to be a promising application to verify dosimetric distributions surrounding low energy brachytherapy sources.

Authors
Adamson, J; Yang, Y; Juang, T; Chisholm, K; Rankine, L; Adamovics, J; Yin, FF; Oldham, M
MLA Citation
Adamson, J, Yang, Y, Juang, T, Chisholm, K, Rankine, L, Adamovics, J, Yin, FF, and Oldham, M. "On the feasibility of polyurethane based 3D dosimeters with optical CT for dosimetric verification of low energy photon brachytherapy seeds." Medical physics 41.7 (July 2014): 071705-.
PMID
24989374
Source
epmc
Published In
Medical physics
Volume
41
Issue
7
Publish Date
2014
Start Page
071705
DOI
10.1118/1.4883779

Review of treatment assessment using DCE-MRI in breast cancer radiation therapy.

As a noninvasive functional imaging technique, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is being used in oncology to measure properties of tumor microvascular structure and permeability. Studies have shown that parameters derived from certain pharmacokinetic models can be used as imaging biomarkers for tumor treatment response. The use of DCE-MRI for quantitative and objective assessment of radiation therapy has been explored in a variety of methods and tumor types. However, due to the complexity in imaging technology and divergent outcomes from different pharmacokinetic approaches, the method of using DCE-MRI in treatment assessment has yet to be standardized, especially for breast cancer. This article reviews the basic principles of breast DCE-MRI and recent studies using DCE-MRI in treatment assessment. Technical and clinical considerations are emphasized with specific attention to assessment of radiation treatment response.

Authors
Wang, C-H; Yin, F-F; Horton, J; Chang, Z
MLA Citation
Wang, C-H, Yin, F-F, Horton, J, and Chang, Z. "Review of treatment assessment using DCE-MRI in breast cancer radiation therapy." World journal of methodology 4.2 (June 26, 2014): 46-58. (Review)
PMID
25332905
Source
epmc
Published In
World journal of methodology
Volume
4
Issue
2
Publish Date
2014
Start Page
46
End Page
58
DOI
10.5662/wjm.v4.i2.46

Four-dimensional magnetic resonance imaging using axial body area as respiratory surrogate: Initial patient results

Purpose To evaluate the feasibility of a retrospective binning technique for 4-dimensional magnetic resonance imaging (4D-MRI) using body area (BA) as a respiratory surrogate. Methods and Materials Seven patients with hepatocellular carcinoma (4 of 7) or liver metastases (3 of 7) were enrolled in an institutional review board-approved prospective study. All patients were simulated with both computed tomography (CT) and MRI to acquire 3-dimensinal and 4D images for treatment planning. Multiple-slice multiple-phase cine-MR images were acquired in the axial plane for 4D-MRI reconstruction. Image acquisition time per slice was set to 10-15 seconds. Single-slice 2-dimensinal cine-MR images were also acquired across the center of the tumor in orthogonal planes. Tumor motion trajectories from 4D-MRI, cine-MRI, and 4D-CT were analyzed in the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions, respectively. Their correlation coefficients (CC) and differences in tumor motion amplitude were determined. Tumor-to-liver contrast-to-noise ratio (CNR) was measured and compared between 4D-CT, 4D-MRI, and conventional T2-weighted fast spin echo MRI. Results The means (±standard deviations) of CC comparing 4D-MRI with cine-MRI were 0.97 ± 0.03, 0.97 ± 0.02, and 0.99 ± 0.04 in SI, AP, and ML directions, respectively. The mean differences were 0.61 ± 0.17 mm, 0.32 ± 0.17 mm, and 0.14 ± 0.06 mm in SI, AP, and ML directions, respectively. The means of CC comparing 4D-MRI and 4D-CT were 0.95 ± 0.02, 0.94 ± 0.02, and 0.96 ± 0.02 in SI, AP, and ML directions, respectively. The mean differences were 0.74 ± 0.02 mm, 0.33 ± 0.13 mm, and 0.18 ± 0.07 mm in SI, AP, and ML directions, respectively. The mean tumor-to-tissue CNRs were 2.94 ± 1.51, 19.44 ± 14.63, and 39.47 ± 20.81 in 4D-CT, 4D-MRI, and T2-weighted MRI, respectively. Conclusions The preliminary evaluation of our 4D-MRI technique results in oncologic patients demonstrates its potential usefulness to accurately measure tumor respiratory motion with improved tumor CNR compared with 4D-CT. © 2014 Elsevier Inc. All rights reserved.

Authors
Yang, J; Cai, J; Wang, H; Chang, Z; Czito, BG; Bashir, MR; Yin, FF
MLA Citation
Yang, J, Cai, J, Wang, H, Chang, Z, Czito, BG, Bashir, MR, and Yin, FF. "Four-dimensional magnetic resonance imaging using axial body area as respiratory surrogate: Initial patient results." International Journal of Radiation Oncology Biology Physics 88.4 (March 15, 2014): 907-912.
Source
scopus
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
88
Issue
4
Publish Date
2014
Start Page
907
End Page
912
DOI
10.1016/j.ijrobp.2013.11.245

RTOG 0631 phase 2/3 study of image guided stereotactic radiosurgery for localized (1-3) spine metastases: Phase 2 results

Purpose: The phase 2 component of Radiation Therapy Oncology Group (RTOG) 0631 assessed the feasibility and safety of spine radiosurgery (SRS) for localized spine metastases in a cooperative group setting. Methods and Materials: Patients with 1-3 spine metastasis with a Numerical Rating Pain Scale (NRPS) score ≥. 5 received 16 Gy single fraction SRS. The primary endpoint was SRS feasibility: image guidance radiation therapy (IGRT) targeting accuracy ≤. 2 mm, target volume coverage > . 90% of prescription dose, maintaining spinal cord dose constraints (10 Gy to ≤. 10% of the cord volume from 5-6 mm above to 5-6 mm below the target or absolute spinal cord volume < 0.35 cc) and other normal tissue dose constraints. A feasibility success rate < 70% was considered unacceptable for continuation of the phase 3 component. Based on the 1-sample exact binomial test with α = 0.10 (1-sided), 41 patients were required. Acute toxicity was assessed using the National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. Results: Sixty-five institutions were credentialed with spine phantom dosimetry and IGRT compliance. Forty-six patients were accrued, and 44 were eligible. There were 4 cervical, 21 thoracic, and 19 lumbar sites. Median NRPS was 7 at presentation. Final pretreatment rapid review was approved in 100%. Accuracy of image guided SRS targeting was in compliance with the protocol in 95%. The target coverage and spinal cord dose constraint were in accordance with the protocol requirements in 100% and 97%. Overall compliance for other normal tissue constraints was per protocol in 74%. There were no cases of grade 4-5 acute treatment-related toxicity. Conclusions: The phase 2 results demonstrate the feasibility and accurate use of SRS to treat spinal metastases, with rigorous quality control, in a cooperative group setting. The planned RTOG 0631 phase 3 component will proceed to compare pain relief and quality of life between SRS and external beam radiation therapy. © 2014 American Society for Radiation Oncology.

Authors
Ryu, S; Pugh, SL; Gerszten, PC; Yin, FF; Timmerman, RD; Hitchcock, YJ; Movsas, B; Kanner, AA; Berk, LB; Followill, DS; Kachnic, LA
MLA Citation
Ryu, S, Pugh, SL, Gerszten, PC, Yin, FF, Timmerman, RD, Hitchcock, YJ, Movsas, B, Kanner, AA, Berk, LB, Followill, DS, and Kachnic, LA. "RTOG 0631 phase 2/3 study of image guided stereotactic radiosurgery for localized (1-3) spine metastases: Phase 2 results." Practical Radiation Oncology 4.2 (March 1, 2014): 76-81.
Source
scopus
Published In
Practical Radiation Oncology
Volume
4
Issue
2
Publish Date
2014
Start Page
76
End Page
81
DOI
10.1016/j.prro.2013.05.001

Four-dimensional magnetic resonance imaging using axial body area as respiratory surrogate: initial patient results.

To evaluate the feasibility of a retrospective binning technique for 4-dimensional magnetic resonance imaging (4D-MRI) using body area (BA) as a respiratory surrogate.Seven patients with hepatocellular carcinoma (4 of 7) or liver metastases (3 of 7) were enrolled in an institutional review board-approved prospective study. All patients were simulated with both computed tomography (CT) and MRI to acquire 3-dimensional and 4D images for treatment planning. Multiple-slice multiple-phase cine-MR images were acquired in the axial plane for 4D-MRI reconstruction. Image acquisition time per slice was set to 10-15 seconds. Single-slice 2-dimensional cine-MR images were also acquired across the center of the tumor in orthogonal planes. Tumor motion trajectories from 4D-MRI, cine-MRI, and 4D-CT were analyzed in the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions, respectively. Their correlation coefficients (CC) and differences in tumor motion amplitude were determined. Tumor-to-liver contrast-to-noise ratio (CNR) was measured and compared between 4D-CT, 4D-MRI, and conventional T2-weighted fast spin echo MRI.The means (± standard deviations) of CC comparing 4D-MRI with cine-MRI were 0.97 ± 0.03, 0.97 ± 0.02, and 0.99 ± 0.04 in SI, AP, and ML directions, respectively. The mean differences were 0.61 ± 0.17 mm, 0.32 ± 0.17 mm, and 0.14 ± 0.06 mm in SI, AP, and ML directions, respectively. The means of CC comparing 4D-MRI and 4D-CT were 0.95 ± 0.02, 0.94 ± 0.02, and 0.96 ± 0.02 in SI, AP, and ML directions, respectively. The mean differences were 0.74 ± 0.02 mm, 0.33 ± 0.13 mm, and 0.18 ± 0.07 mm in SI, AP, and ML directions, respectively. The mean tumor-to-tissue CNRs were 2.94 ± 1.51, 19.44 ± 14.63, and 39.47 ± 20.81 in 4D-CT, 4D-MRI, and T2-weighted MRI, respectively.The preliminary evaluation of our 4D-MRI technique results in oncologic patients demonstrates its potential usefulness to accurately measure tumor respiratory motion with improved tumor CNR compared with 4D-CT.

Authors
Yang, J; Cai, J; Wang, H; Chang, Z; Czito, BG; Bashir, MR; Yin, F-F
MLA Citation
Yang, J, Cai, J, Wang, H, Chang, Z, Czito, BG, Bashir, MR, and Yin, F-F. "Four-dimensional magnetic resonance imaging using axial body area as respiratory surrogate: initial patient results." International journal of radiation oncology, biology, physics 88.4 (March 2014): 907-912.
PMID
24444759
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
88
Issue
4
Publish Date
2014
Start Page
907
End Page
912
DOI
10.1016/j.ijrobp.2013.11.245

Dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer.

To quantitatively evaluate dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer. Overall, 11 lung SBRT patients (8 female and 3 male; mean age: 75.0 years) with medially located tumors were included. Treatment plans with simulated rotational offsets of 1°, 3°, and 5° in roll, yaw, and pitch were generated and compared with the original plans. Both clockwise and counterclockwise rotations were investigated. The following dosimetric metrics were quantitatively evaluated: planning target volume coverage (PTV V100%), max PTV dose (PTV Dmax), percentage prescription dose to 0.35cc of cord (cord D0.35cc), percentage prescription dose to 0.35cc and 5cc of esophagus (esophagus D0.35cc and D5cc), and volume of the lungs receiving at least 20Gy (lung V20). Statistical significance was tested using Wilcoxon signed rank test at the significance level of 0.05. Overall, small differences were found in all dosimetric matrices at all rotational offsets: 95.6% of differences were < 1% or < 1Gy. Of all rotational offsets, largest change in PTV V100%, PTV Dmax, cord D0.35cc, esophagus D0.35cc, esophagus D5cc, and lung V20 was - 8.36%, - 6.06%, 11.96%, 8.66%, 6.02%, and - 0.69%, respectively. No significant correlation was found between any dosimetric change and tumor-to-cord/esophagus distances (R(2) range: 0 to 0.44). Larger dosimetric changes and intersubject variations were observed at larger rotational offsets. Small dosimetric differences were found owing to rotational offsets up to 5° in lung SBRT for medially located tumors. Larger intersubject variations were observed at larger rotational offsets.

Authors
Yang, Y; Catalano, S; Kelsey, CR; Yoo, DS; Yin, F-F; Cai, J
MLA Citation
Yang, Y, Catalano, S, Kelsey, CR, Yoo, DS, Yin, F-F, and Cai, J. "Dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer." Medical dosimetry : official journal of the American Association of Medical Dosimetrists 39.1 (March 2014): 117-121.
PMID
24485056
Source
epmc
Published In
Medical Dosimetry
Volume
39
Issue
1
Publish Date
2014
Start Page
117
End Page
121
DOI
10.1016/j.meddos.2013.11.002

Incorporating single-side sparing in models for predicting parotid dose sparing in head and neck IMRT.

Sparing of single-side parotid gland is a common practice in head-and-neck (HN) intensity modulated radiation therapy (IMRT) planning. It is a special case of dose sparing tradeoff between different organs-at-risk. The authors describe an improved mathematical model for predicting achievable dose sparing in parotid glands in HN IMRT planning that incorporates single-side sparing considerations based on patient anatomy and learning from prior plan data.Among 68 HN cases analyzed retrospectively, 35 cases had physician prescribed single-side parotid sparing preferences. The single-side sparing model was trained with cases which had single-side sparing preferences, while the standard model was trained with the remainder of cases. A receiver operating characteristics (ROC) analysis was performed to determine the best criterion that separates the two case groups using the physician's single-side sparing prescription as ground truth. The final predictive model (combined model) takes into account the single-side sparing by switching between the standard and single-side sparing models according to the single-side sparing criterion. The models were tested with 20 additional cases. The significance of the improvement of prediction accuracy by the combined model over the standard model was evaluated using the Wilcoxon rank-sum test.Using the ROC analysis, the best single-side sparing criterion is (1) the predicted median dose of one parotid is higher than 24 Gy; and (2) that of the other is higher than 7 Gy. This criterion gives a true positive rate of 0.82 and a false positive rate of 0.19, respectively. For the bilateral sparing cases, the combined and the standard models performed equally well, with the median of the prediction errors for parotid median dose being 0.34 Gy by both models (p = 0.81). For the single-side sparing cases, the standard model overestimates the median dose by 7.8 Gy on average, while the predictions by the combined model differ from actual values by only 2.2 Gy (p = 0.005). Similarly, the sum of residues between the modeled and the actual plan DVHs is the same for the bilateral sparing cases by both models (p = 0.67), while the standard model predicts significantly higher DVHs than the combined model for the single-side sparing cases (p = 0.01).The combined model for predicting parotid sparing that takes into account single-side sparing improves the prediction accuracy over the previous model.

Authors
Yuan, L; Wu, QJ; Yin, F-F; Jiang, Y; Yoo, D; Ge, Y
MLA Citation
Yuan, L, Wu, QJ, Yin, F-F, Jiang, Y, Yoo, D, and Ge, Y. "Incorporating single-side sparing in models for predicting parotid dose sparing in head and neck IMRT." Medical physics 41.2 (February 2014): 021728-.
PMID
24506619
Source
epmc
Published In
Medical physics
Volume
41
Issue
2
Publish Date
2014
Start Page
021728
DOI
10.1118/1.4862075

A limited-angle intrafraction verification (LIVE) system for radiation therapy.

Currently, no 3D or 4D volumetric x-ray imaging techniques are available for intrafraction verification of target position during actual treatment delivery or in-between treatment beams, which is critical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. This study aims to develop a limited-angle intrafraction verification (LIVE) system to use prior information, deformation models, and limited angle kV-MV projections to verify target position intrafractionally.The LIVE system acquires limited-angle kV projections simultaneously during arc treatment delivery or in-between static 3D/IMRT treatment beams as the gantry moves from one beam to the next. Orthogonal limited-angle MV projections are acquired from the beam's eye view (BEV) exit fluence of arc treatment beam or in-between static beams to provide additional anatomical information. MV projections are converted to kV projections using a linear conversion function. Patient prior planning CT at one phase is used as the prior information, and the on-board patient volume is considered as a deformation of the prior images. The deformation field is solved using the data fidelity constraint, a breathing motion model extracted from the planning 4D-CT based on principal component analysis (PCA) and a free-form deformation (FD) model. LIVE was evaluated using a 4D digital extended cardiac torso phantom (XCAT) and a CIRS 008A dynamic thoracic phantom. In the XCAT study, patient breathing pattern and tumor size changes were simulated from CT to treatment position. In the CIRS phantom study, the artificial target in the lung region experienced both size change and position shift from CT to treatment position. Varian Truebeam research mode was used to acquire kV and MV projections simultaneously during the delivery of a dynamic conformal arc plan. The reconstruction accuracy was evaluated by calculating the 3D volume percentage difference (VPD) and the center of mass (COM) difference of the tumor in the true on-board images and reconstructed images.In both simulation and phantom studies, LIVE achieved substantially better reconstruction accuracy than reconstruction using PCA or FD deformation model alone. In the XCAT study, the average VPD and COM differences among different patient scenarios for LIVE system using orthogonal 30° scan angles were 4.3% and 0.3 mm when using kV+BEV MV. Reducing scan angle to 15° increased the average VPD and COM differences to 15.1% and 1.7 mm. In the CIRS phantom study, the VPD and COM differences for the LIVE system using orthogonal 30° scan angles were 6.4% and 1.4 mm. Reducing scan angle to 15° increased the VPD and COM differences to 51.9% and 3.8 mm.The LIVE system has the potential to substantially improve intrafraction target localization accuracy by providing volumetric verification of tumor position simultaneously during arc treatment delivery or in-between static treatment beams. With this improvement, LIVE opens up a new avenue for margin reduction and dose escalation in both fractionated treatments and SRS and SBRT treatments.

Authors
Ren, L; Zhang, Y; Yin, F-F
MLA Citation
Ren, L, Zhang, Y, and Yin, F-F. "A limited-angle intrafraction verification (LIVE) system for radiation therapy." Medical physics 41.2 (February 2014): 020701-.
PMID
24506590
Source
epmc
Published In
Medical physics
Volume
41
Issue
2
Publish Date
2014
Start Page
020701
DOI
10.1118/1.4861820

Evaluating radiation-induced white matter changes in patients treated with stereotactic radiosurgery using diffusion tensor imaging: a pilot study.

Stereotactic radiosurgery (SRS) has been an effective treatment method for brain tumors; however, few data are available regarding radiation-induced white matter (WM) damage by SRS. In this work, diffusion tensor imaging (DTI) was used to investigate WM changes following SRS. Fifteen patients with gliomas were enrolled, with prescription doses ranging 18-25 Gy. Patients were scanned with magnetic resonance imaging (MRI) including DTI before and after SRS. Diffusion tensors were calculated and fiber tracking was performed. Non-irradiated WM volumes and irradiated WM volumes receiving ≥ 12 Gy and ≥ Gy were contoured as volumes of interest (VOI). Apparent diffusion coefficient (〈D〉), fractional anisotropy (FA) and number of fibers (NF) were calculated and assessed using the Wilcoxon signed-rank test. Compared with those of non-irradiated VOIs, FA and NF decreased considerably after two months of SRS in the irradiated WM VOIs. The variation in (〈D〉 was however small and was not statistically significant. The preliminary results suggested that FA and NF might potentially be more sensitive indicators than (〈D〉 in measuring radiation-induced WM changes and DTI could be a valuable tool to assess radiation-induced WM changes in SRS. Although it is still preliminary, this pilot study may be useful to provide insights for future studies.

Authors
Chang, Z; Kirkpatrick, JP; Wang, Z; Cai, J; Adamson, J; Yin, F-F
MLA Citation
Chang, Z, Kirkpatrick, JP, Wang, Z, Cai, J, Adamson, J, and Yin, F-F. "Evaluating radiation-induced white matter changes in patients treated with stereotactic radiosurgery using diffusion tensor imaging: a pilot study." Technol Cancer Res Treat 13.1 (February 2014): 21-28.
PMID
23862743
Source
pubmed
Published In
Technology in cancer research & treatment
Volume
13
Issue
1
Publish Date
2014
Start Page
21
End Page
28
DOI
10.7785/tcrt.2012.500358

Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI).

The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies including gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V10) or 20Gy (V20) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V5 and D5). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung. In terms of MU and delivery time, V-MAT is significantly more efficient for APBI than for conventional 3D-CRT and static-beam IMRT.

Authors
Qiu, J-J; Chang, Z; Horton, JK; Wu, Q-RJ; Yoo, S; Yin, F-F
MLA Citation
Qiu, J-J, Chang, Z, Horton, JK, Wu, Q-RJ, Yoo, S, and Yin, F-F. "Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)." Medical dosimetry : official journal of the American Association of Medical Dosimetrists 39.2 (January 27, 2014): 152-158.
PMID
24480375
Source
epmc
Published In
Medical Dosimetry
Volume
39
Issue
2
Publish Date
2014
Start Page
152
End Page
158
DOI
10.1016/j.meddos.2013.12.001

Uncertainties of 4-dimensional computed tomography-based tumor motion measurement for lung stereotactic body radiation therapy

Purpose: To evaluate how well tumor motion measured prior to treatment based on 4-dimensional computer tomography (4DCT) reflects actual tumor motion during beam-on throughout the course of treatment. Methods and Materials: Twenty-three patients who had lung stereotactic body radiation therapy (SBRT) treatments were retrospectively selected. All patients had 4DCT simulation for treatment planning, from which tumor motion ranges were measured (R 4DCT ). Tumor motion was monitored during treatment using megavoltage (MV) imaging. Tumor motion trajectories were extracted from cine MV images and were used to determine mean and maximum tumor motion range (Mean R MV , Max R MV ) throughout entire course of treatment. Comparison and correlations between mean and max R MV and R 4DCT were calculated. Results: On average, an insignificant difference was found between mean R MV and R 4DCT (P = .67, mean [±SD] difference = -0.7 [±1.6] mm); meanwhile a significant difference was found between Max R MV and R 4DCT (P = .03, mean [± SD] difference = 1.9 [±1.6] mm). The difference between R MV and R 4DCT was found inversely proportional to R 4DCT (Y = -0.4X + 0.6, r = 0.76). Max R MV was greater than R 4DCT in all patients; difference between the 2 showed no correlation with R 4DCT (Y = -0.02X + 1.9, r = 0.05). Correlation between Mean R MV and R 4DCT and between Max R MV and R 4DCT can be expressed as Y = 0.7X (r = 0.88) and Y = 0.8X (r = 0.50), respectively. The same analysis performed on tumors that moved less than 5 mm from 4DCT revealed the following correlations: Y = 1.3X (r = 0.83) and Y = 1.7X (r = 0.49). Conclusions: Tumor motion measured from 4DCT approximates the overall average tumor motion range, but consistently underestimates the overall maximum tumor motion range. These findings may lead to a potential strategy for managing uncertainties of 4DCT in the application of lung SBRT. © 2014 American Society for Radiation Oncology.

Authors
Zhang, F; Kelsey, CR; Yoo, D; Yin, FF; Cai, J
MLA Citation
Zhang, F, Kelsey, CR, Yoo, D, Yin, FF, and Cai, J. "Uncertainties of 4-dimensional computed tomography-based tumor motion measurement for lung stereotactic body radiation therapy." Practical Radiation Oncology 4.1 (January 1, 2014).
Source
scopus
Published In
Practical Radiation Oncology
Volume
4
Issue
1
Publish Date
2014
DOI
10.1016/j.prro.2013.02.009

Stereotactic body radiotherapy: A critical review for nonradiation oncologists

Stereotactic body radiotherapy (SBRT) involves the treatment of extracranial primary tumors or metastases with a few, high doses of ionizing radiation. In SBRT, tumor kill is maximized and dose to surrounding tissue is minimized, by precise and accurate delivery of multiple radiation beams to the target. This is particularly challenging, because extracranial lesions often move with respiration and are irregular in shape, requiring careful treatment planning and continual management of this motion and patient position during irradiation. This review presents the rationale, process workflow, and technology for the safe and effective administration of SBRT, as well as the indications, outcome, and limitations for this technique in the treatment of lung cancer, liver cancer, and metastatic disease. © 2013 American Cancer Society.

Authors
Kirkpatrick, JP; Kelsey, CR; Palta, M; Cabrera, AR; Salama, JK; Patel, P; Perez, BA; Lee, J; Yin, FF
MLA Citation
Kirkpatrick, JP, Kelsey, CR, Palta, M, Cabrera, AR, Salama, JK, Patel, P, Perez, BA, Lee, J, and Yin, FF. "Stereotactic body radiotherapy: A critical review for nonradiation oncologists." Cancer 120.7 (January 1, 2014): 942-954. (Review)
Source
scopus
Published In
Cancer
Volume
120
Issue
7
Publish Date
2014
Start Page
942
End Page
954
DOI
10.1002/cncr.28515

Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)

The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies including gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V 10 ) or 20Gy (V 20 ) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V 5 and D 5 ). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung. In terms of MU and delivery time, V-MAT is significantly more efficient for APBI than for conventional 3D-CRT and static-beam IMRT. © 2014 American Association of Medical Dosimetrists.

Authors
Qiu, JJ; Chang, Z; Horton, JK; Wu, QRJ; Yoo, S; Yin, FF
MLA Citation
Qiu, JJ, Chang, Z, Horton, JK, Wu, QRJ, Yoo, S, and Yin, FF. "Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)." Medical Dosimetry 39.2 (January 1, 2014): 152-158.
Source
scopus
Published In
Medical Dosimetry
Volume
39
Issue
2
Publish Date
2014
Start Page
152
End Page
158
DOI
10.1016/j.meddos.2013.12.001

Dynamic electron arc radiotherapy (DEAR): a feasibility study.

Compared to other radiation therapy modalities, clinical electron beam therapy has remained practically unchanged for the past few decades even though electron beams with multiple energies are widely available on most linacs. In this paper, we present the concept of dynamic electron arc radiotherapy (DEAR), a new conformal electron therapy technique with synchronized couch motion. DEAR utilizes combination of gantry rotation, couch motion, and dose rate modulation to achieve desirable dose distributions in patient. The electron applicator is kept to minimize scatter and maintain narrow penumbra. The couch motion is synchronized with the gantry rotation to avoid collision between patient and the electron cone. In this study, we investigate the feasibility of DEAR delivery and demonstrate the potential of DEAR to improve dose distributions on simple cylindrical phantoms. DEAR was delivered on Varian's TrueBeam linac in Research Mode. In conjunction with the recorded trajectory log files, mechanical motion accuracies and dose rate modulation precision were analyzed. Experimental and calculated dose distributions were investigated for different energies (6 and 9 MeV) and cut-out sizes (1×10 cm(2) and 3×10 cm(2) for a 15×15 cm(2) applicator). Our findings show that DEAR delivery is feasible and has the potential to deliver radiation dose with high accuracy (root mean square error, or RMSE of <0.1 MU, <0.1° gantry, and <0.1 cm couch positions) and good dose rate precision (1.6 MU min(-1)). Dose homogeneity within ±2% in large and curved targets can be achieved while maintaining penumbra comparable to a standard electron beam on a flat surface. Further, DEAR does not require fabrication of patient-specific shields. These benefits make DEAR a promising technique for conformal radiotherapy of superficial tumors.

Authors
Rodrigues, A; Yin, F-F; Wu, Q
MLA Citation
Rodrigues, A, Yin, F-F, and Wu, Q. "Dynamic electron arc radiotherapy (DEAR): a feasibility study." Physics in medicine and biology 59.2 (January 2014): 327-345.
PMID
24351857
Source
epmc
Published In
Physics in Medicine and Biology
Volume
59
Issue
2
Publish Date
2014
Start Page
327
End Page
345
DOI
10.1088/0031-9155/59/2/327

Onboard functional and molecular imaging: a design investigation for robotic multipinhole SPECT.

Onboard imaging-currently performed primarily by x-ray transmission modalities-is essential in modern radiation therapy. As radiation therapy moves toward personalized medicine, molecular imaging, which views individual gene expression, may also be important onboard. Nuclear medicine methods, such as single photon emission computed tomography (SPECT), are premier modalities for molecular imaging. The purpose of this study is to investigate a robotic multipinhole approach to onboard SPECT.Computer-aided design (CAD) studies were performed to assess the feasibility of maneuvering a robotic SPECT system about a patient in position for radiation therapy. In order to obtain fast, high-quality SPECT images, a 49-pinhole SPECT camera was designed which provides high sensitivity to photons emitted from an imaging region of interest. This multipinhole system was investigated by computer-simulation studies. Seventeen hot spots 10 and 7 mm in diameter were placed in the breast region of a supine female phantom. Hot spot activity concentration was six times that of background. For the 49-pinhole camera and a reference, more conventional, broad field-of-view (FOV) SPECT system, projection data were computer simulated for 4-min scans and SPECT images were reconstructed. Hot-spot localization was evaluated using a nonprewhitening forced-choice numerical observer.The CAD simulation studies found that robots could maneuver SPECT cameras about patients in position for radiation therapy. In the imaging studies, most hot spots were apparent in the 49-pinhole images. Average localization errors for 10-mm- and 7-mm-diameter hot spots were 0.4 and 1.7 mm, respectively, for the 49-pinhole system, and 3.1 and 5.7 mm, respectively, for the reference broad-FOV system.A robot could maneuver a multipinhole SPECT system about a patient in position for radiation therapy. The system could provide onboard functional and molecular imaging with 4-min scan times.

Authors
Bowsher, J; Yan, S; Roper, J; Giles, W; Yin, F-F
MLA Citation
Bowsher, J, Yan, S, Roper, J, Giles, W, and Yin, F-F. "Onboard functional and molecular imaging: a design investigation for robotic multipinhole SPECT." Medical physics 41.1 (January 2014): 010701-. (Letter)
PMID
24387490
Source
epmc
Published In
Medical physics
Volume
41
Issue
1
Publish Date
2014
Start Page
010701
DOI
10.1118/1.4845195

Stereotactic body radiotherapy: A critical review for non-radiation oncologists

Authors
Kirkpatrick, JP; Kelsey, CR; Palta, M; Cabrera, AR; Salama, JK; Patel, P; Perez, BA; Lee, J; Yin, F-F
MLA Citation
Kirkpatrick, JP, Kelsey, CR, Palta, M, Cabrera, AR, Salama, JK, Patel, P, Perez, BA, Lee, J, and Yin, F-F. "Stereotactic body radiotherapy: A critical review for non-radiation oncologists." Cancer (2014).
PMID
24382744
Source
scopus
Published In
Cancer
Publish Date
2014

RTOG 0631 phase 2/3 study of image guided stereotactic radiosurgery for localized (1-3) spine metastases: Phase 2 results

Authors
Ryu, S; Pugh, SL; Gerszten, PC; Yin, F-F; Timmerman, RD; Hitchcock, YJ; Movsas, B; Kanner, AA; Berk, LB; Followill, DS; Kachnic, LA
MLA Citation
Ryu, S, Pugh, SL, Gerszten, PC, Yin, F-F, Timmerman, RD, Hitchcock, YJ, Movsas, B, Kanner, AA, Berk, LB, Followill, DS, and Kachnic, LA. "RTOG 0631 phase 2/3 study of image guided stereotactic radiosurgery for localized (1-3) spine metastases: Phase 2 results." Practical Radiation Oncology 4.2 (2014): 76-81.
Source
scopus
Published In
Practical Radiation Oncology
Volume
4
Issue
2
Publish Date
2014
Start Page
76
End Page
81

Validity of a new optic disc grading software for use in clinical and epidemiological research

Background: To determine the reliability and agreement of a new optic disc grading software program for use in clinical, epidemiological research. Design: Reliability and agreement study. Samples: 328 monoscopic and 85 stereoscopic optic disc images. Methods: Optic disc parameters were measured using a new optic disc grading software (Singapore Optic Disc Assessment) that is based on polynomial curve-fitting algorithm. Two graders independently graded 328 monoscopic images to determine intergrader reliability. One grader regraded the images after 1 month to determine intragrader reliability. In addition, 85 stereo optic disc images were separately selected, and vertical cup-to-disc ratios were measured using both the new software and standardized Wisconsin manual stereo-grading method by the same grader 1 month apart. Intraclass correlation coefficient (ICC) and Bland-Altman plot analyses were performed. Main Outcome Measures: Optic disc parameters. Results: The intragrader and intergrader reliability for optic disc measurements using Singapore Optic Disc Assessment was high (ICC ranging from 0.82 to 0.94). The mean differences (95% limits of agreement) for intergrader vertical cup-to-disc ratio measurements were 0.00 (-0.12 to 0.13) and 0.03 (-0.15 to 0.09), respectively. The vertical cup-to-disc ratio agreement between the software and Wisconsin grading method was extremely close (ICC=0.94). The mean difference (95% limits of agreement) of vertical cup-to-disc ratio measurement between the two methods was 0.03 (-0.09 to 0.16). Conclusions: Intragrader and intergrader reliability using Singapore Optic Disc Assessment was excellent. This software was highly comparable with standardized stereo-grading method. Singapore Optic Disc Assessment is useful for grading digital optic disc images in clinical, population-based studies. © 2013 Royal Australian and New Zealand College of Ophthalmologists.

Authors
Tham, YC; Cheung, CY; Wong, TY; Baskaran, M; Liu, J; Lee, BH; Yin, F; Wong, DW; Wang, JJ; Mitchell, P; Aung, T; Cheng, CY
MLA Citation
Tham, YC, Cheung, CY, Wong, TY, Baskaran, M, Liu, J, Lee, BH, Yin, F, Wong, DW, Wang, JJ, Mitchell, P, Aung, T, and Cheng, CY. "Validity of a new optic disc grading software for use in clinical and epidemiological research." Clinical and Experimental Ophthalmology 41.9 (December 1, 2013): 842-852.
Source
scopus
Published In
Clinical & Experimental Ophthalmology
Volume
41
Issue
9
Publish Date
2013
Start Page
842
End Page
852
DOI
10.1111/ceo.12112

An efficient matrix bi-factorization alternative optimization method for low-rank matrix recovery and completion

In recent years, matrix rank minimization problems have aroused considerable interests from machine learning, data mining and computer vision communities. All of these problems can be solved via their convex relaxations which minimize the trace norm instead of the rank of the matrix, and have to be solved iteratively and involve singular value decomposition (SVD) at each iteration. Therefore, those algorithms for trace norm minimization problems suffer from high computation cost of multiple SVDs. In this paper, we propose an efficient Matrix Bi-Factorization (MBF) method to approximate the original trace norm minimization problem and mitigate the computation cost of performing SVDs. The proposed MBF method can be used to address a wide range of low-rank matrix recovery and completion problems such as low-rank and sparse matrix decomposition (LRSD), low-rank representation (LRR) and low-rank matrix completion (MC). We also present three small scale matrix trace norm models for LRSD, LRR and MC problems, respectively. Moreover, we develop two concrete linearized proximal alternative optimization algorithms for solving the above three problems. Experimental results on a variety of synthetic and real-world data sets validate the efficiency, robustness and effectiveness of our MBF method comparing with the state-of-the-art trace norm minimization algorithms. © 2013 Elsevier Ltd.

Authors
Liu, Y; Jiao, LC; Shang, F; Yin, F; Liu, F
MLA Citation
Liu, Y, Jiao, LC, Shang, F, Yin, F, and Liu, F. "An efficient matrix bi-factorization alternative optimization method for low-rank matrix recovery and completion." Neural Networks 48 (December 1, 2013): 8-18.
PMID
23891807
Source
scopus
Published In
Neural Networks
Volume
48
Publish Date
2013
Start Page
8
End Page
18
DOI
10.1016/j.neunet.2013.06.013

A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections.

PURPOSE: To develop a technique to estimate onboard 4D-CBCT using prior information and limited-angle projections for potential 4D target verification of lung radiotherapy. METHODS: Each phase of onboard 4D-CBCT is considered as a deformation from one selected phase (prior volume) of the planning 4D-CT. The deformation field maps (DFMs) are solved using a motion modeling and free-form deformation (MM-FD) technique. In the MM-FD technique, the DFMs are estimated using a motion model which is extracted from planning 4D-CT based on principal component analysis (PCA). The motion model parameters are optimized by matching the digitally reconstructed radiographs of the deformed volumes to the limited-angle onboard projections (data fidelity constraint). Afterward, the estimated DFMs are fine-tuned using a FD model based on data fidelity constraint and deformation energy minimization. The 4D digital extended-cardiac-torso phantom was used to evaluate the MM-FD technique. A lung patient with a 30 mm diameter lesion was simulated with various anatomical and respirational changes from planning 4D-CT to onboard volume, including changes of respiration amplitude, lesion size and lesion average-position, and phase shift between lesion and body respiratory cycle. The lesions were contoured in both the estimated and "ground-truth" onboard 4D-CBCT for comparison. 3D volume percentage-difference (VPD) and center-of-mass shift (COMS) were calculated to evaluate the estimation accuracy of three techniques: MM-FD, MM-only, and FD-only. Different onboard projection acquisition scenarios and projection noise levels were simulated to investigate their effects on the estimation accuracy. RESULTS: For all simulated patient and projection acquisition scenarios, the mean VPD (±S.D.)∕COMS (±S.D.) between lesions in prior images and "ground-truth" onboard images were 136.11% (±42.76%)∕15.5 mm (±3.9 mm). Using orthogonal-view 15°-each scan angle, the mean VPD∕COMS between the lesion in estimated and "ground-truth" onboard images for MM-only, FD-only, and MM-FD techniques were 60.10% (±27.17%)∕4.9 mm (±3.0 mm), 96.07% (±31.48%)∕12.1 mm (±3.9 mm) and 11.45% (±9.37%)∕1.3 mm (±1.3 mm), respectively. For orthogonal-view 30°-each scan angle, the corresponding results were 59.16% (±26.66%)∕4.9 mm (±3.0 mm), 75.98% (±27.21%)∕9.9 mm (±4.0 mm), and 5.22% (±2.12%)∕0.5 mm (±0.4 mm). For single-view scan angles of 3°, 30°, and 60°, the results for MM-FD technique were 32.77% (±17.87%)∕3.2 mm (±2.2 mm), 24.57% (±18.18%)∕2.9 mm (±2.0 mm), and 10.48% (±9.50%)∕1.1 mm (±1.3 mm), respectively. For projection angular-sampling-intervals of 0.6°, 1.2°, and 2.5° with the orthogonal-view 30°-each scan angle, the MM-FD technique generated similar VPD (maximum deviation 2.91%) and COMS (maximum deviation 0.6 mm), while sparser sampling yielded larger VPD∕COMS. With equal number of projections, the estimation results using scattered 360° scan angle were slightly better than those using orthogonal-view 30°-each scan angle. The estimation accuracy of MM-FD technique declined as noise level increased. CONCLUSIONS: The MM-FD technique substantially improves the estimation accuracy for onboard 4D-CBCT using prior planning 4D-CT and limited-angle projections, compared to the MM-only and FD-only techniques. It can potentially be used for the inter/intrafractional 4D-localization verification.

Authors
Zhang, Y; Yin, F-F; Segars, WP; Ren, L
MLA Citation
Zhang, Y, Yin, F-F, Segars, WP, and Ren, L. "A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections." Med Phys 40.12 (December 2013): 121701-.
PMID
24320487
Source
pubmed
Volume
40
Issue
12
Publish Date
2013
Start Page
121701
DOI
10.1118/1.4825097

Modeling the dosimetry of organ-at-risk in head and neck IMRT planning: An intertechnique and interinstitutional study

Authors
Lian, J; Yuan, L; Ge, Y; Chera, BS; Yoo, DP; Chang, S; Yin, F; Wu, QJ
MLA Citation
Lian, J, Yuan, L, Ge, Y, Chera, BS, Yoo, DP, Chang, S, Yin, F, and Wu, QJ. "Modeling the dosimetry of organ-at-risk in head and neck IMRT planning: An intertechnique and interinstitutional study." MEDICAL PHYSICS 40.12 (December 2013).
PMID
24320490
Source
wos-lite
Published In
Medical physics
Volume
40
Issue
12
Publish Date
2013
DOI
10.1118/1.4828788

Strategies for automatic online treatment plan reoptimization using clinical treatment planning system: a planning parameters study.

PURPOSE: Adaptive radiation therapy for prostate cancer using online reoptimization provides an improved control of interfractional anatomy variations. However, the clinical implementation of online reoptimization is currently limited by the low efficiency of current strategies and the difficulties associated with integration into the current treatment planning system. This study investigates the strategies for performing fast (~2 min) automatic online reoptimization with a clinical fluence-map-based treatment planning system; and explores the performance with different input parameters settings: dose-volume histogram (DVH) objective settings, starting stage, and iteration number (in the context of real time planning). METHODS: Simulated treatments of 10 patients were reoptimized daily for the first week of treatment (5 fractions) using 12 different combinations of optimization strategies. Options for objective settings included guideline-based RTOG objectives, patient-specific objectives based on anatomy on the planning CT, and daily-CBCT anatomy-based objectives adapted from planning CT objectives. Options for starting stages involved starting reoptimization with and without the original plan's fluence map. Options for iteration numbers were 50 and 100. The adapted plans were then analyzed by statistical modeling, and compared both in terms of dosimetry and delivery efficiency. RESULTS: All online reoptimized plans were finished within ~2 min with excellent coverage and conformity to the daily target. The three input parameters, i.e., DVH objectives, starting stage, and iteration number, contributed to the outcome of optimization nearly independently. Patient-specific objectives generally provided better OAR sparing compared to guideline-based objectives. The benefit in high-dose sparing from incorporating daily anatomy into objective settings was positively correlated with the relative change in OAR volumes from planning CT to daily CBCT. The use of the original plan fluence map as the starting stage reduced OAR dose at the mid-dose region, but increased the monitor units by 17%. Differences of only 2cc or less in OAR V50%/V70Gy/V76Gy were observed between 100 and 50 iterations. CONCLUSIONS: It is feasible to perform automatic online reoptimization in ~2 min using a clinical treatment planning system. Selecting optimal sets of input parameters is the key to achieving high quality reoptimized plans, and should be based on the individual patient's daily anatomy, delivery efficiency, and time allowed for plan adaptation.

Authors
Li, T; Wu, Q; Zhang, Y; Vergalasova, I; Lee, WR; Yin, F-F; Wu, QJ
MLA Citation
Li, T, Wu, Q, Zhang, Y, Vergalasova, I, Lee, WR, Yin, F-F, and Wu, QJ. "Strategies for automatic online treatment plan reoptimization using clinical treatment planning system: a planning parameters study." Med Phys 40.11 (November 2013): 111711-.
PMID
24320419
Source
pubmed
Volume
40
Issue
11
Publish Date
2013
Start Page
111711
DOI
10.1118/1.4823473

Evaluation of the effect of respiratory and anatomical variables on a Fourier technique for markerless, self-sorted 4D-CBCT.

A novel technique based on Fourier transform theory has been developed that directly extracts respiratory information from projections without the use of external surrogates. While the feasibility has been demonstrated with three patients, a more extensive validation is necessary. Therefore, the purpose of this work is to investigate the effects of a variety of respiratory and anatomical scenarios on the performance of the technique with the 4D digital extended cardiac torso phantom. FT-phase and FT-magnitude methods were each applied to identify peak-inspiration projections and quantitatively compared to the gold standard of visual identification. Both methods proved to be robust across the studied scenarios with average differences in respiratory phase <10% and percentage of projections assigned within 10% of the gold standard >90%, when incorporating minor modifications to region-of-interest (ROI) selection and/or low-frequency location for select cases of DA and lung percentage in the field of view of the projection. Nevertheless, in the instance where one method initially faltered, the other method prevailed and successfully identified peak-inspiration projections. This is promising because it suggests that the two methods provide complementary information to each other. To ensure appropriate clinical adaptation of markerless, self-sorted four-dimensional cone-beam CT (4D-CBCT), perhaps an optimal integration of the two methods can be developed.

Authors
Vergalasova, I; Cai, J; Giles, W; Segars, WP; Yin, FF
MLA Citation
Vergalasova, I, Cai, J, Giles, W, Segars, WP, and Yin, FF. "Evaluation of the effect of respiratory and anatomical variables on a Fourier technique for markerless, self-sorted 4D-CBCT." Phys Med Biol 58.20 (October 21, 2013): 7239-7259.
PMID
24061289
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
58
Issue
20
Publish Date
2013
Start Page
7239
End Page
7259
DOI
10.1088/0031-9155/58/20/7239

A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac.

Volumetric modulated arc therapy (VMAT) is a relatively new treatment modality for dynamic photon radiation therapy. Pre-treatment quality assurance (QA) is necessary and many efforts have been made to apply electronic portal imaging device (EPID)-based IMRT QA methods to VMAT. It is important to verify the gantry rotation speed during delivery as this is a new variable that is also modulated in VMAT. In this paper, we present a new technique to perform VMAT QA using an EPID. The method utilizes EPID cine mode and was tested on Varian TrueBeam in research mode. The cine images were acquired during delivery and converted to dose matrices after profile correction and dose calibration. A sub-arc corresponding to each cine image was extracted from the original plan and its portal image prediction was calculated. Several analyses were performed including 3D γ analysis (2D images + gantry angle axis), 2D γ analysis, and other statistical analyses. The method was applied to 21 VMAT photon plans of 3 photon energies. The accuracy of the cine image information was investigated. Furthermore, this method's sensitivity to machine delivery errors was studied. The pass rate (92.8 ± 1.4%) for 3D γ analysis was comparable to those from Delta(4) system (99.9 ± 0.1%) under similar criteria (3%, 3 mm, 5% threshold and 2° angle to agreement) at 6 MV. The recorded gantry angle and start/stop MUs were found to have sufficient accuracy for clinical QA. Machine delivery errors can be detected through combined analyses of 3D γ, gantry angle, and percentage dose difference. In summary, we have developed and validated a QA technique that can simultaneously verify the gantry angle and delivered MLC fluence for VMAT treatment.This technique is efficient and its accuracy is comparable to other QA methods.

Authors
Liu, B; Adamson, J; Rodrigues, A; Zhou, F; Yin, F-F; Wu, Q
MLA Citation
Liu, B, Adamson, J, Rodrigues, A, Zhou, F, Yin, F-F, and Wu, Q. "A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac." Phys Med Biol 58.19 (October 7, 2013): 6683-6700.
PMID
24018655
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
58
Issue
19
Publish Date
2013
Start Page
6683
End Page
6700
DOI
10.1088/0031-9155/58/19/6683

Feasibility of Using a Fourier Markerless Technique for Clinical 4D-CBCT Reconstruction

Authors
Vergalasova, I; Giles, W; Cai, J; Yin, F
MLA Citation
Vergalasova, I, Giles, W, Cai, J, and Yin, F. "Feasibility of Using a Fourier Markerless Technique for Clinical 4D-CBCT Reconstruction." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S702
End Page
S702

Incorporating Trade-Off in Knowledge Modeling of Parotid Dose Sparing in Head and Neck IMRT

Authors
Yuan, L; Wu, Q; Jiang, Y; Li, T; Yin, F; David, Y; Ge, Y
MLA Citation
Yuan, L, Wu, Q, Jiang, Y, Li, T, Yin, F, David, Y, and Ge, Y. "Incorporating Trade-Off in Knowledge Modeling of Parotid Dose Sparing in Head and Neck IMRT." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S715
End Page
S715

Quality Evaluation of an Automatic VMAT Planning Method for Head-and-Neck Cancer Cases

Authors
Pang, T; Yuan, L; Ge, Y; Jiang, Y; Das, S; Yoo, D; Yin, F; Wu, Q
MLA Citation
Pang, T, Yuan, L, Ge, Y, Jiang, Y, Das, S, Yoo, D, Yin, F, and Wu, Q. "Quality Evaluation of an Automatic VMAT Planning Method for Head-and-Neck Cancer Cases." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S581
End Page
S582

Effects of PET Reconstruction Parameters on Region-of-Interest Contouring by SUV Threshold

Authors
Li, H; Bowsher, J; Jiang, Y; Pang, T; Wu, Q; Yan, S; Czito, B; Willett, C; Yin, F
MLA Citation
Li, H, Bowsher, J, Jiang, Y, Pang, T, Wu, Q, Yan, S, Czito, B, Willett, C, and Yin, F. "Effects of PET Reconstruction Parameters on Region-of-Interest Contouring by SUV Threshold." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S340
End Page
S340

Modeling Organs at Risk Dose Sparing in Head and Neck Tomotherapy and IMRT Plans: A Comparison Study

Authors
Yuan, L; Lian, J; Chang, S; Wu, Q; Yin, F; Jiang, Y; Ge, Y
MLA Citation
Yuan, L, Lian, J, Chang, S, Wu, Q, Yin, F, Jiang, Y, and Ge, Y. "Modeling Organs at Risk Dose Sparing in Head and Neck Tomotherapy and IMRT Plans: A Comparison Study." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S624
End Page
S624

Normal Tissue Toxicity Criteria in Radiation Therapy

Authors
Jiang, Y; Yuan, L; Wu, Q; Yin, F; Ge, Y
MLA Citation
Jiang, Y, Yuan, L, Wu, Q, Yin, F, and Ge, Y. "Normal Tissue Toxicity Criteria in Radiation Therapy." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S621
End Page
S622

Quantitative Comparison of Knowledge-Guided IMRT Planning to Expert Planning for Prostate Cancer

Authors
Yang, Y; Yuan, L; Li, T; Ge, Y; Yin, F; Lee, W; Wu, Q
MLA Citation
Yang, Y, Yuan, L, Li, T, Ge, Y, Yin, F, Lee, W, and Wu, Q. "Quantitative Comparison of Knowledge-Guided IMRT Planning to Expert Planning for Prostate Cancer." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S56
End Page
S56

Intertechnique and Interinstitutional Modeling of the Dosimetry of Organs-at-Risk in Head and Neck IMRT Plans

Authors
Lian, J; Yuan, L; Ge, Y; Chera, B; Yoo, D; Chang, S; Yin, F; Wu, Q
MLA Citation
Lian, J, Yuan, L, Ge, Y, Chera, B, Yoo, D, Chang, S, Yin, F, and Wu, Q. "Intertechnique and Interinstitutional Modeling of the Dosimetry of Organs-at-Risk in Head and Neck IMRT Plans." October 1, 2013.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
2
Publish Date
2013
Start Page
S56
End Page
S56

Single Institution's Dosimetry and IGRT Analysis of Prostate SBRT

Background and purpose: To report single institution's IGRT and dosimetry analysis on the 37 Gy/5 fraction prostate SBRT clinical trial.Materials/methods: The IRB (Duke University Medical Center) approved clinical trial has treated 28 patients with stage T1-T2c prostate cancer with a regimen of 37 Gy in 5 fractions using IMRT and IGRT protocols since 2009. The clinical trial protocol requires CT/MRI imaging for the prostate delineation; a margin of 3 mm in posterior direction and 5 mm elsewhere for planning target volume (PTV); and strict dose constraints for primary organs-at-risks (OARs) including the bladder, the rectum, and the femoral heads. Rigid IGRT process is also an essential part of the protocol. Precise patient and prostate positioning and dynamic tracking of prostate motion are performed with electromagnetic localization device (Calypso) and on-board imaging (OBI) system. Initial patient and target alignment is performed based on fiducials with OBI imaging system and Calypso system. Prior to treatment, cone-beam CT (CBCT) is performed for soft tissue alignment verification. During treatment, per-beam corrections for target motion using translational couch movements is performed before irradiating each field, based on electromagnetic localization or on-board imaging localization. Dosimetric analysis on target coverage and OAR sparing is performed based on key DVH parameters corresponding to protocol guidance. IGRT analysis is focused on the average frequency and magnitude of corrections during treatment, and overall intra-fractional target drift. A margin value is derived using actual target motion data and the margin recipe from Van Herk et al., and is compared to the current one in practice. In addition, cumulative doses with and without per-beam IGRT corrections are compared to assess the benefit of online IGRT.Results: 1. No deviation has been found in 10 of 14 dosimetric constraints, with minor deviations in the rest 4 constraints.2. Online IGRT techniques including Calypso, OBI and CBCT supplement each other to create an effective and reliable system on tracking target and correcting intra-fractional motion.3. On average 1-Feb corrections have been performed per fraction, with magnitude of (0.22 ± 0.11) cm. Average target drift magnitude is (0.7 ± 1.3) mm in one direction during each fraction.4. Benefit from per-beam correction in overall review is small: most differences from no correction are < 0.1 Gy for PTV D1cc/Dmean and < 1%/1.5 cc for OAR parameters. Up to 1.5 Gy reduction was seen in PTV D99% without online correction. Largest differences for OARs are -4.1 cc and +1.6 cc in the V50% for the bladder and the rectum, respectively. However, online IGRT helps to catch unexpected significant target motion.5. Margin derived from actual target motion is 2.5 mm isotropic, consist with current practice.Conclusions: Clinical experience of the 37 Gy/5-fraction prostate SBRT from a single institution is reported. Dosimetric analysis demonstrated excellent target coverage and OAR sparing for our first 28 patients in this trial. Online IGRT techniques implemented are both effective and reliable. Per-beam correction in general provides a small benefit in dosimetry. Target motion measured by online localization devices confirms that current margin selection is adequate. © 2013 Wu et al.; licensee BioMed Central Ltd.

Authors
Wu, QJ; Li, T; Yuan, L; Yin, FF; Lee, WR
MLA Citation
Wu, QJ, Li, T, Yuan, L, Yin, FF, and Lee, WR. "Single Institution's Dosimetry and IGRT Analysis of Prostate SBRT." Radiation Oncology 8.1 (September 13, 2013).
PMID
24034234
Source
scopus
Published In
Radiation Oncology
Volume
8
Issue
1
Publish Date
2013
DOI
10.1186/1748-717X-8-215

A knowledge-based approach to improving and homogenizing intensity modulated radiation therapy planning quality among treatment centers: an example application to prostate cancer planning.

PURPOSE: Intensity modulated radiation therapy (IMRT) treatment planning can have wide variation among different treatment centers. We propose a system to leverage the IMRT planning experience of larger institutions to automatically create high-quality plans for outside clinics. We explore feasibility by generating plans for patient datasets from an outside institution by adapting plans from our institution. METHODS AND MATERIALS: A knowledge database was created from 132 IMRT treatment plans for prostate cancer at our institution. The outside institution, a community hospital, provided the datasets for 55 prostate cancer cases, including their original treatment plans. For each "query" case from the outside institution, a similar "match" case was identified in the knowledge database, and the match case's plan parameters were then adapted and optimized to the query case by use of a semiautomated approach that required no expert planning knowledge. The plans generated with this knowledge-based approach were compared with the original treatment plans at several dose cutpoints. RESULTS: Compared with the original plan, the knowledge-based plan had a significantly more homogeneous dose to the planning target volume and a significantly lower maximum dose. The volumes of the rectum, bladder, and femoral heads above all cutpoints were nominally lower for the knowledge-based plan; the reductions were significantly lower for the rectum. In 40% of cases, the knowledge-based plan had overall superior (lower) dose-volume histograms for rectum and bladder; in 54% of cases, the comparison was equivocal; in 6% of cases, the knowledge-based plan was inferior for both bladder and rectum. CONCLUSIONS: Knowledge-based planning was superior or equivalent to the original plan in 95% of cases. The knowledge-based approach shows promise for homogenizing plan quality by transferring planning expertise from more experienced to less experienced institutions.

Authors
Good, D; Lo, J; Lee, WR; Wu, QJ; Yin, F-F; Das, SK
MLA Citation
Good, D, Lo, J, Lee, WR, Wu, QJ, Yin, F-F, and Das, SK. "A knowledge-based approach to improving and homogenizing intensity modulated radiation therapy planning quality among treatment centers: an example application to prostate cancer planning." Int J Radiat Oncol Biol Phys 87.1 (September 1, 2013): 176-181.
PMID
23623460
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
87
Issue
1
Publish Date
2013
Start Page
176
End Page
181
DOI
10.1016/j.ijrobp.2013.03.015

Respiration-phase-matched digital tomosynthesis imaging for moving target verification: a feasibility study.

PURPOSE: To develop a respiration-phase-matched digital tomosynthesis (DTS) technique to monitor moving targets, and to evaluate its accuracy for various imaging parameters and anatomical characteristics. METHODS: Previously developed 3D-DTS techniques, registering onboard DTS (OB-DTS, reconstructed from onboard projections) to reference DTS (R-DTS, reconstructed from DRRs of 3D reference CT), are inadequate to monitor moving targets. The authors' proposed respiration-phase-matched DTS technique registers OB-DTS to R-DTS reconstructed from DRRs generated by the same phase images of 4D reference CT as the corresponding onboard projections. To evaluate the improved accuracy of the author's technique, the authors performed thoracic phantom studies using (1) simulation with the 4D digital extended-cardiac-torso (XCAT) phantom, and (2) experiments with an anthropomorphic motion phantom. The studies were performed for various: respiratory cycle (RC), scan angle, and fraction of RC contained therein. Also, the authors assessed the accuracy of their technique relative to target size/location, and respiration inconsistencies from the R-DTS to OB-DTS. RESULTS: In both simulation and experimental studies, the respiration-phase-matched DTS technique is significantly more accurate in determining moving target positions. For 324 different scenarios simulated by XCAT, the respiration-phase-matched DTS technique localizes the 3D target position to errors of 1.07 ± 0.57 mm (mean ± S.D.), as compared to (a) 2.58 ± 1.37 and (b) 7.37 ± 4.18 mm, for 3D-DTS using 3D reference CT of (a) average intensity projection and (b) free-breathing CT. For 60 scenarios evaluated through experimental study, the uncertainties corresponding to those above are 1.24 ± 0.87, 2.42 ± 1.80, and 5.77 ± 6.45 mm, respectively. For a given scan angle, the accuracy of respiration-phase-matched DTS technique is less dependent on RC and the fraction of RC included in the scan. Increasing scan angle improves its accuracy. For different target locations, the targets near the chest wall or in the middle of lung provide higher registration accuracy compared to those near the mediastinum and diaphragm. Larger targets provide higher registration accuracy than small targets. Different respiratory cycle inconsistencies from R-DTS to OB-DTS minimally affect the registration accuracy. Increasing the respiratory amplitude inconsistencies will decrease the accuracy. CONCLUSIONS: The respiration-phase-matched DTS is more accurate and robust in determining moving target positions than 3D-DTS. It has potential application in pretreatment setup, post-treatment analysis, and intrafractional target verification.

Authors
Zhang, Y; Ren, L; Ling, CC; Yin, F-F
MLA Citation
Zhang, Y, Ren, L, Ling, CC, and Yin, F-F. "Respiration-phase-matched digital tomosynthesis imaging for moving target verification: a feasibility study." Med Phys 40.7 (July 2013): 071723-.
PMID
23822427
Source
pubmed
Volume
40
Issue
7
Publish Date
2013
Start Page
071723
DOI
10.1118/1.4810921

SU-E-T-143: Dosimetric Characteristics of TrueBeam STx System with High Definition Multi-Leaf Collimator: Commissioning of Stereotactic Radiosurgery.

IntroductionDosimetric characteristics of one TrueBeam STx treatment unit with a 120-leaf high definition multileaf collimator (HD120MLC) are systematically measured for commissioning of stereotactic radiosurgery (SRS). Due to limited data available, it is important to make the dosimetric data available for reference.MethodsSRS commissioning data were acquired for two photon beam calculation algorithms of the treatment planning system iPlan (BrainLAB iPlan4.5): Clarkson method and Pencil Beam dose calculation (PBC) method. Major beam data required include percent depth dose (PDD), beam profile, and relative scatter factors for various field sizes. Generally, the PBC is used for HD120MLC based treatment planning, while Clarkson method is for cone-based planning. ResultsPDD, beam profile and relative scatter data for the circular cones with diameters of 4, 6.0, 7.5, 10, 12.5, 15 mm were measured for 6X flattening-filter-free (FFF) and 10X FFF. The relative scatter factors range from 1.12 to 1.45 for 6X FFF and 0.81 to 1.23 for 10XFFF. Beam penumbra of 6XFFF and 10XFFF of each the circular cone were less than 2.5 mm for the 20% to 80% criterion. PDD and relative scatter data for HD120MLC were measured for various MLC fields with corresponding jaw settings for various energy modes: 6X, 6X FFF, 10X, 10X FFF and 15X, with an MLC filed down to 5mmx5mm. The transverse and diagonal beam profiles for HD120MLC were measured at different depths to generate source function correction models in iPlan. HD120MLC leakage for open jaw and close jaw are ∼1% and 0.0% for all the energy modes. The measured HD120MLC dynamic leaf shifts are 0.15, 0.11, 0.19, 0.18, 0.21 mm for 6X, 6XFFF, 10X, 10XFFF and 15X, less than 1/2 of those of the Novalis Tx system previous published.ConclusionThe commissioning data provided us valuable insights and might be useful for future reference.

Authors
Chang, Z; Wu, Q; Yan, H; Yang, Y; Giles, W; Busselberg, C; Lipscomb, R; Yin, F
MLA Citation
Chang, Z, Wu, Q, Yan, H, Yang, Y, Giles, W, Busselberg, C, Lipscomb, R, and Yin, F. "SU-E-T-143: Dosimetric Characteristics of TrueBeam STx System with High Definition Multi-Leaf Collimator: Commissioning of Stereotactic Radiosurgery." Medical physics 40.6Part12 (June 2013): 236-237.
PMID
28518977
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part12
Publish Date
2013
Start Page
236
End Page
237
DOI
10.1118/1.4814578

SU-E-T-196: Pretreatment Patient Clinical Objective IMRT Quality Assurance Using a 3D Diode Array.

To evaluate the accuracy and sensitivity of a patient clinical objective IMRT QA tool using a 3D diode array.A 3D QA device (Delta4, Scandidos Inc.) with 2 orthogonal diode array planes was used for IMRT QA. The diode spacing is 5mm in central 6cmx6cm region and 1cm in the peripheral 20cmx20cm region. 3D volumetric dose is interpolated from the measured planar dose. The Delta4 Anatomy software (Anatomy) calculates the entrance energy fluence for each beam, which is then applied to the patient anatomy to calculate dose to the patient using a pencil-beam dose calculation algorithm. The accuracy of Anatomy was evaluated in both solid water phantom using open fields and in patient anatomy using a prostate IMRT plan. The dose calculated by Eclipse was used as the gold standard. The sensitivity of the Anatomy was also evaluated by introducing leaf positioning errors in the delivery of a spine SBRT plan.Excellent agreement between Anatomy and Eclipse was achieved for the solid water phantom with open fields. Discrepancy was observed for the PTV DVH calculated in patient anatomy using the prostate IMRT plan. This is mainly due to sharp dose fall-off outside PTV and phantom setup errors during QA. Good agreement between Anatomy and Eclipse was achieved for bladder and rectum DVH. For spine case with introduced 1cm single leaf positioning error, the traditional gamma analysis using Delta4 still showed 95% pass rate using 3%, 3mm criteria. However, Anatomy showed 40% increase of cord max dose due to this error, which was consistent with Eclipse.Patient clinical objective QA using Delta4 Anatomy can potentially provide valuable information about the clinical significance of the QA results. It can potentially catch clinically significant delivery errors that would otherwise be missed in the traditional QA process using gamma analysis. Funding from Scandidos Inc.

Authors
Ren, L; Zhang, Y; Yang, Y; Adamson, J; Yin, F
MLA Citation
Ren, L, Zhang, Y, Yang, Y, Adamson, J, and Yin, F. "SU-E-T-196: Pretreatment Patient Clinical Objective IMRT Quality Assurance Using a 3D Diode Array." Medical physics 40.6Part13 (June 2013): 249-.
PMID
28519276
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part13
Publish Date
2013
Start Page
249
DOI
10.1118/1.4814631

WE-G-108-08: A Novel Technique for VMAT QA with EPID in Cine Mode On Varian TrueBeam.

Volumetric modulated arc therapy (VMAT) is a relatively new treatment modality for dynamic photon radiation therapy. Pre-treatment quality assurance (QA) is necessary and many efforts have been taken to apply electronic portal imaging device (EPID) based IMRT QA methods to VMAT. It is important to verify the gantry angles during delivery as this is new variable that is also modulated in VMAT. The purpose of this study is to develop and validate a new technique that is accurate and efficient to perform VMAT QA using EPID.The method utilized EPID cine mode and was tested on Varian TrueBeam in research mode. The cine images were acquired during delivery and converted to dose matrices after profile correction and dose calibration. Sub-arc corresponding to each cine image was extracted from the original plan and its portal image prediction was calculated. Several analyses were performed including 3D γ analysis (2D images plus gantry angle axis), 2D γ analysis, and other statistical analyses. The method was applied to 21 VMAT beams of 6MV photons and the accuracy of cine image information was investigated. Furthermore, this method's sensitivity to machine delivery errors was studied.The pass rate (97.8±1.1%) for 3D γ analysis was comparable to that from Delta4 (99.9±0.1%) under similar criteria (3%, 3mm, 5% threshold and 3°angle to agreement). The recorded gantry angle and start/stop MUs were found to have sufficient accuracy for clinical QA. Machine delivery errors can be detected through combined analyses of 3D γ index, gantry angle, and percentage dose difference.We have developed and validated a QA technique that can simultaneously verify the gantry angle and delivered MLC fluence for VMAT treatment. The method is efficient and its accuracy is comparable to other methods. B Liu's work was supported by the Chinese Scholarship Council.

Authors
Liu, B; Adamson, J; Rodrigues, A; Zhou, F; Yin, F; Wu, Q
MLA Citation
Liu, B, Adamson, J, Rodrigues, A, Zhou, F, Yin, F, and Wu, Q. "WE-G-108-08: A Novel Technique for VMAT QA with EPID in Cine Mode On Varian TrueBeam." Medical physics 40.6Part30 (June 2013): 502-.
PMID
28519131
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part30
Publish Date
2013
Start Page
502
DOI
10.1118/1.4815632

TU-G-134-01: 4D-MRI Using Body Area as Internal Respiratory Surrogate: Initial Patient Results.

We have previously developed a novel 4D-MRI technique using body area (BA) as internal respiratory surrogate. This study is to demonstrate our initial patient results via validating the accuracy of tumor motion measurements and the improvement of tumor-to-tissue contrast-to-signal ratio (CNR) in the 4D-MRI.Five patients with cancer (s) in the liver were enrolled in an IRB-approved study. All patients underwent 3D/4D CT and MR simulation for treatment planning. 4D-MRI image were generated by firstly acquiring multiple-slice multiple-phase cine-MR images in the axial plane and then retrospectively binning the images based on respiratory phases. Respiratory signals were determined by tracking changes of the BA of axial MR images. Single-slice 2D cine MR images were also acquired across the center of the tumor in orthogonal planes (axial, sagittal, and coronal). For data analysis, tumor motion trajectories in the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions, were determined from 4D-MRI and compared to those determined from cine-MR images, which were used as references. The correlation coefficients (CC) and the differences in tumor motion amplitude were determined between the two. Tumor-to-liver CNR was compared between 4D-MRI and 4D-CT.4D-MRI clearly revealed respiratory motion in all patients. Tumor motion trajectories were comparable between 4D-MRI and cine-MR: the mean (± standard deviation (SD)) CC was 0.97(±0.03), 0.97(±0.02), and 0.99(±0.04) in the SI, AP and ML directions, respectively. The mean (±SD) difference in tumor motion amplitude was 0.61(±0.17)mm, 0.32(±0.17)mm, 0.14(±0.06)mm in the SI, AP and ML directions, respectively. The mean tumor-to-tissue CNR were improved from 1.52(±2.04) in 4D-CT images to 7.57(±5.64) in 4D-MRIs.4D-MRI using BA as respiratory surrogate and axial image acquisition has been successfully demonstrated in patients. It is a promising technique for more accurately imaging tumor respiratory motion with improved soft-tissue contrast. This work is partly supported by funding from NIH (1R21CA165384-01A1) and a research grant from the Golfers Against Cancer (GAC) Foundation.

Authors
Yang, J; Yin, F; Wang, H; Chang, Z; Czito, B; Bashir, M; Cai, J
MLA Citation
Yang, J, Yin, F, Wang, H, Chang, Z, Czito, B, Bashir, M, and Cai, J. "TU-G-134-01: 4D-MRI Using Body Area as Internal Respiratory Surrogate: Initial Patient Results." Medical physics 40.6Part28 (June 2013): 460-.
PMID
28519931
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part28
Publish Date
2013
Start Page
460
DOI
10.1118/1.4815479

WE-C-116-07: Tumor Enhancement Using Deformable Image Registration for Four-Dimensional Magnetic Resonance Imaging (4D-MRI): A Feasibility Study.

We have previously developed a 4D-MRI technique using the fast imaging sequence employing steady-state acquisition (FIESTA) sequence, which has suboptimal tumor-to-tissue contrast-to-noise ratio (CNR) due to its T2*/T1 weighting. This study investigated the feasibility of enhancing the tumor-to-tissue CNR using deformable image registration (DIR).Five patients with cancers in the liver were included in an IRB-approved study. 4D-MRI images were acquired on a 1.5T GE scanner and reconstructed off line using in-house developed program. All patients were also imaged with a T2-w fast recovery fast spin-echo (FRFSE) sequence at the end-of-exhalation phase. Deformation vectors between respiratory phases of the 4D-MRI were determined using commercial software. Pseudo 'enhanced' 4D-MRI was then generated by applying the deformation vectors to the T2-w FRFSE MR images. Motion trajectories of tumor and diaphragm and tumor-to-tissue CNR were compared between the original T2*/T1-w 4D-MRI and the 'enhanced' T2-w 4D-MRI. To validate our method, we performed a simulation study based on a 4D digital human phantom. MR images with T2*/T1-w and T2-w with were generated by assigning organ intensities corresponding to those in FIESTA and FRFSE images, respectively.In the phantom study, motion trajectories of the hypothesized 'tumor' matched excellently between the original T2*/T1-w 4D-MRI and the 'enhanced' T2-w 4D-MRI. Mean(±SD) absolute difference in motion amplitude was 0.66 (±0.62) mm. In the patient study, tumor and diaphragm motion trajectories closely matched between the two 4D-MRIs: mean correlation coefficient was great than 0.97 in all directions; the mean (±SD) absolute difference in motion amplitude was smaller than 0.55(±0.19) mm. Tumor-to-tissue CNR was significantly improved from 7.57(±5.6) in the original 4D-MRI to 23.75(±15.8) in the 'enhanced' 4D-MRI.It is feasible to improve tumor-to-tissue CNR of T2*/T1-w 4D-MRI using the DIR method. The 'enhanced' 4D-MRI retained comparable tumor motion information as the original 4D-MRI. This work is partly supported by funding from NIH (1R21CA165384-01A1) and a research grant from the Golfers Against Cancer (GAC) Foundation.

Authors
Yang, J; Cai, J; Wang, H; Chang, Z; Czito, B; Bashir, M; Yin, F
MLA Citation
Yang, J, Cai, J, Wang, H, Chang, Z, Czito, B, Bashir, M, and Yin, F. "WE-C-116-07: Tumor Enhancement Using Deformable Image Registration for Four-Dimensional Magnetic Resonance Imaging (4D-MRI): A Feasibility Study." Medical physics 40.6Part29 (June 2013): 485-.
PMID
28518641
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part29
Publish Date
2013
Start Page
485
DOI
10.1118/1.4815569

WE-G-134-04: Four-Dimensional Dual Cone-Beam CT (4D-DCBCT): Preliminary Experimental Results.

One of the major challenges for clinical implementation of 4D-CBCT is long scan time. This study aims to develop a 4D-DCBCT technique to improve the efficiency of 4D imaging (for motion management in radiation therapy).A bench-top DCBCT system, which consists of two orthogonal 40x30cm flat panel detectors and two conventional x-ray tubes with two individual high-voltage generators, sharing the same rotational axis, was used to develop the technique. The x-ray source to detector distance was 150 cm and x-ray source to rotational axis distance was 100 cm for both subsystems. The dual CBCT system utilized 110° of projection data from one detector and 90° from the other, as opposed to a single CBCT utilizing 200° of projection data per each detector. Motion phantom studies were conducted to validate the efficiencies by comparing 4D images generated from 4D-DCBCT and 4D-CBCT. First, a simple sinusoidal profile was used to confirm the scan time reduction. Next, both irregular sinusoidal and patient-derived profiles were used to investigate the advantage of temporally correlated orthogonal projections due to a reduced scan time. Normalized mutual information (NMI) between 4D-DCBCT and 4D-CBCT was used for quantitative evaluation.For the simple sinusoidal profile, the average NMI for ten phases between two single 4D-CBCTs was 0.336, indicating the maximum NMI that can be achieved for this study. The average NMIs between 4D-DCBCT and each single 4D-CBCT were 0.331 and 0.320. For both irregular sinusoidal and patient-derived profiles, 4D-DCBCT generated phase images with less motion blurring when compared with single 4D-CBCT.The 4D-DCBCT provides an efficient 4D imaging technique for motion management. The scan time is approximately reduced by a factor of two. The temporally correlated orthogonal projections improved the image blur across 4D phase images.

Authors
Li, H; Vergalasova, I; Giles, W; Bowsher, J; Yin, F
MLA Citation
Li, H, Vergalasova, I, Giles, W, Bowsher, J, and Yin, F. "WE-G-134-04: Four-Dimensional Dual Cone-Beam CT (4D-DCBCT): Preliminary Experimental Results." Medical physics 40.6Part31 (June 2013): 512-.
PMID
28519695
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part31
Publish Date
2013
Start Page
512
DOI
10.1118/1.4815673

WE-A-500-01: Quality Control of Lung SBRT: Minimizing Uncertainties From Simulation to Treatment.

Stringent quality control is critical to the success of lung SBRT. However, uncertainties exist in each step of the lung SBRT procedure. Characterization of organ motion using 4DCT may not present true tumor motion excursion due to its low temporal resolution and patients' breathing irregularity. In treatment planning, tumor ITV could be significantly under/over-estimated by 4DCT. Different delivery techniques such as 3D-conformal, IMRT/VMAT, may introduce different degrees of uncertainties. The relative pros/cons of each motion management technique are usually not patient-specifically quantified, leading to uncertainty in finding the optimal technique for the patient. Other uncertainties include the choosing of planning CT, the determination of PTV and gating window, etc. At patient positioning, image guidance is prone to uncertainties due to technical limitations: CBCT may not present true ITV due to patient's irregular breathing. Rotational errors may not be fully corrected without six degree-of-freedom couch. At dose delivery, correlation between external motion and tumor motion is uncertain for respiratory-gated treatment. Tumor motion and size during treatment may be different from those measured at simulation, and may vary between fractions. For physics QAs, uncertainties in dose measurement devices and delivery devices could be substantial with inhomogeneity tissues. Quality control of lung SBRT requires accurate quantification of target motion by using the proper 4D-imaging technique and parameters based on patient's conditions, quantitative evaluation of different planning techniques, QA of treatment plan using 4D dosimeter and 4D phantom simulations, optimal patient positioning and motion monitoring during treatments.1. Provide an evidence-based systematic review of uncertainties during lung SBRT 2. Discuss the root causes of the uncertainties and corresponding quality control strategies 3. Present data-driven practical and effective solutions to minimize the uncertainties.

Authors
Yin, F; Benedict, S; Bradley, J; Cai, J; Wijesooriya, K
MLA Citation
Yin, F, Benedict, S, Bradley, J, Cai, J, and Wijesooriya, K. "WE-A-500-01: Quality Control of Lung SBRT: Minimizing Uncertainties From Simulation to Treatment." Medical physics 40.6Part28 (June 2013): 464-.
PMID
28519909
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part28
Publish Date
2013
Start Page
464
DOI
10.1118/1.4815490

MO-F-WAB-11: Investigation of CBCT-Based Patient Positioning Accuracy in Lung SBRT: Correlation with Breathing Irregularity.

To evaluate breathing irregularity induced error in CBCT-based patient positioning in lung SBRT and correlate the error with a measure of breathing variability.The 4D extended cardiac-torso (XCAT) digital phantom was used to generate 10-phase 4DCT and CBCT images using in-house developed simulation programs. Images were generated for various respiratory profiles (one regular sinusoidal and 10 irregular) and tumor sizes (1 cm, 2 cm, 3 cm). Maximum intensity projection (MIP) and average intensity projection (AIP) images were generated from 4DCT images. Image registrations between CBCT and AIP were performed for each respiratory profile and tumor size by four clinicians (two physicians and two physicists) based on target volume matching. Error of registration was determined as the difference between manual CBCT-to-AIP registration and known registration between the two. Breathing irregularities of the respiratory profiles were measured and correlated to errors of registration.Inter-observer variation of registration was 0.15 mm, 0.34 mm, and 0.69 mm, in the medial-lateral (ML), anterior-posterior (AP), and superior-inferior (SI) direction, respectively. For the regular profile, negligible errors of registration were found in all directions (median<0.5 mm). For the irregular profiles and all tumor sizes, small errors (median=0.5 mm) were found in the ML and AP directions, while non-trivial errors were seen in the SI direction (median (+/- SD): 2.10 (+/- 2.27) mm). No significant difference in mean error of registration was found for different tumor sizes (p>0.6). Maximum error of registration in the ML, AP, and SI direction was 1.2 mm, 2.6 mm, and 8.4 mm, respectively. Mild correlations (R2 range: 0.37 to 0.47) were observed between error of registration error and breathing irregularity for all tumor sizes.Irregular breathing can induce error in CBCT-based image registration in lung SBRT. This error increases as the breathing irregularity increases.

Authors
Turner, K; Zhang, Y; Vergalasova, I; Ren, L; Segars, P; Kelsey, C; Yoo, D; Yin, F; Cai, J
MLA Citation
Turner, K, Zhang, Y, Vergalasova, I, Ren, L, Segars, P, Kelsey, C, Yoo, D, Yin, F, and Cai, J. "MO-F-WAB-11: Investigation of CBCT-Based Patient Positioning Accuracy in Lung SBRT: Correlation with Breathing Irregularity." Medical physics 40.6Part24 (June 2013): 412-.
PMID
28518416
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part24
Publish Date
2013
Start Page
412
DOI
10.1118/1.4815300

WE-A-134-04: Comprehensive Evaluation of a Respiration-Phase-Matched Digital Tomosynthesis (DTS) Imaging Technique for Monitoring Moving Targets.

To develop a respiration-phase-matched DTS technique to monitor moving targets, and to evaluate its accuracy for various imaging parameters and anatomical characteristics Methods: Conventional methods, registering on-board DTS(OB-DTS, reconstructed from on-board projections) to reference DTS(R-DTS, reconstructed from DRRs of 3D-planning-CT), are inadequate to monitor moving targets. Our proposed technique registers OB-DTS to R-DTS reconstructed from DRRs generated by the same phase images of 4D-planning-CT as the corresponding on-board projections. To evaluate the improved accuracy of our technique, we performed thoracic phantom studies using (1)simulation with the 4D Digital Extended-cardiac-torso(XCAT) phantom, and (2)experiments with an anthropomorphic motion phantom. The studies were performed for various: respiratory-cycle(RC), scan angle and fraction of RC contained therein. Also, we assessed the accuracy of our technique relative to target size/location, and respiration changes from the planning-CT scan to on-board volume.In both simulation and experimental studies the respiration-phase-matched DTS technique is significantly more accurate in determining moving target positions. For 324 different scenarios simulated by XCAT, the respiration-phase-matched DTS technique localizes the 3D target position to within 1.07±0.57mm(mean±S.D.), as compared to (a)2.58±1.37mm and (b)7.37±4.18mm, for traditional DTS using 3D-planning-CT of (a)average-intensity-projection(AIP) and (b)free-breathing-CT(FB-CT). For the 60 scenarios evaluated through experimental study, the uncertainties corresponding to those above are 1.24±0.87mm, 2.42±1.80mm, and 5.77±6.45mm, respectively. For a given scan angle, the accuracy of respiration-phase-matched DTS technique is less dependent on RC and the fraction of RC included in the scan. Increasing scan angle improves its accuracy. Its accuracy is also minimally dependent on different tumor size/location combinations, or different respiratory cycle changes from planning-CT to on-board volume. Increasing the respiratory amplitude change will decrease its accuracy.The respiration-phase-matched DTS is more accurate and robust in determining moving target positions than traditional DTS. It has potential application in pre-treatment setup, post-treatment analysis and intra-fractional target verification. Research partially supported by grant from Varian Medical Systems.

Authors
Zhang, Y; Ren, L; Ling, C; Yin, F
MLA Citation
Zhang, Y, Ren, L, Ling, C, and Yin, F. "WE-A-134-04: Comprehensive Evaluation of a Respiration-Phase-Matched Digital Tomosynthesis (DTS) Imaging Technique for Monitoring Moving Targets." Medical physics 40.6Part28 (June 2013): 469-470.
PMID
28519947
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part28
Publish Date
2013
Start Page
469
End Page
470
DOI
10.1118/1.4815510

TU-G-141-03: An On-Board 4D-CBCT Reconstruction Technique Using Limited-Angle Projections Based On Motion Modeling and Free-Form Deformation (MM-FD).

To develop an on-board 4D-CBCT(OB-4D-CBCT) reconstruction technique using prior information and limited-angle projections for 4D inter/intra-fractional target verificationMethods: The OB-4D-CBCT at each phase is considered as a deformation of planning 4D-CT at one selected phase (prior image). The MM-FD technique solves the deformation field maps(DFMs) with a two-step approach: 1. MM: a principal component analysis-based method is applied to the planning 4D-CT to extract a motion model. Coarse estimation of DFMs are obtained by optimizing motion model parameters to meet data-fidelity constraint for limited-angle on-board projections. 2. FD: the coarse DFMs are further fine-tuned by free-form deformation based on data-fidelity constraint and deformation-energy minimization, using constrained-optimization algorithm ASD-POCS. OB-4D-CBCT is then reconstructed by deforming prior volume based on final DFMs. The 4D Digital Extended-cardiac-torso(XCAT) Phantom was used to evaluate MM-FD. A lung patient with 3-cm diameter lesion was simulated to have various anatomical and respirational changes from 4D-CT to OB-4D-CBCT including respiration amplitude change, lesion size change, lesion average-position change, and phase shift between lesion and body respiratory cycle. The lesions were contoured in both the reconstructed and 'ground-truth' OB-4D-CBCT for comparison. 3D volume percentage-difference (VD) and center-of-mass shifts(COMS) were calculated for evaluation. The MM-FD technique was compared with MM-only and FD-only techniques.For all patient scenarios, the mean original VD/COMS between prior volume and true OB-4D-CBCT were 137.65%/15.5mm. Using orthogonal-15-degree scan angle, the mean VD/COMS between reconstructed and true OB-4D-CBCT for MM-only, FD-only and MM-FD techniques were 64.67%/4.9mm, 98.80%/12.1mm and 20.90%/1.3mm, respectively. For orthogonal-30-degree scan angle, the corresponding results were 63.87%/4.9mm, 79.92%/9.9mm and 15.23%/0.5mm. For single-view 30-and 60-degree projections, the mean VD/COMS for MM-FD technique were 32.67%/2.9mm and 19.67%/1.1mm, respectively.The MM-FD technique substantially improves the reconstruction accuracy for OB-4D-CBCT using limited-angle projections. It can potentially improve the inter/intra-fractional 4D-localization accuracy for lung SBRT. Research partially supported by grant from Varian Medical Systems.

Authors
Zhang, Y; Segars, P; Yin, F; Ren, L
MLA Citation
Zhang, Y, Segars, P, Yin, F, and Ren, L. "TU-G-141-03: An On-Board 4D-CBCT Reconstruction Technique Using Limited-Angle Projections Based On Motion Modeling and Free-Form Deformation (MM-FD)." Medical physics 40.6Part27 (June 2013): 456-.
PMID
28518822
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part27
Publish Date
2013
Start Page
456
DOI
10.1118/1.4815463

SU-E-T-602: Dynamic Electron Arc Radiotherapy (DEAR): A Planning Study.

Electron beam therapy is under-utilized in radiation treatment of cancer and has remained practically unchanged for decades. We propose a new technique, Dynamic Electron Arc Radiotherapy (DEAR) with synchronized couch motion. In DEAR, gantry rotation, dose rate, and intensities are modulated to create desirable dose distributions free of hot and/or cold spots, with high homogeneity, and narrow penumbra. This study demonstrates the potential of DEAR in improving dose distributions.Dose distributions for single-field and two-field were compared to DEAR with equal and optimized beam weights on a 32 cm diameter cylindrical phantom. Plans were designed to irradiate equivalent field size on the phantom surface, with the target dimension extending from 315° -45° in radial angle and target depth at 1 cm (6 MeV) or 2 cm (9 MeV). Penumbra (20-80%), dose homogeneity, and dose area histogram (DAH) were evaluated at target depths. Plans were calculated with the eMC algorithm in Eclipse v10.In-plane (longitudinal direction) penumbra was comparable across all plans as expected. Cross-plane (along curved surface) penumbra was 5.0, 1.5, and 2.0 cm (6 MeV) and 5.6, 1.7, and 2.1 (9 MeV), for single-field, two-field, and DEAR, respectively. While the two-field penumbra was better, it exhibited a hot spot 60% higher than the target mean at the beam junction covering approximately 20% of the target. DEAR plans displayed homogenous dose distributions with variations of less than ±1.5%. DAH of the single-field failed to achieve optimal coverage, while the two-field displayed a high-dose tail (>100%). 90% of the target receives at least 95% (two-field) and 88% (DEAR) of the target dose.Preliminary findings show that DEAR can produce homogenous dose distributions over large and curved targets without hot and/or cold spots while maintaining narrow penumbra. Future work includes planning for various target shapes and desired dose distributions.

Authors
Rodrigues, A; Yin, F; Wu, Q
MLA Citation
Rodrigues, A, Yin, F, and Wu, Q. "SU-E-T-602: Dynamic Electron Arc Radiotherapy (DEAR): A Planning Study." Medical physics 40.6Part20 (June 2013): 344-.
PMID
28519099
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part20
Publish Date
2013
Start Page
344
DOI
10.1118/1.4815030

TH-C-137-11: Dose-Guided Automatic IMRT Planning: A Feasibility Study.

To develop and evaluate an automatic planning technique for prostate cancer utilizing prior expert plan's dose as guidance.A plan atlas was created using 10 expert prostate IMRT plans covering a variety of typical anatomical configurations. The target includes both prostate and seminal vesicle. Additional 9 patients (query cases) were used to test the automatic planning, which started by matching the query case to the atlas based on the overall PTV-OAR anatomical configuration. The anatomy of the matched atlas case is then linked to the query case via deformable registration in MIM Maestro™, which provides fine local-regional matching. Following the same anatomical deformation, the expert dose in atlas is warped onto the query case, creating the goal dose conforming the query case's target. DVH objectives were sampled from the goal dose to guide automatic IMRT treatment planning in Eclipse™ for the query case. Dosimetry comparison between dose-guided automatic plans (DAPs) and clinical plans for query cases are reported.Generating goal dose is highly efficient with customized workflows in MIM™. The deformation registration provides a realistic goal dose for the query cases in terms of dose fall off at the PTV-OAR junctions and PTV conformity. The automatic planning takes ∼2.5 min (∼70 iterations) without human intervention. Compared to clinical plans, DAPs improved the PTV conformity index from 1.031±0.044 for expert plans to 1.005±0.019 (p=0.04). Other dosimetric parameters are similar between DAP and clinical plans (p>0.1): homogeneity indices are 0.073±0.010 and 0.079±0.015; Bladder-gEUDs are 3917±352 cGy and 3934±354 cGy; Rectum-gEUDs are 3923±256 cGy and 3932±323 cGy, respectively.Dose-guided automatic treatment planning is feasible and efficient. Atlas-based patient-specific DVH objectives can effectively guide the optimizer to achieve similar or better plan quality compared to clinical plans.(The authors thank Adam Neff from MIM Software Inc. for technical supports.) The study is partially supported by NIH grant and a Varian master research grant.

Authors
Sheng, Y; Li, T; Yuan, L; Yin, F; Wu, Q
MLA Citation
Sheng, Y, Li, T, Yuan, L, Yin, F, and Wu, Q. "TH-C-137-11: Dose-Guided Automatic IMRT Planning: A Feasibility Study." Medical physics 40.6Part32 (June 2013): 535-.
PMID
28517871
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part32
Publish Date
2013
Start Page
535
DOI
10.1118/1.4815754

SU-D-500-06: On-Board Robotic Multi-Pinhole SPECT System for Prone Breast Imaging.

To investigate a novel Single Photon Emission Computed Tomography (SPECT) system for on-board molecular and functional imaging in partial breast radiation therapy of prone patients.Computer-simulation studies were performed for on-board robotic 49-pinhole and reference conventional clinical parallel-hole collimated SPECT systems. A female XCAT phantom was simulated in prone position with nine tumors of 10mm diameter in the left breast. The simulations included two commercial prone breast boards, 24 and 7 cm thick. Four-minute trajectories of the 49-pinhole and parallel-hole systems were designed to image a 7cm-diameter target region encompassing the tumors. Noisy Poisson-distributed projection data were drawn from these simulated projections, and SPECT images were reconstructed by OSEM with up to 10 iterations. Images were evaluated by visual inspection, profiles, and root mean squared error (RMSE). Results were correlated with trajectory radii of rotation. Commercial CAD programs were utilized to evaluate the feasibility of robot and detector trajectories about the patient, treatment table, prone breast board and LINAC gantry.With 4-minute scans of the proposed 49-pinhole SPECT system, using the thinner prone breast board, almost all of the 9 tumors were well visualized above background. Few if any of the tumors were apparent in the parallel-hole images. With the thinner board, lowest RMSE values, across all iterations, were 0.206 for 49-pinhole and 0.251 for parallel-hole. For the thicker board, these RMSE results were 0.234 and 0.260 respectively. These results correspond to smaller radii of rotation with the thinner board. CAD simulations indicate feasibility in terms of geometrical considerations.The proposed on-board robotic multi-pinhole SPECT approach shows promising results for targeted molecular and functional imaging of the breast as patients are in prone position for radiation therapy, especially with breast boards that allow closer detector proximity. PHS/NIH/NCI grant R21-CA156390-01A1.

Authors
Yan, S; Bowsher, J; Yoo, S; Yin, F
MLA Citation
Yan, S, Bowsher, J, Yoo, S, and Yin, F. "SU-D-500-06: On-Board Robotic Multi-Pinhole SPECT System for Prone Breast Imaging." Medical physics 40.6Part3 (June 2013): 106-.
PMID
28519561
Source
epmc
Published In
Medical physics
Volume
40
Issue
6Part3
Publish Date
2013
Start Page
106
DOI
10.1118/1.4814023

TH-A-WAB-04: Respiratory Sorted Imaging Using Region-Of-Interest Robotic Multi-Pinhole SPECT System

Authors
Yan, S; Bowsher, J; Yin, F
MLA Citation
Yan, S, Bowsher, J, and Yin, F. "TH-A-WAB-04: Respiratory Sorted Imaging Using Region-Of-Interest Robotic Multi-Pinhole SPECT System." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part31
Publish Date
2013
Start Page
520
End Page
520
DOI
10.1118/1.4815698

SU-E-T-474: Adaptive Stereotactic Body Radiation Therapy (SBRT) Planning for Lung Cancer: Can We Predict Who Will Benefit?

Authors
Qin, Y; Kelsey, C; Yoo, D; Yin, F; Cai, J
MLA Citation
Qin, Y, Kelsey, C, Yoo, D, Yin, F, and Cai, J. "SU-E-T-474: Adaptive Stereotactic Body Radiation Therapy (SBRT) Planning for Lung Cancer: Can We Predict Who Will Benefit?." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part18
Publish Date
2013
Start Page
314
End Page
314
DOI
10.1118/1.4814907

TU-C-141-08: Evaluate Deformable Image Registration for the Lungs Using Hyperpolarized Gas Tagging MRI

Authors
Liu, Y; Miller, W; Yin, F; Cai, J
MLA Citation
Liu, Y, Miller, W, Yin, F, and Cai, J. "TU-C-141-08: Evaluate Deformable Image Registration for the Lungs Using Hyperpolarized Gas Tagging MRI." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part26
Publish Date
2013
Start Page
435
End Page
435
DOI
10.1118/1.4815385

SU-E-J-150: Investigation of Feasibility of Concurrent Orthogonal KV and MV X-Ray Imaging for Tagrget Tracking During Dose Delivery for Stereotactic Body Radiotherapy (SBRT): A Pilot Phantom Study

Authors
Chang, Z; Yan, H; Yin, F
MLA Citation
Chang, Z, Yan, H, and Yin, F. "SU-E-J-150: Investigation of Feasibility of Concurrent Orthogonal KV and MV X-Ray Imaging for Tagrget Tracking During Dose Delivery for Stereotactic Body Radiotherapy (SBRT): A Pilot Phantom Study." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part9
Publish Date
2013
Start Page
185
End Page
185
DOI
10.1118/1.4814362

SU-E-CAMPUS-J-04: Evaluating Radiation-Induced Changes with Diffusion Weighted MRI and Dynamic Contrast Enhanced MRI in Patients with Early Stage Breast Cancer Treated with Stereotactic Body Radiotherapy: Initial Results

Authors
Chang, Z; Yin, F; Yoo, S; Horton, J
MLA Citation
Chang, Z, Yin, F, Yoo, S, and Horton, J. "SU-E-CAMPUS-J-04: Evaluating Radiation-Induced Changes with Diffusion Weighted MRI and Dynamic Contrast Enhanced MRI in Patients with Early Stage Breast Cancer Treated with Stereotactic Body Radiotherapy: Initial Results." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part22
Publish Date
2013
Start Page
378
End Page
379
DOI
10.1118/1.4815176

SU-E-T-707: Evaluation of the Quality of Organs-At-Risk Dose Sparing in Anorectal and Prostate IMRT Plans

Authors
Lu, S; Yuan, L; Yin, F; Wu, QJ
MLA Citation
Lu, S, Yuan, L, Yin, F, and Wu, QJ. "SU-E-T-707: Evaluation of the Quality of Organs-At-Risk Dose Sparing in Anorectal and Prostate IMRT Plans." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part22
Publish Date
2013
Start Page
369
End Page
369
DOI
10.1118/1.4815134

TH-C-137-08: Dosimetric Quality of An Automatic IMRT Planning Method for Head and Neck Cancer Cases

Authors
Yuan, L; Pang, T; Ge, Y; Li, T; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Pang, T, Ge, Y, Li, T, Yin, F, and Wu, QJ. "TH-C-137-08: Dosimetric Quality of An Automatic IMRT Planning Method for Head and Neck Cancer Cases." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part32
Publish Date
2013
Start Page
534
End Page
534
DOI
10.1118/1.4815751

SU-E-CAMPUS-T-05: Quality Evaluation of An Automatic VMAT Planning Method for Head and Neck Cancer Cases

Authors
Yuan, L; Pang, T; Ge, Y; Li, T; Jiang, Y; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Pang, T, Ge, Y, Li, T, Jiang, Y, Yin, F, and Wu, QJ. "SU-E-CAMPUS-T-05: Quality Evaluation of An Automatic VMAT Planning Method for Head and Neck Cancer Cases." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part22
Publish Date
2013
Start Page
380
End Page
380
DOI
10.1118/1.4815183

SU-E-J-91: Developing Platform for Online Registration Using Digital Tomosynthesis

Authors
Yan, H; Yin, F
MLA Citation
Yan, H, and Yin, F. "SU-E-J-91: Developing Platform for Online Registration Using Digital Tomosynthesis." June 2013.
Source
crossref
Published In
Medical physics
Volume
40
Issue
6Part8
Publish Date
2013
Start Page
171
End Page
171
DOI
10.1118/1.4814303

Spiral computed tomography phase-space source model in the BEAMnrc/EGSnrc Monte Carlo system: implementation and validation.

Currently, the BEAMnrc/EGSnrc Monte Carlo (MC) system does not provide a spiral CT source model for the simulation of spiral CT scanning. We developed and validated a spiral CT phase-space source model in the BEAMnrc/EGSnrc system. The spiral phase-space source model was implemented in the DOSXYZnrc user code of the BEAMnrc/EGSnrc system by analyzing the geometry of spiral CT scan-scan range, initial angle, rotational direction, pitch, slice thickness, etc. Table movement was simulated by changing the coordinates of the isocenter as a function of beam angles. Some parameters such as pitch, slice thickness and translation per rotation were also incorporated into the model to make the new phase-space source model, designed specifically for spiral CT scan simulations. The source model was hard-coded by modifying the 'ISource = 8: Phase-Space Source Incident from Multiple Directions' in the srcxyznrc.mortran and dosxyznrc.mortran files in the DOSXYZnrc user code. In order to verify the implementation, spiral CT scans were simulated in a CT dose index phantom using the validated x-ray tube model of a commercial CT simulator for both the original multi-direction source (ISOURCE = 8) and the new phase-space source model in the DOSXYZnrc system. Then the acquired 2D and 3D dose distributions were analyzed with respect to the input parameters for various pitch values. In addition, surface-dose profiles were also measured for a patient CT scan protocol using radiochromic film and were compared with the MC simulations. The new phase-space source model was found to simulate the spiral CT scanning in a single simulation run accurately. It also produced the equivalent dose distribution of the ISOURCE = 8 model for the same CT scan parameters. The MC-simulated surface profiles were well matched to the film measurement overall within 10%. The new spiral CT phase-space source model was implemented in the BEAMnrc/EGSnrc system. This work will be beneficial in estimating the spiral CT scan dose in the BEAMnrc/EGSnrc system.

Authors
Kim, S; Yoshizumi, TT; Yin, F-F; Chetty, IJ
MLA Citation
Kim, S, Yoshizumi, TT, Yin, F-F, and Chetty, IJ. "Spiral computed tomography phase-space source model in the BEAMnrc/EGSnrc Monte Carlo system: implementation and validation." Phys Med Biol 58.8 (April 21, 2013): 2609-2624.
PMID
23552614
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
58
Issue
8
Publish Date
2013
Start Page
2609
End Page
2624
DOI
10.1088/0031-9155/58/8/2609

Improving Tumor-to-Tissue CNR of 4D-MRI Using Deformable Image Registration.

Authors
Cai, J; Chang, Z; Czito, B; Yin, F
MLA Citation
Cai, J, Chang, Z, Czito, B, and Yin, F. "Improving Tumor-to-Tissue CNR of 4D-MRI Using Deformable Image Registration." Practical radiation oncology 3.2 Suppl 1 (April 2013): S8-S9.
PMID
24674569
Source
epmc
Published In
Practical Radiation Oncology
Volume
3
Issue
2 Suppl 1
Publish Date
2013
Start Page
S8
End Page
S9
DOI
10.1016/j.prro.2013.01.027

Phase/Amplitude-matched Digital Tomosynthesis (DTS) Imaging for Moving Target Localization.

Authors
Ren, L; Zhang, Y; Yin, F
MLA Citation
Ren, L, Zhang, Y, and Yin, F. "Phase/Amplitude-matched Digital Tomosynthesis (DTS) Imaging for Moving Target Localization." Practical radiation oncology 3.2 Suppl 1 (April 2013): S20-S21.
PMID
24674507
Source
epmc
Published In
Practical Radiation Oncology
Volume
3
Issue
2 Suppl 1
Publish Date
2013
Start Page
S20
End Page
S21
DOI
10.1016/j.prro.2013.01.070

Quantification and minimization of uncertainties of internal target volume for stereotactic body radiation therapy of lung cancer.

PURPOSE: To quantify uncertainties in delineating an internal target volume (ITV) and to understand how these uncertainties may be individually minimized for stereotactic body radiation therapy (SBRT) of early stage non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: Twenty patients with NSCLC who were undergoing SBRT were imaged with free-breathing 3-dimensional computed tomography (3DCT) and 10-phase 4-dimensional CT (4DCT) for delineating gross tumor volume (GTV)(3D) and ITV(10Phase) (ITV3). The maximum intensity projection (MIP) CT was also calculated from 10-phase 4DCT for contouring ITV(MIP) (ITV1). Then, ITV(COMB) (ITV2), ITV(10Phase+GTV3D) (ITV4), and ITV(10Phase+ITVCOMB) (ITV5) were generated by combining ITV(MIP) and GTV(3D), ITV(10phase) and GTV(3D), and ITV(10phase) and ITV(COMB), respectively. All 6 volumes (GTV(3D) and ITV1 to ITV5) were delineated in the same lung window by the same radiation oncologist. The percentage of volume difference (PVD) between any 2 different volumes was determined and was correlated to effective tumor diameter (ETD), tumor motion ranges, R(3D), and the amplitude variability of the recorded breathing signal (v) to assess their volume variations. RESULTS: The mean (range) tumor motion (R(SI), R(AP), R(ML), and R(3D)) and breathing variability (v) were 7.6 mm (2-18 mm), 4.0 mm (2-8 mm), 3.3 mm (0-7.5 mm), 9.9 mm (4.1-18.7 mm), and 0.17 (0.07-0.37), respectively. The trend of volume variation was GTV(3D)

Authors
Ge, H; Cai, J; Kelsey, CR; Yin, F-F
MLA Citation
Ge, H, Cai, J, Kelsey, CR, and Yin, F-F. "Quantification and minimization of uncertainties of internal target volume for stereotactic body radiation therapy of lung cancer." Int J Radiat Oncol Biol Phys 85.2 (February 1, 2013): 438-443.
PMID
22687196
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
85
Issue
2
Publish Date
2013
Start Page
438
End Page
443
DOI
10.1016/j.ijrobp.2012.04.032

Investigation of sliced body volume (SBV) as respiratory surrogate.

The purpose of this study was to evaluate the sliced body volume (SBV) as a respiratory surrogate by comparing with the real-time position management (RPM) in phantom and patient cases. Using the SBV surrogate, breathing signals were extracted from unsorted 4D CT images of a motion phantom and 31 cancer patients (17 lung cancers, 14 abdominal cancers) and were compared to those clinically acquired using the RPM system. Correlation coefficient (R), phase difference (D), and absolute phase difference (D(A)) between the SBV-derived breathing signal and the RPM signal were calculated. 4D CT reconstructed based on the SBV surrogate (4D CT(SBV)) were compared to those clinically generated based on RPM (4D CT(RPM)). Image quality of the 4D CT were scored (S(SBV) and S(RPM), respectively) from 1 to 5 (1 is the best) by experienced evaluators. The comparisons were performed for all patients, and for the lung cancer patients and the abdominal cancer patients separately. RPM box position (P), breathing period (T), amplitude (A), period variability (V(T)), amplitude variability (V(A)), and space-dependent phase shift (F) were determined and correlated to S(SBV). The phantom study showed excellent match between the SBV-derived breathing signal and the RPM signal (R = 0.99, D= -3.0%, D(A) = 4.5%). In the patient study, the mean (± standard deviation (SD)) R, D, D(A), T, V(T), A, V(A), and F were 0.92 (± 0.05), -3.3% (± 7.5%), 11.4% (± 4.6%), 3.6 (± 0.8) s, 0.19 (± 0.10), 6.6 (± 2.8) mm, 0.20 (± 0.08), and 0.40 (± 0.18) s, respectively. Significant differences in R and D(A) (p = 0.04 and 0.001, respectively) were found between the lung cancer patients and the abdominal cancer patients. 4D CT(RPM) slightly outperformed 4D CT(SBV): the mean (± SD) S(RPM) and S(SBV) were 2.6 (± 0.6) and 2.9 (± 0.8), respectively, for all patients, 2.5 (± 0.6) and 3.1 (± 0.8), respectively, for the lung cancer patients, and 2.6 (± 0.7) and 2.8 (± 0.9), respectively, for the abdominal cancer patients. The difference between S(RPM) and S(SBV) was insignificant for the abdominal patients (p = 0.59). F correlated moderately with S(SBV) (r = 0.72). The correlation between SBV-derived breathing signal and RPM signal varied between patients and was significantly better in the abdomen than in the thorax. Space-dependent phase shift is a limiting factor of the accuracy of the SBV surrogate.

Authors
Cai, J; Chang, Z; O'Daniel, J; Yoo, S; Ge, H; Kelsey, C; Yin, F-F
MLA Citation
Cai, J, Chang, Z, O'Daniel, J, Yoo, S, Ge, H, Kelsey, C, and Yin, F-F. "Investigation of sliced body volume (SBV) as respiratory surrogate. (Published online)" J Appl Clin Med Phys 14.1 (January 7, 2013): 3987-.
PMID
23318383
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
14
Issue
1
Publish Date
2013
Start Page
3987

A line-source method for aligning on-board and other pinhole SPECT systems

Purpose: In order to achieve functional and molecular imaging as patients are in position for radiation therapy, a robotic multipinhole SPECT system is being developed. Alignment of the SPECT system - to the linear accelerator (LINAC) coordinate frame and to the coordinate frames of other on-board imaging systems such as cone-beam CT (CBCT) - is essential for target localization and image reconstruction. An alignment method that utilizes line sources and one pinhole projection is proposed and investigated to achieve this goal. Potentially, this method could also be applied to the calibration of the other pinhole SPECT systems. Methods: An alignment model consisting of multiple alignment parameters was developed which maps line sources in three-dimensional (3D) space to their two-dimensional (2D) projections on the SPECT detector. In a computer-simulation study, 3D coordinates of line-sources were defined in a reference room coordinate frame, such as the LINAC coordinate frame. Corresponding 2D line-source projections were generated by computer simulation that included SPECT blurring and noise effects. The Radon transform was utilized to detect angles (α) and offsets (ρ) of the line-source projections. Alignment parameters were then estimated by a nonlinear least squares method, based on the α and ρ values and the alignment model. Alignment performance was evaluated as a function of number of line sources, Radon transform accuracy, finite line-source width, intrinsic camera resolution, Poisson noise, and acquisition geometry. Experimental evaluations were performed using a physical line-source phantom and a pinhole-collimated gamma camera attached to a robot. Results: In computer-simulation studies, when there was no error in determining angles (α) and offsets (ρ) of the measured projections, six alignment parameters (three translational and three rotational) were estimated perfectly using three line sources. When angles (α) and offsets (ρ) were provided by the Radon transform, estimation accuracy was reduced. The estimation error was associated with rounding errors of Radon transform, finite line-source width, Poisson noise, number of line sources, intrinsic camera resolution, and detector acquisition geometry. Statistically, the estimation accuracy was significantly improved by using four line sources rather than three and by thinner line-source projections (obtained by better intrinsic detector resolution). With five line sources, median errors were 0.2 mm for the detector translations, 0.7 mm for the detector radius of rotation, and less than 0.5°for detector rotation, tilt, and twist. In experimental evaluations, average errors relative to a different, independent registration technique were about 1.8 mm for detector translations, 1.1 mm for the detector radius of rotation (ROR), 0.5°and 0.4°for detector rotation and tilt, respectively, and 1.2°for detector twist. Conclusions: Alignment parameters can be estimated using one pinhole projection of line sources. Alignment errors are largely associated with limited accuracy of the Radon transform in determining angles (α) and offsets (ρ) of the line-source projections. This alignment method may be important for multipinhole SPECT, where relative pinhole alignment may vary during rotation. For pinhole and multipinhole SPECT imaging on-board radiation therapy machines, the method could provide alignment of SPECT coordinates with those of CBCT and the LINAC. © 2013 American Association of Physicists in Medicine.

Authors
Yan, S; Bowsher, J; Yin, FF
MLA Citation
Yan, S, Bowsher, J, and Yin, FF. "A line-source method for aligning on-board and other pinhole SPECT systems." Medical Physics 40.12 (January 1, 2013).
PMID
24320537
Source
scopus
Published In
Medical physics
Volume
40
Issue
12
Publish Date
2013
DOI
10.1118/1.4828776

Generation of virtual monochromatic CBCT from dual kV/MV beam projections

Purpose: To develop a novel on-board imaging technique which allows generation of virtual monochromatic (VM) cone-beam CT (CBCT) with a selected energy from combined kilovoltage (kV)/megavoltage (MV) beam projections. Methods: With the current orthogonal kV/MV imaging hardware equipped in modern linear accelerators, both MV projections (from gantry angle of 0°-100°) and kV projections (90°-200°) were acquired as gantry rotated a total of 110°. A selected range of overlap projections between 90°to 100°were then decomposed into two material projections using experimentally determined parameters from orthogonally stacked aluminum and acrylic step-wedges. Given attenuation coefficients of aluminum and acrylic at a predetermined energy, one set of VM projections could be synthesized from two corresponding sets of decomposed projections. Two linear functions were generated using projection information at overlap angles to convert kV and MV projections at nonoverlap angles to approximate VM projections for CBCT reconstruction. The contrast-to-noise ratios (CNRs) were calculated for different inserts in VM CBCTs of a CatPhan phantom with various selected energies and compared with those in kV and MV CBCTs. The effect of overlap projection number on CNR was evaluated. Additionally, the effect of beam orientation was studied by scanning the CatPhan sandwiched with two 5 cm solid-water phantoms on both lateral sides and an electronic density phantom with two metal bolt inserts. Results: Proper selection of VM energy 30 and 40 keV for low-density polyethylene (LDPE), polymethylpentene, 2 MeV for Delrinprovided comparable or even better CNR results as compared with kV or MV CBCT. An increased number of overlap kV and MV projection demonstrated only marginal improvements of CNR for different inserts (with the exception of LDPE) and therefore one projection overlap was found to be sufficient for the CatPhan study. It was also evident that the optimal CBCT image quality was achieved when MV beams penetrated through the heavy attenuation direction of the object. Conclusions: A novel technique was developed to generate VM CBCTs from kV/MV projections. This technique has the potential to improve CNR at selected VM energies and to suppress artifacts at appropriate beam orientations. © 2013 American Association of Physicists in Medicine.

Authors
Li, H; Liu, B; Yin, FF
MLA Citation
Li, H, Liu, B, and Yin, FF. "Generation of virtual monochromatic CBCT from dual kV/MV beam projections." Medical Physics 40.12 (January 1, 2013).
PMID
24320521
Source
scopus
Published In
Medical physics
Volume
40
Issue
12
Publish Date
2013
DOI
10.1118/1.4824324

Implementation of remote 3-dimensional image guided radiation therapy quality assurance for radiation therapy oncology group clinical trials.

PURPOSE: To report the process and initial experience of remote credentialing of three-dimensional (3D) image guided radiation therapy (IGRT) as part of the quality assurance (QA) of submitted data for Radiation Therapy Oncology Group (RTOG) clinical trials; and to identify major issues resulting from this process and analyze the review results on patient positioning shifts. METHODS AND MATERIALS: Image guided radiation therapy datasets including in-room positioning CT scans and daily shifts applied were submitted through the Image Guided Therapy QA Center from institutions for the IGRT credentialing process, as required by various RTOG trials. A centralized virtual environment is established at the RTOG Core Laboratory, containing analysis tools and database infrastructure for remote review by the Physics Principal Investigators of each protocol. The appropriateness of IGRT technique and volumetric image registration accuracy were evaluated. Registration accuracy was verified by repeat registration with a third-party registration software system. With the accumulated review results, registration differences between those obtained by the Physics Principal Investigators and from the institutions were analyzed for different imaging sites, shift directions, and imaging modalities. RESULTS: The remote review process was successfully carried out for 87 3D cases (out of 137 total cases, including 2-dimensional and 3D) during 2010. Frequent errors in submitted IGRT data and challenges in the review of image registration for some special cases were identified. Workarounds for these issues were developed. The average differences of registration results between reviewers and institutions ranged between 2 mm and 3 mm. Large discrepancies in the superior-inferior direction were found for megavoltage CT cases, owing to low spatial resolution in this direction for most megavoltage CT cases. CONCLUSION: This first experience indicated that remote review for 3D IGRT as part of QA for RTOG clinical trials is feasible and effective. The magnitude of registration discrepancy between institution and reviewer was presented, and the major issues were investigated to further improve this remote evaluation process.

Authors
Cui, Y; Galvin, JM; Parker, W; Breen, S; Yin, F-F; Cai, J; Papiez, LS; Li, XA; Bednarz, G; Chen, W; Xiao, Y
MLA Citation
Cui, Y, Galvin, JM, Parker, W, Breen, S, Yin, F-F, Cai, J, Papiez, LS, Li, XA, Bednarz, G, Chen, W, and Xiao, Y. "Implementation of remote 3-dimensional image guided radiation therapy quality assurance for radiation therapy oncology group clinical trials." Int J Radiat Oncol Biol Phys 85.1 (January 1, 2013): 271-277.
PMID
22541964
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
85
Issue
1
Publish Date
2013
Start Page
271
End Page
277
DOI
10.1016/j.ijrobp.2012.03.002

Investigation of sliced body volume (SBV) as respiratory surrogate

Authors
Cai, J; Chang, Z; O'Daniel, J; Yoo, S; Ge, H; Kelsey, C; Yin, F-F
MLA Citation
Cai, J, Chang, Z, O'Daniel, J, Yoo, S, Ge, H, Kelsey, C, and Yin, F-F. "Investigation of sliced body volume (SBV) as respiratory surrogate." JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 14.1 (2013): 71-80.
Source
wos-lite
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
14
Issue
1
Publish Date
2013
Start Page
71
End Page
80

Implementing and integrating a clinically driven electronic medical record for radiation oncology in a large medical enterprise.

PURPOSE/OBJECTIVE: While our department is heavily invested in computer-based treatment planning, we historically relied on paper-based charts for management of Radiation Oncology patients. In early 2009, we initiated the process of conversion to an electronic medical record (EMR) eliminating the need for paper charts. Key goals included the ability to readily access information wherever and whenever needed, without compromising safety, treatment quality, confidentiality, or productivity. METHODOLOGY: In February, 2009, we formed a multi-disciplinary team of Radiation Oncology physicians, nurses, therapists, administrators, physicists/dosimetrists, and information technology (IT) specialists, along with staff from the Duke Health System IT department. The team identified all existing processes and associated information/reports, established the framework for the EMR system and generated, tested and implemented specific EMR processes. RESULTS: Two broad classes of information were identified: information which must be readily accessed by anyone in the health system versus that used solely within the Radiation Oncology department. Examples of the former are consultation reports, weekly treatment check notes, and treatment summaries; the latter includes treatment plans, daily therapy records, and quality assurance reports. To manage the former, we utilized the enterprise-wide system, which required an intensive effort to design and implement procedures to export information from Radiation Oncology into that system. To manage "Radiation Oncology" data, we used our existing system (ARIA, Varian Medical Systems.) The ability to access both systems simultaneously from a single workstation (WS) was essential, requiring new WS and modified software. As of January, 2010, all new treatments were managed solely with an EMR. We find that an EMR makes information more widely accessible and does not compromise patient safety, treatment quality, or confidentiality. However, compared to paper charts, time required by clinicians to access/enter patient information has substantially increased. While productivity is improving with experience, substantial growth will require better integration of the system components, decreased access times, and improved user interfaces. $127K was spent on new hardware and software; elimination of paper yields projected savings of $21K/year. One year after conversion to an EMR, more than 90% of department staff favored the EMR over the previous paper charts. CONCLUSION: Successful implementation of a Radiation Oncology EMR required not only the effort and commitment of all functions of the department, but support from senior health system management, corporate IT, and vendors. Realization of the full benefits of an EMR will require experience, faster/better integrated software, and continual improvement in underlying clinical processes.

Authors
Kirkpatrick, JP; Light, KL; Walker, RM; Georgas, DL; Antoine, PA; Clough, RW; Cozart, HB; Yin, F-F; Yoo, S; Willett, CG
MLA Citation
Kirkpatrick, JP, Light, KL, Walker, RM, Georgas, DL, Antoine, PA, Clough, RW, Cozart, HB, Yin, F-F, Yoo, S, and Willett, CG. "Implementing and integrating a clinically driven electronic medical record for radiation oncology in a large medical enterprise. (Published online)" Front Oncol 3 (2013): 69-.
PMID
23616946
Source
pubmed
Published In
Frontiers in Oncology
Volume
3
Publish Date
2013
Start Page
69
DOI
10.3389/fonc.2013.00069

A dual cone-beam CT system for image guided radiotherapy: Initial performance characterization

Purpose: The purpose of this study is to evaluate the performance of a recently developed benchtop dual cone-beam computed tomography (CBCT) system with two orthogonally placed tube/detector sets. Methods: The benchtop dual CBCT system consists of two orthogonally placed 40 × 30 cm flat-panel detectors and two conventional x-ray tubes with two individual high-voltage generators sharing the same rotational axis. The x-ray source to detector distance is 150 cm and x-ray source to rotational axis distance is 100 cm for both subsystems. The objects are scanned through 200° of rotation. The dual CBCT system utilized 110° of projection data from one detector and 90° from the other while the two individual single CBCTs utilized 200° data from each detector. The system performance was characterized in terms of uniformity, contrast, spatial resolution, noise power spectrum, and CT number linearity. The uniformities, within the axial slice and along the longitudinal direction, and noise power spectrum were assessed by scanning a water bucket; the contrast and CT number linearity were measured using the Catphan phantom; and the spatial resolution was evaluated using a tungsten wire phantom. A skull phantom and a ham were also scanned to provide qualitative evaluation of high- and low-contrast resolution. Each measurement was compared between dual and single CBCT systems. Results: Compared to single CBCT, the dual CBCT presented: (1) a decrease in uniformity by 1.9% in axial view and 1.1% in the longitudinal view, as averaged for four energies (80, 100, 125, and 150 kVp); (2) comparable or slightly better contrast (0∼25 HU) for low-contrast objects and comparable contrast for high-contrast objects; (3) comparable spatial resolution; (4) comparable CT number linearity with R2 ≥ 0.99 for all four tested energies; (5) lower noise power spectrum in magnitude. Dual CBCT images of the skull phantom and the ham demonstrated both high-contrast resolution and good soft-tissue contrast. Conclusions: The performance of a benchtop dual CBCT imaging system has been characterized and is comparable to that of a single CBCT. © 2013 American Association of Physicists in Medicine.

Authors
Li, H; Giles, W; Bowsher, J; Yin, F-F
MLA Citation
Li, H, Giles, W, Bowsher, J, and Yin, F-F. "A dual cone-beam CT system for image guided radiotherapy: Initial performance characterization." Medical Physics 40.2 (2013).
PMID
23387760
Source
scival
Published In
Medical physics
Volume
40
Issue
2
Publish Date
2013
DOI
10.1118/1.4788654

Quantification and minimization of uncertainties of internal target volume for stereotactic body radiation therapy of lung cancer

Purpose: To quantify uncertainties in delineating an internal target volume (ITV) and to understand how these uncertainties may be individually minimized for stereotactic body radiation therapy (SBRT) of early stage non-small cell lung cancer (NSCLC). Methods and Materials: Twenty patients with NSCLC who were undergoing SBRT were imaged with free-breathing 3-dimensional computed tomography (3DCT) and 10-phase 4-dimensional CT (4DCT) for delineating gross tumor volume (GTV)3D and ITV10Phase (ITV3). The maximum intensity projection (MIP) CT was also calculated from 10-phase 4DCT for contouring ITVMIP (ITV1). Then, ITVCOMB (ITV2), ITV 10Phase+GTV3D (ITV4), and ITV10Phase+ITVCOMB (ITV5) were generated by combining ITVMIP and GTV3D, ITV 10phase and GTV3D, and ITV10phase and ITV COMB, respectively. All 6 volumes (GTV3D and ITV1 to ITV5) were delineated in the same lung window by the same radiation oncologist. The percentage of volume difference (PVD) between any 2 different volumes was determined and was correlated to effective tumor diameter (ETD), tumor motion ranges, R3D, and the amplitude variability of the recorded breathing signal (v) to assess their volume variations. Results: The mean (range) tumor motion (RSI, RAP, RML, and R3D) and breathing variability (v) were 7.6 mm (2-18 mm), 4.0 mm (2-8 mm), 3.3 mm (0-7.5 mm), 9.9 mm (4.1-18.7 mm), and 0.17 (0.07-0.37), respectively. The trend of volume variation was GTV3D <ITV1 <ITV2 ≈ ITV3 < ITV4 < ITV5. The means ± SDs of these volumes were 11.1 ± 9.3 cc, 13.2 ± 10.5 cc, 14.9 ± 11.0 cc, 14.7 ± 11.4 cc, 15.9 ± 11.7 cc, and 16.4 ± 11.8 cc, respectively. All comparisons between the target volumes showed statistical significance (P≤.001), except for ITV2 and ITV3 (P=.594). The PVDs for all volume pairs correlated negatively with ETD (r≤-0.658, P≤.006) and positively with R3D (r≥0.503, P≤.047). The PVDs for pairs of ITV2 vs ITV5 and ITV5 vs ITV4 negatively correlated with ETD (r=0.502, -0.626; P=.047,.010). No other correlation was found. Conclusion: Uncertainties in individualized ITVs for SBRT of early stage NSCLC could effectively be minimized by combining information from 3DCT, 4DCT, and MIP. If these images cannot be efficiently contoured, a combination of ITVMIP and GTV3D could be an effective alternative. © 2013 Elsevier Inc. All rights reserved.

Authors
Ge, H; Cai, J; Kelsey, CR; Yin, F-F
MLA Citation
Ge, H, Cai, J, Kelsey, CR, and Yin, F-F. "Quantification and minimization of uncertainties of internal target volume for stereotactic body radiation therapy of lung cancer." International Journal of Radiation Oncology Biology Physics 85.2 (2013): 438-443.
Source
scival
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
85
Issue
2
Publish Date
2013
Start Page
438
End Page
443
DOI
10.1016/j.ijrobp.2012.04.032

Radiotherapy and Radiosurgery for Tumors of the Central Nervous System

In this article, the application of radiotherapy, alone and in combination with surgery and chemotherapy, in the treatment of metastases to the brain (the most common malignant brain lesion), primary malignant gliomas (the most common malignant primary brain tumor), and metastases to the osseous spine is reviewed. Brain metastases may be treated with surgical resection, whole-brain radiotherapy, stereotactic radiosurgery, or some combination of these treatments. The optimum treatment of brain metastases is a matter of controversy, and patient and disease factors favoring one treatment scheme over another are presented. © 2013 Elsevier Inc. All rights reserved.

Authors
Kirkpatrick, JP; Yin, F-F; Sampson, JH
MLA Citation
Kirkpatrick, JP, Yin, F-F, and Sampson, JH. "Radiotherapy and Radiosurgery for Tumors of the Central Nervous System." Surgical Oncology Clinics of North America (2013).
PMID
23622073
Source
scival
Published In
Surgical Oncology Clinics of North America
Publish Date
2013
DOI
10.1016/j.soc.2013.02.008

Uncertainties of 4-dimensional computed tomography-based tumor motion measurement for lung stereotactic body radiation therapy

Purpose: To evaluate how well tumor motion measured prior to treatment based on 4-dimensional computer tomography (4DCT) reflects actual tumor motion during beam-on throughout the course of treatment. Methods and materials: Twenty-three patients who had lung stereotactic body radiation therapy (SBRT) treatments were retrospectively selected. All patients had 4DCT simulation for treatment planning, from which tumor motion ranges were measured (R4DCT). Tumor motion was monitored during treatment using megavoltage (MV) imaging. Tumor motion trajectories were extracted from cine MV images and were used to determine mean and maximum tumor motion range (Mean RMV, Max RMV) throughout entire course of treatment. Comparison and correlations between mean and max RMV and R4DCT were calculated. Results: On average, an insignificant difference was found between mean RMV and R4DCT (P = .67, mean [± SD] difference = -0.7 [± 1.6] mm); meanwhile a significant difference was found between Max RMV and R4DCT (P = .03, mean [± SD] difference = 1.9 [± 1.6] mm). The difference between RMV and R4DCT was found inversely proportional to R4DCT (Y = -0.4X + 0.6, r = 0.76). Max RMV was greater than R4DCT in all patients; difference between the 2 showed no correlation with R4DCT (Y = -0.02X + 1.9, r = 0.05). Correlation between Mean RMV and R4DCT and between Max RMV and R4DCT can be expressed as Y = 0.7X (r = 0.88) and Y = 0.8X (r = 0.50), respectively. The same analysis performed on tumors that moved less than 5 mm from 4DCT revealed the following correlations: Y = 1.3X (r = 0.83) and Y = 1.7X (r = 0.49). Conclusions: Tumor motion measured from 4DCT approximates the overall average tumor motion range, but consistently underestimates the overall maximum tumor motion range. These findings may lead to a potential strategy for managing uncertainties of 4DCT in the application of lung SBRT. © 2013 American Society for Radiation Oncology.

Authors
Zhang, F; Kelsey, CR; Yoo, D; Yin, F-F; Cai, J
MLA Citation
Zhang, F, Kelsey, CR, Yoo, D, Yin, F-F, and Cai, J. "Uncertainties of 4-dimensional computed tomography-based tumor motion measurement for lung stereotactic body radiation therapy." Practical Radiation Oncology (2013).
PMID
24621433
Source
scival
Published In
Practical Radiation Oncology
Publish Date
2013
DOI
10.1016/j.prro.2013.02.009

Radiotherapy and Radiosurgery for Tumors of the Central Nervous System

In this article, the application of radiotherapy, alone and in combination with surgery and chemotherapy, in the treatment of metastases to the brain (the most common malignant brain lesion), primary malignant gliomas (the most common malignant primary brain tumor), and metastases to the osseous spine is reviewed. Brain metastases may be treated with surgical resection, whole-brain radiotherapy, stereotactic radiosurgery, or some combination of these treatments. The optimum treatment of brain metastases is a matter of controversy, and patient and disease factors favoring one approach over another are presented. © 2013 Elsevier Inc.

Authors
Kirkpatrick, JP; Yin, F-F; Sampson, JH
MLA Citation
Kirkpatrick, JP, Yin, F-F, and Sampson, JH. "Radiotherapy and Radiosurgery for Tumors of the Central Nervous System." Surgical Oncology Clinics of North America 22.3 (2013): 445-461.
Source
scival
Published In
Surgical Oncology Clinics of North America
Volume
22
Issue
3
Publish Date
2013
Start Page
445
End Page
461
DOI
10.1016/j.soc.2013.02.008

Quality requirements for stereotactic body radiation therapy (SBRT) in multi-institutional clinical trials

Clinical evidence have shown SBRT to be a tolerable, efficacious, and promising non-invasive therapy. Randomized prospective studies comparing surgery vs. SBRT in early-stage lung cancer are proposed to further investigate the relative survival, quality of life, and cost characteristics of these treatment paradigms. Accreditation and dosimetry requirements were carefully vetted for RTOG SBRT trials. Advanced technologies introduced since have posed additional challenges. This study provides an overview of the quality requirements including those for the recently introduced technologies. © 2013 Springer-Verlag.

Authors
Xiao, Y; Yin, F; Kong, FMS; Yue, J; Galvin, J
MLA Citation
Xiao, Y, Yin, F, Kong, FMS, Yue, J, and Galvin, J. "Quality requirements for stereotactic body radiation therapy (SBRT) in multi-institutional clinical trials." IFMBE Proceedings 39 IFMBE (2013): 2284-2287.
Source
scival
Published In
Ifmbe Proceedings
Volume
39 IFMBE
Publish Date
2013
Start Page
2284
End Page
2287
DOI
10.1007/978-3-642-29305-4_599

Adaptive stereotactic body radiation therapy planning for lung cancer

Purpose: To investigate the dosimetric effects of adaptive planning on lung stereotactic body radiation therapy (SBRT). Methods and Materials: Forty of 66 consecutive lung SBRT patients were selected for a retrospective adaptive planning study. CBCT images acquired at each fraction were used for treatment planning. Adaptive plans were created using the same planning parameters as the original CT-based plan, with the goal to achieve comparable comformality index (CI). For each patient, 2 cumulative plans, nonadaptive plan (PNON) and adaptive plan (PADP), were generated and compared for the following organs-at-risks (OARs): cord, esophagus, chest wall, and the lungs. Dosimetric comparison was performed between PNON and PADP for all 40 patients. Correlations were evaluated between changes in dosimetric metrics induced by adaptive planning and potential impacting factors, including tumor-to-OAR distances (dT-OAR), initial internal target volume (ITV1), ITV change (ΔITV), and effective ITV diameter change (ΔdITV). Results: 34 (85%) patients showed ITV decrease and 6 (15%) patients showed ITV increase throughout the course of lung SBRT. Percentage ITV change ranged from -59.6% to 13.0%, with a mean (±SD) of -21.0% (±21.4%). On average of all patients, PADP resulted in significantly (P=0 to.045) lower values for all dosimetric metrics. ΔdITV/dT-OAR was found to correlate with changes in dose to 5 cc (ΔD5cc) of esophagus (r=0.61) and dose to 30 cc (ΔD30cc) of chest wall (r=0.81). Stronger correlations between ΔdITV/dT-OAR and ΔD30cc of chest wall were discovered for peripheral (r=0.81) and central (r=0.84) tumors, respectively. Conclusions: Dosimetric effects of adaptive lung SBRT planning depend upon target volume changes and tumor-to-OAR distances. Adaptive lung SBRT can potentially reduce dose to adjacent OARs if patients present large tumor volume shrinkage during the treatment. © 2013 Elsevier Inc.

Authors
Qin, Y; Zhang, F; Yoo, DS; Kelsey, CR; Yin, F-F; Cai, J
MLA Citation
Qin, Y, Zhang, F, Yoo, DS, Kelsey, CR, Yin, F-F, and Cai, J. "Adaptive stereotactic body radiation therapy planning for lung cancer." International Journal of Radiation Oncology Biology Physics 87.1 (2013): 209-215.
Source
scival
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
1
Publish Date
2013
Start Page
209
End Page
215
DOI
10.1016/j.ijrobp.2013.05.008

In reply to Kumar et al

Authors
Ge, H; Cai, J; Kelsey, C; Yin, F-F
MLA Citation
Ge, H, Cai, J, Kelsey, C, and Yin, F-F. "In reply to Kumar et al." International Journal of Radiation Oncology Biology Physics 87.1 (2013): 5-6.
PMID
23920383
Source
scival
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
1
Publish Date
2013
Start Page
5
End Page
6
DOI
10.1016/j.ijrobp.2013.04.044

A knowledge-based approach to improving and homogenizing intensity modulated radiation therapy planning quality among treatment centers: An example application to prostate cancer planning

Purpose: Intensity modulated radiation therapy (IMRT) treatment planning can have wide variation among different treatment centers. We propose a system to leverage the IMRT planning experience of larger institutions to automatically create high-quality plans for outside clinics. We explore feasibility by generating plans for patient datasets from an outside institution by adapting plans from our institution. Methods and Materials: A knowledge database was created from 132 IMRT treatment plans for prostate cancer at our institution. The outside institution, a community hospital, provided the datasets for 55 prostate cancer cases, including their original treatment plans. For each "query" case from the outside institution, a similar "match" case was identified in the knowledge database, and the match case's plan parameters were then adapted and optimized to the query case by use of a semiautomated approach that required no expert planning knowledge. The plans generated with this knowledge-based approach were compared with the original treatment plans at several dose cutpoints. Results: Compared with the original plan, the knowledge-based plan had a significantly more homogeneous dose to the planning target volume and a significantly lower maximum dose. The volumes of the rectum, bladder, and femoral heads above all cutpoints were nominally lower for the knowledge-based plan; the reductions were significantly lower for the rectum. In 40% of cases, the knowledge-based plan had overall superior (lower) dose-volume histograms for rectum and bladder; in 54% of cases, the comparison was equivocal; in 6% of cases, the knowledge-based plan was inferior for both bladder and rectum. Conclusions: Knowledge-based planning was superior or equivalent to the original plan in 95% of cases. The knowledge-based approach shows promise for homogenizing plan quality by transferring planning expertise from more experienced to less experienced institutions. © 2013 Elsevier Inc.

Authors
Good, D; Lo, J; Lee, WR; Wu, QJ; Yin, F-F; Das, SK
MLA Citation
Good, D, Lo, J, Lee, WR, Wu, QJ, Yin, F-F, and Das, SK. "A knowledge-based approach to improving and homogenizing intensity modulated radiation therapy planning quality among treatment centers: An example application to prostate cancer planning." International Journal of Radiation Oncology Biology Physics 87.1 (2013): 176-181.
Source
scival
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
87
Issue
1
Publish Date
2013
Start Page
176
End Page
181
DOI
10.1016/j.ijrobp.2013.03.015

The effect of motion on IMRT - looking at interplay with 3D measurements

Authors
Thomas, A; Yan, H; Oldham, M; Juang, T; Adamovics, J; Yin, FF; IOP,
MLA Citation
Thomas, A, Yan, H, Oldham, M, Juang, T, Adamovics, J, Yin, FF, and IOP, . "The effect of motion on IMRT - looking at interplay with 3D measurements." 2013.
PMID
26877756
Source
wos-lite
Published In
Journal of Physics
Volume
444
Publish Date
2013
DOI
10.1088/1742-6596/444/1/012049

Generation of Virtual Monochromatic (VM) CBCT from Dual kV/MV Beam Projections

Authors
Li, H; Yin, F
MLA Citation
Li, H, and Yin, F. "Generation of Virtual Monochromatic (VM) CBCT from Dual kV/MV Beam Projections." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S83
End Page
S84

Functional and Molecular Imaging of the Axilla as the Patient Is in Position for Radiation Therapy Using a Robotic Multi-pinhole SPECT System

Authors
Yan, S; Bowsher, J; Yin, F
MLA Citation
Yan, S, Bowsher, J, and Yin, F. "Functional and Molecular Imaging of the Axilla as the Patient Is in Position for Radiation Therapy Using a Robotic Multi-pinhole SPECT System." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S247
End Page
S248

Reproducibility of tumor motion probability distribution function in stereotactic body radiation therapy of lung cancer.

PURPOSE: To evaluate the reproducibility of tumor motion probability distribution function (PDF) in stereotactic body radiation therapy (SBRT) of lung cancer using cine megavoltage (MV) images. METHODS AND MATERIALS: Cine MV images of 20 patients acquired during three-dimensional conformal (6-11 beams) SBRT treatments were retrospectively analyzed to extract tumor motion trajectories. For each patient, tumor motion PDFs were generated per fraction (PDF(n)) using three selected "usable" beams. Patients without at least three usable beams were excluded from the study. Fractional PDF reproducibility (R(n)) was calculated as the Dice similarity coefficient between PDF(n) to a "ground-truth" PDF (PDF(g)), which was generated using the selected beams of all fractions. The mean of R(n), labeled as R(m), was calculated for each patient and correlated to the patient's mean tumor motion rang (A(m)). Change of R(m) during the course of SBRT treatments was also evaluated. Intra- and intersubject coefficient of variation (CV) of R(m) and A(m) were determined. RESULTS: Thirteen patients had at least three usable beams and were analyzed. The mean of R(m) was 0.87 (range, 0.84-0.95). The mean of A(m) was 3.18 mm (range, 0.46-7.80 mm). R(m) was found to decrease as A(m) increases following an equation of R(m) = 0.17e(-0.9Am) + 0.84. R(m) also decreased slightly throughout the course of treatments. Intersubject CV of R(m) (0.05) was comparable to intrasubject CV of R(m) (range, 0.02-0.09); intersubject CV of A(m) (0.73) was significantly greater than intrasubject CV of A(m) (range, 0.09-0.24). CONCLUSIONS: Tumor motion PDF can be determined using cine MV images acquired during the treatments. The reproducibility of lung tumor motion PDF decreased exponentially as the tumor motion range increased and decreased slightly throughout the course of the treatments.

Authors
Zhang, F; Hu, J; Kelsey, CR; Yoo, D; Yin, F-F; Cai, J
MLA Citation
Zhang, F, Hu, J, Kelsey, CR, Yoo, D, Yin, F-F, and Cai, J. "Reproducibility of tumor motion probability distribution function in stereotactic body radiation therapy of lung cancer." Int J Radiat Oncol Biol Phys 84.3 (November 1, 2012): 861-866.
PMID
22494586
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
861
End Page
866
DOI
10.1016/j.ijrobp.2012.01.037

Dosimetric Evaluation of Flattening Filter-free (FFF) Photon Beams for Lung SBRT

Authors
Chen, Q; Cai, J; Wu, Q; Yin, F
MLA Citation
Chen, Q, Cai, J, Wu, Q, and Yin, F. "Dosimetric Evaluation of Flattening Filter-free (FFF) Photon Beams for Lung SBRT." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S609
End Page
S609

Impact of Patient Anatomy Variations on a Fourier Technique for Markerless 4D-CBCT

Authors
Vergalasova, I; Cai, J; Yin, F
MLA Citation
Vergalasova, I, Cai, J, and Yin, F. "Impact of Patient Anatomy Variations on a Fourier Technique for Markerless 4D-CBCT." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S719
End Page
S719

Prostate SBRT in 5 Fractions: Initial Report on Dosimetric Results and IGRT Experiences

Authors
Li, T; Wu, Q; Yuan, L; Yin, F; Lee, W
MLA Citation
Li, T, Wu, Q, Yuan, L, Yin, F, and Lee, W. "Prostate SBRT in 5 Fractions: Initial Report on Dosimetric Results and IGRT Experiences." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S815
End Page
S815

Knowledge-based Organ-at-Risk Sparing Models and Individualized Trade-offs in Intensity Modulated Radiation Therapy Planning

Authors
Wu, Q; Yuan, L; Li, T; Kirkpatrick, J; Yin, F; Ge, Y
MLA Citation
Wu, Q, Yuan, L, Li, T, Kirkpatrick, J, Yin, F, and Ge, Y. "Knowledge-based Organ-at-Risk Sparing Models and Individualized Trade-offs in Intensity Modulated Radiation Therapy Planning." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S27
End Page
S27

Can Standard Radiation Therapy Quality Assurance (QA) Detect Potential Delivery Errors?

Authors
Ren, L; O'Daniel, J; Adamson, J; Yan, H; Yin, F
MLA Citation
Ren, L, O'Daniel, J, Adamson, J, Yan, H, and Yin, F. "Can Standard Radiation Therapy Quality Assurance (QA) Detect Potential Delivery Errors?." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S779
End Page
S779

Evaluation of IMRT and VMAT for Head-and-Neck Cancer With Flattening Filter-free (FFF) Beams

Authors
Wu, Q; Yoo, S; Das, S; Yin, F
MLA Citation
Wu, Q, Yoo, S, Das, S, and Yin, F. "Evaluation of IMRT and VMAT for Head-and-Neck Cancer With Flattening Filter-free (FFF) Beams." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S863
End Page
S863

Partial Breast Extracranial Radiosurgery: A Dosimetric Evaluation of Treatment Delivery Accuracy

Authors
Yoo, S; O'Daniel, J; Blitzblau, R; Wu, Q; Yin, F; Horton, J
MLA Citation
Yoo, S, O'Daniel, J, Blitzblau, R, Wu, Q, Yin, F, and Horton, J. "Partial Breast Extracranial Radiosurgery: A Dosimetric Evaluation of Treatment Delivery Accuracy." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S243
End Page
S243

Commissioning and dosimetric characteristics of TrueBeam system: composite data of three TrueBeam machines.

PURPOSE: A TrueBeam linear accelerator (TB-LINAC) is designed to deliver traditionally flattened and flattening-filter-free (FFF) beams. Although it has been widely adopted in many clinics for patient treatment, limited information is available related to commissioning of this type of machine. In this work, commissioning data of three units were measured, and multiunit comparison was presented to provide valuable insights and reliable evaluations on the characteristics of the new treatment system. METHODS: The TB-LINAC is equipped with newly designed waveguide, carousel assembly, monitoring control, and integrated imaging systems. Each machine in this study has 4, 6, 8, 10, 15 MV flattened photon beams, and 6 MV and 10 MV FFF photon beams as well as 6, 9, 12, 16, 20, and 22 MeV electron beams. Dosimetric characteristics of the three new TB-LINAC treatment units are systematically measured for commissioning. High-resolution diode detectors and ion chambers were used to measure dosimetric data for a range of field sizes from 10 × 10 to 400 × 400 mm(2). The composite dosimetric data of the three units are presented in this work. The commissioning of intensity modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), image-guided radiation therapy, and gating systems are also illustrated. Critical considerations of P(ion) of FFF photon beams and small field dosimetric measurements were investigated. RESULTS: The authors found all PDDs and profiles matched well among the three machines. Beam data were quantitatively compared and combined through average to yield composite beam data. The discrepancies among the machines were quantified using standard deviation (SD). The mean SD of the PDDs among the three units is 0.12%, and the mean SD of the profiles is 0.40% for 10 MV FFF open fields. The variations of P(ion) of the chamber CC13 is 1.2 ± 0.1% under 6 MV FFF and 2.0 ± 0.5% under 10 MV FFF from dmax to the 18 cm-off-axis point at 35 cm depth under 40 × 40 cm(2). The mean penumbra of crossplane flattened photon beams at collimator angle of 0° is measured from 5.88 ± 0.09 to 5.99 ± 0.13 mm from 4 to 15 MV at 10 cm depth of 100 × 100 mm(2). The mean penumbra of crossplane beams at collimator angle of 0° is measured as 3.70 ± 0.21 and 4.83 ± 0.04 mm for 6 MV FFF and 10 MV FFF, respectively, at 10 cm depth with a field size of 5 × 5 cm(2). The end-to-end test procedures of both IMRT and VMAT were performed for various energy modes. The mean ion chamber measurements of three units showed less than 2% between measurement and calculation; the mean MultiCube ICA measurements demonstrated over 90% pixels passing gamma analysis (3%, 3 mm, 5% threshold). The imaging dosimetric data of KV planar imaging and CBCT demonstrated improved consistency with vendor specifications and dose reduction for certain imaging protocols. The gated output verification showed a discrepancy of 0.05% or less between gating radiation delivery and nongating radiation delivery. CONCLUSIONS: The commissioning data indicated good consistency among the three TB-LINAC units. The commissioning data provided us valuable insights and reliable evaluations on the characteristics of the new treatment system. The systematically measured data might be useful for future reference.

Authors
Chang, Z; Wu, Q; Adamson, J; Ren, L; Bowsher, J; Yan, H; Thomas, A; Yin, F-F
MLA Citation
Chang, Z, Wu, Q, Adamson, J, Ren, L, Bowsher, J, Yan, H, Thomas, A, and Yin, F-F. "Commissioning and dosimetric characteristics of TrueBeam system: composite data of three TrueBeam machines." Med Phys 39.11 (November 2012): 6981-7018.
PMID
23127092
Source
pubmed
Published In
Medical physics
Volume
39
Issue
11
Publish Date
2012
Start Page
6981
End Page
7018
DOI
10.1118/1.4762682

Quantitative analysis of the factors which affect the interpatient organ-at-risk dose sparing variation in IMRT plans.

PURPOSE: The authors present an evidence-based approach to quantify the effects of an array of patient anatomical features of the planning target volumes (PTVs) and organs-at-risk (OARs) and their spatial relationships on the interpatient OAR dose sparing variation in intensity modulated radiation therapy (IMRT) plans by learning from a database of high-quality prior plans. METHODS: The authors formulized the dependence of OAR dose volume histograms (DVHs) on patient anatomical factors into feature models which were learned from prior plans by a stepwise multiple regression method. IMRT plans for 64 prostate, 82 head-and-neck (HN) treatments were used to train the models. Two major groups of anatomical features were considered in this study: the volumetric information and the spatial information. The geometry of OARs relative to PTV is represented by the distance-to-target histogram, DTH. Important anatomical and dosimetric features were extracted from DTH and DVH by principal component analysis. The final models were tested by additional 24 prostate and 24 HN plans. RESULTS: Significant patient anatomical factors contributing to OAR dose sparing in prostate and HN IMRT plans have been analyzed and identified. They are: the median distance between OAR and PTV, the portion of OAR volume within an OAR specific distance range, and the volumetric factors: the fraction of OAR volume which overlaps with PTV and the portion of OAR volume outside the primary treatment field. Overall, the determination coefficients R(2) for predicting the first principal component score (PCS1) of the OAR DVH by the above factors are above 0.68 for all the OARs and they are more than 0.53 for predicting the second principal component score (PCS2) of the OAR DVHs except brainstem and spinal cord. Thus, the above set of anatomical features combined has captured significant portions of the DVH variations for the OARs in prostate and HN plans. To test how well these features capture the interpatient organ dose sparing variations in general, the DVHs and specific dose-volume indices calculated from the regression models were compared with the actual DVHs and dose-volume indices from each patient's plan in the validation dataset. The dose-volume indices compared were V99%, V85%, and V50% for bladder and rectum in prostate plans and parotids median dose in HN plans. The authors found that for the bladder and rectum models, 17 out of 24 plans (71%) were within 6% OAR volume error and 21 plans (85%) were within 10% error; For the parotids model, the median dose values for 30 parotids out of 48 (63%) were within 6% prescription dose error and the values in 40 parotids (83%) were within 10% error. CONCLUSIONS: Quantitative analysis of patient anatomical features and their correlation with OAR dose sparing has identified a number of important factors that explain significant amount of interpatient DVH variations in OARs. These factors can be incorporated into evidence-based learning models as effective features to provide patient-specific OAR dose sparing goals.

Authors
Yuan, L; Ge, Y; Lee, WR; Yin, FF; Kirkpatrick, JP; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Lee, WR, Yin, FF, Kirkpatrick, JP, and Wu, QJ. "Quantitative analysis of the factors which affect the interpatient organ-at-risk dose sparing variation in IMRT plans." Med Phys 39.11 (November 2012): 6868-6878.
PMID
23127079
Source
pubmed
Published In
Medical physics
Volume
39
Issue
11
Publish Date
2012
Start Page
6868
End Page
6878
DOI
10.1118/1.4757927

Stereotactic body radiotherapy treatment of extracranial metastases.

Radiotherapy is an integral treatment for patients with metastatic cancer, although it is usually reserved for palliation of pain, dyspnoea, oedema, bleeding and neurological symptoms. However, the administration of high-precision radiotherapy, termed stereotactic body radiotherapy (SBRT), has the potential to significantly affect the disease course for some patients with metastatic cancer by delivering high doses of radiation to the secondary tumours with limited high-dose delivery to adjacent healthy tissues. Indeed, such accurate delivery has been firmly established as a therapy for medically inoperable early-stage non-small-cell lung cancer. To date, the technique has demonstrated improvements in controlling metastasis and, in some cases, improved palliation compared with conventionally fractionated radiotherapy. Active areas of research in SBRT include patient selection for curative intent, optimization of SBRT planning techniques, dosing schema and integration of SBRT into systemic therapies. Given the improvements in cytotoxic and targeted therapies over the past decade, studies testing the careful integration of SBRT into standard systemic therapy regimens are needed. Further investigations are also needed to understand the basic biological mechanisms underlying SBRT because they are likely to be different to those mechanisms in conventional radiotherapy.

Authors
Salama, JK; Kirkpatrick, JP; Yin, F-F
MLA Citation
Salama, JK, Kirkpatrick, JP, and Yin, F-F. "Stereotactic body radiotherapy treatment of extracranial metastases." Nat Rev Clin Oncol 9.11 (November 2012): 654-665. (Review)
PMID
23007273
Source
pubmed
Published In
Nature Reviews Clinical Oncology
Volume
9
Issue
11
Publish Date
2012
Start Page
654
End Page
665
DOI
10.1038/nrclinonc.2012.166

Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs.

PURPOSE: To implement dual-energy imaging technique for virtual monochromatic (VM) and linearly mixed (LM) cone beam CTs (CBCTs) and to demonstrate their potential applications in metal artifact reduction and contrast enhancement in image-guided radiation therapy (IGRT). METHODS: A bench-top CBCT system was used to acquire 80 kVp and 150 kVp projections, with an additional 0.8 mm tin filtration. To implement the VM technique, these projections were first decomposed into acrylic and aluminum basis material projections to synthesize VM projections, which were then used to reconstruct VM CBCTs. The effect of VM CBCT on the metal artifact reduction was evaluated with an in-house titanium-BB phantom. The optimal VM energy to maximize contrast-to-noise ratio (CNR) for iodine contrast and minimize beam hardening in VM CBCT was determined using a water phantom containing two iodine concentrations. The LM technique was implemented by linearly combining the low-energy (80 kVp) and high-energy (150 kVp) CBCTs. The dose partitioning between low-energy and high-energy CBCTs was varied (20%, 40%, 60%, and 80% for low-energy) while keeping total dose approximately equal to single-energy CBCTs, measured using an ion chamber. Noise levels and CNRs for four tissue types were investigated for dual-energy LM CBCTs in comparison with single-energy CBCTs at 80, 100, 125, and 150 kVp. RESULTS: The VM technique showed substantial reduction of metal artifacts at 100 keV with a 40% reduction in the background standard deviation compared to a 125 kVp single-energy scan of equal dose. The VM energy to maximize CNR for both iodine concentrations and minimize beam hardening in the metal-free object was 50 keV and 60 keV, respectively. The difference of average noise levels measured in the phantom background was 1.2% between dual-energy LM CBCTs and equivalent-dose single-energy CBCTs. CNR values in the LM CBCTs of any dose partitioning are better than those of 150 kVp single-energy CBCTs. The average CNR for four tissue types with 80% dose fraction at low-energy showed 9.0% and 4.1% improvement relative to 100 kVp and 125 kVp single-energy CBCTs, respectively. CNRs for low-contrast objects improved as dose partitioning was more heavily weighted toward low-energy (80 kVp) for LM CBCTs. CONCLUSIONS: Dual-energy CBCT imaging techniques were implemented to synthesize VM CBCT and LM CBCTs. VM CBCT was effective at achieving metal artifact reduction. Depending on the dose-partitioning scheme, LM CBCT demonstrated the potential to improve CNR for low contrast objects compared to single-energy CBCT acquired with equivalent dose.

Authors
Li, H; Giles, W; Ren, L; Bowsher, J; Yin, F-F
MLA Citation
Li, H, Giles, W, Ren, L, Bowsher, J, and Yin, F-F. "Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs." Med Phys 39.10 (October 2012): 6056-6064.
PMID
23039644
Source
pubmed
Published In
Medical physics
Volume
39
Issue
10
Publish Date
2012
Start Page
6056
End Page
6064
DOI
10.1118/1.4752212

Establishing a framework to implement 4D XCAT phantom for 4D radiotherapy research.

AIMS: To establish a framework to implement the 4D integrated extended cardiac torso (XCAT) digital phantom for 4D radiotherapy (RT) research. MATERIALS AND METHODS: A computer program was developed to facilitate the characterization and implementation of the 4D XCAT phantom. The program can (1) generate 4D XCAT images with customized parameter files; (2) review 4D XCAT images; (3) generate composite images from 4D XCAT images; (4) track motion of selected region-of-interested (ROI); (5) convert XCAT raw binary images into DICOM format; (6) analyse clinically acquired 4DCT images and real-time position management (RPM) respiratory signal. Motion tracking algorithm was validated by comparing with manual method. Major characteristics of the 4D XCAT phantom were studied. RESULTS: The comparison between motion tracking and manual measurements of lesion motion trajectory showed a small difference between them (mean difference in motion amplitude: 1.2 mm). The maximum lesion motion decreased nearly linearly (R 2 = 0.97) as its distance to the diaphragm (DD) increased. At any given DD, lesion motion amplitude increased nearly linearly (R 2 range: 0.89 to 0.95) as the inputted diaphragm motion increased. For a given diaphragm motion, the lesion motion is independent of the lesion size at any given DD. The 4D XCAT phantom can closely reproduce irregular breathing profile. The end-to-end test showed that clinically comparable treatment plans can be generated successfully based on 4D XCAT images. CONCLUSIONS: An integrated computer program has been developed to generate, review, analyse, process, and export the 4D XCAT images. A framework has been established to implement the 4D XCAT phantom for 4D RT research.

Authors
Panta, RK; Segars, P; Yin, F-F; Cai, J
MLA Citation
Panta, RK, Segars, P, Yin, F-F, and Cai, J. "Establishing a framework to implement 4D XCAT phantom for 4D radiotherapy research." J Cancer Res Ther 8.4 (October 2012): 565-570.
PMID
23361276
Source
pubmed
Published In
Journal of Cancer Research and Therapeutics
Volume
8
Issue
4
Publish Date
2012
Start Page
565
End Page
570
DOI
10.4103/0973-1482.106539

Feasibility study of a synchronized-moving-grid (SMOG) system to improve image quality in cone-beam computed tomography (CBCT).

PURPOSE: To evaluate the feasibility of a synchronized moving grid (SMOG) system to remove scatter artifacts, improve the contrast-to-noise ratio (CNR), and reduce image lag artifacts in cone-beam CT (CBCT). METHODS: The SMOG system proposed here uses a rapidly oscillating, synchronized moving grid attached to the kV source. Multiple partial projections are taken at different grid positions to form a complete projection in each gantry position, before the gantry moves to the next position during a scan. The grid has a low transmission factor, and it is used for both scatter reduction and scatter measurement for postscan scatter correction. Experimental studies using a static grid and an enlarged CATphan phantom were performed to evaluate the potential CNR enhancement for different SMOG exposure numbers (1, 2, and 4). Simulation studies were performed to evaluate the image lag correction for different exposure numbers (2, 3, and 4) and grid interspace widths in SMOG using the data from an anthropomorphic pelvis phantom scan. Imaging dose of SMOG was also estimated by measuring the imaging dose in a CIRS CT dose phantom using a static grid. RESULTS: SMOG can enhance the CNR by 16% and 13% when increasing exposure number from 1 to 2 and from 2 to 4, respectively. This enhancement was more dramatic for larger phantoms and smaller initial exposure numbers. Simulation results indicated that SMOG could reduce the lag to less than 4.3% for 2-exposure mode and to less than 0.8% for 3-exposure mode when the grid interspace width was 1.4 cm. Increasing the number of exposures in SMOG dramatically reduced the residual lag in the image. Reducing the grid interspace width somewhat reduced the residual lag. Skin line artifacts were removed entirely in SMOG. Point dose measurement showed that imaging dose of SMOG at isocenter was similar as that of a conventional CBCT. CONCLUSIONS: Compared to our previously developed static-grid dual-rotation method, the proposed SMOG technique has the advantages of enhancing the CNR, correcting the image lag, and reducing the delivery time. Once implemented, SMOG has the potential to remove scatter and image lag artifacts, and significantly enhance CNR for CBCT using the same scanning time as conventional CBCT.

Authors
Ren, L; Yin, F-F; Chetty, IJ; Jaffray, DA; Jin, J-Y
MLA Citation
Ren, L, Yin, F-F, Chetty, IJ, Jaffray, DA, and Jin, J-Y. "Feasibility study of a synchronized-moving-grid (SMOG) system to improve image quality in cone-beam computed tomography (CBCT)." Med Phys 39.8 (August 2012): 5099-5110.
PMID
22894435
Source
pubmed
Published In
Medical physics
Volume
39
Issue
8
Publish Date
2012
Start Page
5099
End Page
5110
DOI
10.1118/1.4736826

Imaging system QA of a medical accelerator, Novalis Tx, for IGRT per TG 142: our 1 year experience.

American Association of Physicists in Medicine (AAPM) task group (TG) 142 has recently published a report to update recommendations of the AAPM TG 40 report and add new recommendations concerning medical accelerators in the era of image-guided radiation therapy (IGRT). The recommendations of AAPM TG 142 on IGRT are timely. In our institute, we established a comprehensive imaging QA program on a medical accelerator based on AAPM TG 142 and implemented it successfully. In this paper, we share our one-year experience and performance evaluation of an OBI capable linear accelerator, Novalis Tx, per TG 142 guidelines.

Authors
Chang, Z; Bowsher, J; Cai, J; Yoo, S; Wang, Z; Adamson, J; Ren, L; Yin, F-F
MLA Citation
Chang, Z, Bowsher, J, Cai, J, Yoo, S, Wang, Z, Adamson, J, Ren, L, and Yin, F-F. "Imaging system QA of a medical accelerator, Novalis Tx, for IGRT per TG 142: our 1 year experience. (Published online)" J Appl Clin Med Phys 13.4 (July 5, 2012): 3754-.
PMID
22766946
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
13
Issue
4
Publish Date
2012
Start Page
3754

Decision Support for Radiation Therapy

Authors
Yin, F
MLA Citation
Yin, F. "Decision Support for Radiation Therapy." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3949
End Page
3949

Credentialing Results From a Spine Anthropomorphic Phantom

Authors
Molineu, A; Alvarez, P; Hernandez, N; Yin, F; Followill, D
MLA Citation
Molineu, A, Alvarez, P, Hernandez, N, Yin, F, and Followill, D. "Credentialing Results From a Spine Anthropomorphic Phantom." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3996
End Page
3996

A Novel Technique for Estimating and Correcting Cross-Scatter in Dual-Source CBCT

Authors
Giles, W; Bowsher, J; Li, H; Yin, F
MLA Citation
Giles, W, Bowsher, J, Li, H, and Yin, F. "A Novel Technique for Estimating and Correcting Cross-Scatter in Dual-Source CBCT." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3891
End Page
3891

A Robotic Multi-Pinhole SPECT System for Onboard and Other Region-Of-Interest Imaging

Authors
Bowsher, J; Yan, S; Roper, J; Giles, W; Yin, F
MLA Citation
Bowsher, J, Yan, S, Roper, J, Giles, W, and Yin, F. "A Robotic Multi-Pinhole SPECT System for Onboard and Other Region-Of-Interest Imaging." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3887
End Page
3888

TU-E-BRB-04: Adaptive Stereotactic-Body Radiation Therapy (SBRT) Planning for Lung Cancer.

Tumor shrinkage during lung SBRT has been reported. Adaptive SBRT planning can potentially escalate dose to the target and mitigate dose to surrounding tissues. In this study, we investigated dosimetric effects of adaptive lung SBRT planning using cone-bean CT (CBCT) images.48 patients who had SBRT treatments for lung cancer in our institution were included in this study. All patients underwent a 3D helical CT scan and 4DCT scan for treatment planning. Treatments were delivered on Linac machines equipped with kV-OBI, CBCT, and MV EPID. CBCT images of all patients were retrospectively analyzed to determine tumor size changes. 10 patients with the largest percentages of tumor shrinkage were selected for adaptive planning. Plans were created on CBCT images of each fraction using the same planning parameters as the original CT-based plans. ITV was contoured on CBCT. PTV was generated by adding 5 mm margin to ITV. Two accumulative dose plans, non-adaptive (P-NON) and adaptive (P-ADP), were determined for each patient using deformable image registration via Velocity AI. Dosimetric comparisons between PNON and PADP were performed for all OARs using RTOG0915 metrics. Statistical significances were tested using paired t-test with a significance level of 0.05.Comformality ranged from 1.03 to 1.41, with small intra-subject variations (ranged from 0.01 to 0.06). Compared to PNON, PADP reduced all dosimetric metrics and significantly in the following (p-value range: 0.02-0.04): V20Gy of lungs; D0.35cc, D1.2cc and maximum dose of cord, D5cc and maximum dose of esophagus, D30cc of chest wall, and D15cc of heart. Coverage to original GTV is comparable in two plans.Adaptive SBRT planning for selected patients resulted in significant dose reduction for adjacent OARs. It has the potential to further escalate dose to the target and mitigate dose to surrounding tissues.

Authors
Qin, Y; Zhang, F; Kelsey, C; Yoo, D; Yin, F; Cai, J
MLA Citation
Qin, Y, Zhang, F, Kelsey, C, Yoo, D, Yin, F, and Cai, J. "TU-E-BRB-04: Adaptive Stereotactic-Body Radiation Therapy (SBRT) Planning for Lung Cancer." Medical physics 39.6Part24 (June 2012): 3908-.
PMID
28518661
Source
epmc
Published In
Medical physics
Volume
39
Issue
6Part24
Publish Date
2012
Start Page
3908
DOI
10.1118/1.4735953

MO-A-213AB-04: Verification of 4D Dose Delivery Using 4D Digital Human Phantom.

At present, techniques of 4D dose verification in radiation therapy for lung cancers associated with respiratory motion are very limited, due to either lack of patient anatomy or breathing information. The aim of this study is to develop a 4D dose verification technique based on XCAT phantom which incorporates both patient anatomy and respiratory mechanics.The 4D-XCAT phantom which possesses patient specific anatomy and allows input of respiratory parameters was generated using an integrated Matlab program. 10-phase 4DCT, MIP, and AIP images generated from 4D-XCAT were used for designing a 3D conformal treatment plan. Real-time dose delivery was simulated by calculating the deposited dose in each phase of 4D-XCAT for each beam with fixed individual planning dose. The 4D delivered dose was determined by accumulating dose deposition of all beams in all phases using deformable image registration implemented in VelocityAl software. The planned and delivered doses were compared based on target coverage and DVHs of OARs (lungs, cord, heart, and esophagus).Target volume coverage was 97.5% in the simulated real-time delivery, as compared to 95% as planned based on AIP. Maximum cord dose, maximum esophagus dose, mean heart dose, and V20Gy of lung were comparable between the planned and delivered dose; the relative difference were 0.3%, 4.0%, 0%, and 2.8%, respectively. These results indicates AIP-based planning was a close representation of the real 4D dose delivery for both target and OARs when the breathing pattern is regular and reproducible.A framework has been successfully established for verifying 4D dose delivery using the 4D-XCAT phantom and deformable image registration. This verification method is capable of incorporating specific patient anatomy and respiratory mechanics.

Authors
Zhang, F; Qin, Y; Segars, W; Yin, F; Cai, J
MLA Citation
Zhang, F, Qin, Y, Segars, W, Yin, F, and Cai, J. "MO-A-213AB-04: Verification of 4D Dose Delivery Using 4D Digital Human Phantom." Medical physics 39.6Part20 (June 2012): 3859-.
PMID
28517547
Source
epmc
Published In
Medical physics
Volume
39
Issue
6Part20
Publish Date
2012
Start Page
3859
DOI
10.1118/1.4735756

SU-D-218-02: 4D-MRI Based on Body Area (BA) Surrogate and Sagittal Image Acquisition.

4D-MRI based on body area (BA) surrogate using axial image acquisition has been demonstrated. Since respiratory motion mostly occurs in the superior-inferior (SI) direction, it is expected that sagittal acquisition may provide more robust and accurate breathing signal than axial acquisition. The aim of this study was to investigate the feasibility of extracting breathing signals from sagittal images using BA surrogate and its application in 4D-MRI.7 human subjects were imaged continuously in a single (n=5) or multiple (n=2) sagittal planes using a steady-state precession sequence. Imaging parameters were: TR/TE, 3.7ms/1.21ms; Matrix, 256×166; FOV, 350×300mm; flip angle, 52°; slice thickness, 5mm; frame rate: ∼3 frames/s. Imaging time per slice is 2 minutes for single slice acquisition and ∼10 seconds for multi-slice acquisition. Breathing signals were generated for all subjects by tracking the change of BA. The multi-slice sagittal acquisition was performed on a MRI- compatible motion phantom with a cylindrical gel target and was simulated on a 4D digital human phantom. Breathing signals were extracted from the sagittal images using the BA surrogate. Respiratory phases were calculated. 4D-MRI of both phantoms were retrospectively reconstructed based on the respiratory phases.Breathing signals extracted from both single slice and multi-slice sagittal acquisitions showed stable and well- characterized patterns. 4D-MRI of the physical phantom showed clear sinusoidal motion of the gel target in all three planes with minimal artifacts. Simulated '4D-MRI' of the 4D digital phantom matched well with original images: the mean absolute difference in motion amplitude of the 'tumor' was 0.4±0.3mm. Small artifacts of discontinuity were observed in the SI direction in certain phases.It is feasible to extract breathing signals from sagittal images for 4D-MRI application. Further investigation is needed to test whether sagittal acquisition is more robust and accurate than axial acquisition for breathing signal extraction.

Authors
Qin, Y; Chang, Z; Segars, W; Yin, F; Cai, J
MLA Citation
Qin, Y, Chang, Z, Segars, W, Yin, F, and Cai, J. "SU-D-218-02: 4D-MRI Based on Body Area (BA) Surrogate and Sagittal Image Acquisition." Medical physics 39.6Part3 (June 2012): 3622-.
PMID
28517421
Source
epmc
Published In
Medical physics
Volume
39
Issue
6Part3
Publish Date
2012
Start Page
3622
DOI
10.1118/1.4734705

SU-E-J-32: Evaluation of the Dosimetric Accuracy of Stereotactic Radiosurgery with Cone-Beam Computed Tomography Localization.

To evaluate the dosimetric accuracy of stereotactic radiosurgery (SRS) with cone-beam computed tomography (CBCT) guided patient localization.A Novalis TX linear accelerator with high definition multileaf collimator (HDMLC) was used for SRS treatments. 20 patients immobilized with the noninvasive BrainLab U-frame system and thermoplastic mask were selected to evaluate the dosimetric accuracy of CBCT image-guided SRS by the BrainLab iPlan Phantom Mapping module. The contours of the PTV and critical organ were transferred directly from the planning CT and MR images to the CBCT images after image registrations. The delivered dose distributions could be calculated and analyzed by copying the original treatment plans to the CBCT images and assigning the treatment isocenters on the CBCT images according to the couch shifts acquired after planning CT and CBCT image registrations. The CT electron density calibration curve used for original plans was also applied for the CBCT-based planning.The average minimum dose, mean dose, and maximum dose in PTV of the original plans and the CBCT plans were 95.45%±3.80% and 92.88%±3.25%, 110.59%±1.81% and 110.11%±2.40%, 116.55%±3.11% and 115.93%±2.78%, respectively. In the original treatment plans, the average 100% prescription dose coverage of GTV and PTV were 99.99% and 99.81%, respectively. In the CBCT plans, the average 100% prescription dose coverage of GTV and PTV were 99.90% and 98.20%, respectively. The average conformity index of the original plans and the CBCT plans were 1.846 and 1.863, respectively.Data demonstrated that the dose distributions calculated in the CBCT images were comparable to the original treatment plans. The CBCT plans only indicated a slightly higher conformity index and lower average minimum dose, mean dose, maximum dose, GTV coverage, and PTV coverage compared to the original treatment plans. Therefore, the CBCT guided localization was considered effective to assure dosimetric accuracy in SRS.

Authors
Tseng, T; Chang, Z; Yin, F; Wang, Z
MLA Citation
Tseng, T, Chang, Z, Yin, F, and Wang, Z. "SU-E-J-32: Evaluation of the Dosimetric Accuracy of Stereotactic Radiosurgery with Cone-Beam Computed Tomography Localization." Medical physics 39.6Part6 (June 2012): 3659-.
PMID
28517578
Source
epmc
Published In
Medical physics
Volume
39
Issue
6Part6
Publish Date
2012
Start Page
3659
DOI
10.1118/1.4734865

TH-E-218-01: Dual-Energy CBCT Imaging for Metal Artifact Reduction and Contrast Enhancement

Authors
Li, H; Giles, W; Ren, L; Bowsher, J; Yin, F
MLA Citation
Li, H, Giles, W, Ren, L, Bowsher, J, and Yin, F. "TH-E-218-01: Dual-Energy CBCT Imaging for Metal Artifact Reduction and Contrast Enhancement." June 2012.
Source
crossref
Published In
Medical physics
Volume
39
Issue
6Part31
Publish Date
2012
Start Page
4017
End Page
4017
DOI
10.1118/1.4736387

WE-A-217A-09: Evaluating Radiation-Induced White Matter Changes in Patients with Recurrent Malignant Gliomas under Treatment of Stereotactic Radiosurgery Using Diffusion Tensor Imaging

Authors
Chang, Z; Kirkpatrick, J; Cai, J; Wang, Z; Yin, F
MLA Citation
Chang, Z, Kirkpatrick, J, Cai, J, Wang, Z, and Yin, F. "WE-A-217A-09: Evaluating Radiation-Induced White Matter Changes in Patients with Recurrent Malignant Gliomas under Treatment of Stereotactic Radiosurgery Using Diffusion Tensor Imaging." June 2012.
Source
crossref
Published In
Medical physics
Volume
39
Issue
6Part26
Publish Date
2012
Start Page
3937
End Page
3937
DOI
10.1118/1.4736067

TH-E-BRB-11: Benchmarking Flattening-Filter Free Photons for IMRT/VMAT

Authors
Ashmeg, S; O'Daniel, J; Wu, Q; Yin, F
MLA Citation
Ashmeg, S, O'Daniel, J, Wu, Q, and Yin, F. "TH-E-BRB-11: Benchmarking Flattening-Filter Free Photons for IMRT/VMAT." June 2012.
Source
crossref
Published In
Medical physics
Volume
39
Issue
6Part31
Publish Date
2012
Start Page
4011
End Page
4011
DOI
10.1118/1.4736361

SU-E-T-70: A Protocol for Comprehensive Acceptance/Commissioning of Complex 3D QA Devices

Authors
O'Daniel, J; Ren, L; Yan, H; Yin, F
MLA Citation
O'Daniel, J, Ren, L, Yan, H, and Yin, F. "SU-E-T-70: A Protocol for Comprehensive Acceptance/Commissioning of Complex 3D QA Devices." June 2012.
Source
crossref
Published In
Medical physics
Volume
39
Issue
6Part10
Publish Date
2012
Start Page
3718
End Page
3718
DOI
10.1118/1.4735126

SU-E-T-381: Experimental Measurements of 3D Dose Distribution for a Moving Target Treated with IMRT and VMAT

Authors
Yan, H; Thomas, A; Oldham, M; Yin, F
MLA Citation
Yan, H, Thomas, A, Oldham, M, and Yin, F. "SU-E-T-381: Experimental Measurements of 3D Dose Distribution for a Moving Target Treated with IMRT and VMAT." June 2012.
Source
crossref
Published In
Medical physics
Volume
39
Issue
6Part15
Publish Date
2012
Start Page
3792
End Page
3792
DOI
10.1118/1.4735468

Stereotactic radiotherapy for malignancies involving the trigeminal and facial nerves.

Involvement of a cranial nerve caries a poor prognosis for many malignancies. Recurrent or residual disease in the trigeminal or facial nerve after primary therapy poses a challenge due to the location of the nerve in the skull base, the proximity to the brain, brainstem, cavernous sinus, and optic apparatus and the resulting complex geometry. Surgical resection caries a high risk of morbidity and is often not an option for these patients. Stereotactic radiosurgery and radiotherapy are potential treatment options for patients with cancer involving the trigeminal or facial nerve. These techniques can deliver high doses of radiation to complex volumes while sparing adjacent critical structures. In the current study, seven cases of cancer involving the trigeminal or facial nerve are presented. These patients had unresectable recurrent or residual disease after definitive local therapy. Each patient was treated with stereotactic radiation therapy using a linear accelerator based system. A multidisciplinary approach including neuroradiology and surgical oncology was used to delineate target volumes. Treatment was well tolerated with no acute grade 3 or higher toxicity. One patient who was reirradiated experienced cerebral radionecrosis with mild symptoms. Four of the seven patients treated had no evidence of disease after a median follow up of 12 months (range 2-24 months). A dosimetric analysis was performed to compare intensity modulated fractionated stereotactic radiation therapy (IM-FSRT) to a 3D conformal technique. The dose to 90% (D90) of the brainstem was lower with the IM-FSRT plan by a mean of 13.5 Gy. The D95 to the ipsilateral optic nerve was also reduced with IM-FSRT by 12.2 Gy and the D95 for the optic chiasm was lower with FSRT by 16.3 Gy. Treatment of malignancies involving a cranial nerve requires a multidisciplinary approach. Use of an IM-FSRT technique with a micro-multileaf collimator resulted in a lower dose to the brainstem, optic nerves and chiasm for each case examined.

Authors
Cuneo, KC; Zagar, TM; Brizel, DM; Yoo, DS; Hoang, JK; Chang, Z; Wang, Z; Yin, FF; Das, SK; Green, S; Ready, N; Bhatti, MT; Kaylie, DM; Becker, A; Sampson, JH; Kirkpatrick, JP
MLA Citation
Cuneo, KC, Zagar, TM, Brizel, DM, Yoo, DS, Hoang, JK, Chang, Z, Wang, Z, Yin, FF, Das, SK, Green, S, Ready, N, Bhatti, MT, Kaylie, DM, Becker, A, Sampson, JH, and Kirkpatrick, JP. "Stereotactic radiotherapy for malignancies involving the trigeminal and facial nerves." Technol Cancer Res Treat 11.3 (June 2012): 221-228.
PMID
22468993
Source
pubmed
Published In
Technology in cancer research & treatment
Volume
11
Issue
3
Publish Date
2012
Start Page
221
End Page
228
DOI
10.7785/tcrt.2012.500290

Verification of 4D Dose Delivery Using 4D Digital Human Phantom

Authors
Zhang, F; Qin, Y; Segars, W; Yin, F; Cai, J
MLA Citation
Zhang, F, Qin, Y, Segars, W, Yin, F, and Cai, J. "Verification of 4D Dose Delivery Using 4D Digital Human Phantom." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3859
End Page
3859

Adaptive Stereotactic-Body Radiation Therapy (SBRT) Planning for Lung Cancer

Authors
Qin, Y; Zhang, F; Kelsey, C; Yoo, D; Yin, F; Cai, J
MLA Citation
Qin, Y, Zhang, F, Kelsey, C, Yoo, D, Yin, F, and Cai, J. "Adaptive Stereotactic-Body Radiation Therapy (SBRT) Planning for Lung Cancer." June 2012.
Website
http://hdl.handle.net/10161/7295
PMID
23790773
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3908
End Page
3908

A Simple Method to Minimize Uncertainty in ITV Delineation: Phantom Verification

Authors
Turner, K; Cai, J; Yin, F; Zhang, Y; Vergalasova, I
MLA Citation
Turner, K, Cai, J, Yin, F, Zhang, Y, and Vergalasova, I. "A Simple Method to Minimize Uncertainty in ITV Delineation: Phantom Verification." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3700
End Page
3701

Assessing Effects of Ion Collection Efficiency in Flattening Filter-Free (FFF) Beams On Three TrueBeam Machines

Authors
Chang, Z; Wu, Q; Adamson, J; Ren, L; Bowsher, J; Yan, H; Thomas, A; Yin, F
MLA Citation
Chang, Z, Wu, Q, Adamson, J, Ren, L, Bowsher, J, Yan, H, Thomas, A, and Yin, F. "Assessing Effects of Ion Collection Efficiency in Flattening Filter-Free (FFF) Beams On Three TrueBeam Machines." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3719
End Page
3719

Commissioning and Dosimetric Characteristics of TrueBeam System: Composite Data of Three TrueBeam Machines

Authors
Chang, Z; Wu, Q; Adamson, J; Ren, L; Bowsher, J; Yan, H; Thomas, A; Yin, F
MLA Citation
Chang, Z, Wu, Q, Adamson, J, Ren, L, Bowsher, J, Yan, H, Thomas, A, and Yin, F. "Commissioning and Dosimetric Characteristics of TrueBeam System: Composite Data of Three TrueBeam Machines." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3726
End Page
3726

SU-E-T-406: Online Image-Guidance for Prostate SBRT: Dosimetric Benefits and Margin Analysis.

To evaluate the dosimetric benefits of online image guidance during prostate stereotactic body radiotherapy (SBRT) and the potential on margin reduction.28 prostate SBRT patients were retrospectively studied, each treated with 37Gy in 5 fractions. RTOG recently opened a similar protocol (0938). During treatments, per-beam couch corrections were made based on the actual target motion provided by dynamic tracking with either Calypso or per-beam OBI imaging. Dosimetric benefits of online correction were evaluated by comparing delivered dose distributions with and without such correction. The dose distribution without correction was generated in the same treatment planning system by accumulating doses without online correction from the each beam and each fraction. Quantitative analyses include the dosimetric difference between delivered doses with and without correction; the correction magnitude and frequency; and the potential on margin reduction based on the margin recipe by Van Herk et al.(1) Delivery without online correction results in small reduction on target mean dose (0.03±0.05Gy), maximal dose (0.01±0.06Gy), and conformity index (<0.06). (2) Delivery without online correction has small impact on OAR dose: 26 out of 28 patients have <1%/1.5cc differences in V18.5Gy/V24Gy/V28Gy/V33Gy/V37Gy for both the bladder and the rectum. Maximal differences are 4cc of the bladder and 1.6cc of the rectum in mid-dose regions (V18.5Gy). (3) For femoral heads, <1cc/1Gy differences are observed in V20Gy/Dmean/D1cc.(4) Average number of couch corrections per fraction is 0.49. The magnitudes are: (-0.2±2)mm vertically, (-0.1±2.1)mm longitudinally, and (-0.2±1.4)mm laterally. (5) Margin determined by actual target motion in this patient population is 2.5mm isotropic.For both target coverage and OAR sparing, overall small benefit is seen from per-beam couch correction under dynamic tracking. The target motion between beams is small and random, and indicates a population-based margin size of 2.5mm.

Authors
Li, T; Yuan, L; Lee, W; Yin, F; Wu, QJ
MLA Citation
Li, T, Yuan, L, Lee, W, Yin, F, and Wu, QJ. "SU-E-T-406: Online Image-Guidance for Prostate SBRT: Dosimetric Benefits and Margin Analysis." June 2012.
PMID
28517233
Source
epmc
Published In
Medical physics
Volume
39
Issue
6Part16
Publish Date
2012
Start Page
3798
DOI
10.1118/1.4735495

Treatment Delivery QA for Online Adaptive Radiation Therapy Based On Dynamic Machine Information (DMI): A Feasibility Study

Authors
Li, T; Yuan, L; Wu, Q; Yin, F; Wu, QJ
MLA Citation
Li, T, Yuan, L, Wu, Q, Yin, F, and Wu, QJ. "Treatment Delivery QA for Online Adaptive Radiation Therapy Based On Dynamic Machine Information (DMI): A Feasibility Study." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3867
End Page
3868

Individualized Trade-Off of Dose Coverage and Sparing in IMRT Planning

Authors
Yuan, L; Ge, Y; Li, T; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Li, T, Yin, F, and Wu, QJ. "Individualized Trade-Off of Dose Coverage and Sparing in IMRT Planning." June 2012.
PMID
28517546
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3850
End Page
3850

Modeling Inter-Patient Variation of Organ-At-Risk Sparing in IMRT Plans: An Evidence-Based Plan Quality Evaluation

Authors
Yuan, L; Ge, Y; Li, T; Yin, F; Wu, QJ
MLA Citation
Yuan, L, Ge, Y, Li, T, Yin, F, and Wu, QJ. "Modeling Inter-Patient Variation of Organ-At-Risk Sparing in IMRT Plans: An Evidence-Based Plan Quality Evaluation." June 2012.
PMID
28518274
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3868
End Page
3868

Contrast-To-Noise Ratio (CNR) Enhancement and Lag Correction in Cone Beam CT (CBCT) Using a Synchronized-MOving-Grid (SMOG) System

Authors
Ren, L; Jin, J; Yin, F
MLA Citation
Ren, L, Jin, J, and Yin, F. "Contrast-To-Noise Ratio (CNR) Enhancement and Lag Correction in Cone Beam CT (CBCT) Using a Synchronized-MOving-Grid (SMOG) System." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3890
End Page
3891

A Protocol for Comprehensive Acceptance/Commissioning of Complex 3D QA Devices

Authors
O'Daniel, J; Ren, L; Yan, H; Yin, F
MLA Citation
O'Daniel, J, Ren, L, Yan, H, and Yin, F. "A Protocol for Comprehensive Acceptance/Commissioning of Complex 3D QA Devices." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3718
End Page
3718

Benchmarking Flattening-Filter Free Photons for IMRT/VMAT

Authors
Ashmeg, S; O'Daniel, J; Wu, Q; Yin, F
MLA Citation
Ashmeg, S, O'Daniel, J, Wu, Q, and Yin, F. "Benchmarking Flattening-Filter Free Photons for IMRT/VMAT." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
4011
End Page
4011

Target localization using scanner-acquired SPECT data.

Target localization using single photon emission computed tomography (SPECT) and planar imaging is being investigated for guiding radiation therapy delivery. Previous studies on SPECT-based localization have used computer-simulated or hybrid images with simulated tumors embedded in disease-free patient images where the tumor position is known and localization can be calculated directly. In the current study, localization was studied using scanner-acquired images. Five fillable spheres were placed in a whole body phantom. Sphere-to-background 99mTc radioactivity was 6:1. Ten independent SPECT scans were acquired with a Trionix Triad scanner using three detector trajectories: left lateral 180°, 360°, and right lateral 180°. Scan time was equivalent to 4.5 min. Images were reconstructed with and without attenuation correction. True target locations were estimated from 12 hr SPECT and CT images. From the 12 hr SPECT scan, 45 sets of orthogonal planar images were used to assess target localization; total acquisition time per set was equivalent to 4.5min. A numerical observer localized the center of the targets in the 4.5 min SPECT and planar images. SPECT-based localization errors were compared for the different detector trajectories. Across the four peripheral spheres, and using optimal iteration numbers and postreconstruction smoothing, means and standard deviations in localization errors were 0.90 ± 0.25 mm for proximal 180° trajectories, 1.31 ± 0.51 mm for 360° orbits, and 3.93 ± 1.48 mm for distal 180° trajectories. This rank order in localization performance is predicted by target attenuation and distance from the target to the collimator. For the targets with mean localization errors < 2 mm, attenuation correction reduced localization errors by 0.15 mm on average. The improvement from attenuation correction was 1.0 mm on average for the more poorly localized targets. Attenuation correction typically reduced localization errors, but for well-localized targets, the detector trajectory generally had a larger effect. Localization performance was found to be robust to iteration number and smoothing. Localization was generally worse using planar images as compared with proximal 180° and 360° SPECT scans. Using a proximal detector trajectory and attenuation correction, localization errors were within 2 mm for the three superficial targets, thus supporting the current role in biopsy and surgery, and demonstrating the potential for SPECT imaging inside radiation therapy treatment rooms.

Authors
Roper, JR; Bowsher, JE; Wilson, JM; Turkington, TG; Yin, F-F
MLA Citation
Roper, JR, Bowsher, JE, Wilson, JM, Turkington, TG, and Yin, F-F. "Target localization using scanner-acquired SPECT data. (Published online)" J Appl Clin Med Phys 13.3 (May 10, 2012): 3724-.
PMID
22584168
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
13
Issue
3
Publish Date
2012
Start Page
3724

Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT.

PURPOSE: To determine whether there is a CT dataset may be more favorable for planning and dose calculation by comparing dosimetric characteristics between treatment plans calculated using free breathing (FB), maximum and average intensity projection (MIP and AIP, respectively) CTs for lung cancer patients receiving stereotactic body radiation therapy (SBRT). METHODS: Twenty lung cancer SBRT patients, treated on a linac with 2.5 mm width multileaf-collimator (MLC), were analyzed retrospectively. Both FB helical and four-dimensional CT scans were acquired for each patient. Internal target volume (ITV) was delineated based on MIP CTs and modified based on both ten-phase datasets and FB CTs. Planning target volume (PTV) was then determined by adding additional setup margin to ITV. The PTVs and beams in the optimized treatment plan based on FB CTs were copied to MIP and AIP CTs, with the same isocenters, MLC patterns and monitor units. Mean effective depth (MED) of beams, and some dosimetric parameters for both PTVs and most important organ at risk (OAR), lung minus PTV, were compared between any two datasets using two-tail paired t test. RESULTS: The MEDs in FB and AIP plans were similar but significantly smaller (Ps < 0.001) than that in MIP plans. Minimum dose, mean dose, dose covering at least 90% and 95% of PTVs in MIP plans were slightly higher than two other plans (Ps < 0.008). The absolute volume of lung minus PTV receiving greater than 5, 10, and 20 Gy in MIP plans were significantly smaller than those in both FB and AIP plans (Ps < 0.008). Conformity index for FB plans showed a small but statistically significantly higher. CONCLUSIONS: Dosimetric characteristics of AIP plans are similar to those of FB plans. Slightly better target volume coverage and significantly lower low-dose region (≤30 Gy) in lung was observed in MIP plans. The decrease in low-dose region in lung was mainly caused by the change of lung volume contoured on two datasets rather than the differences of dose distribution between AIP and MIP plans. Compare with AIP datasets, FB datasets were more prone to significant image artifacts and MIP datasets may overestimate or underestimate the target volume when the target is closer to the denser tissue, so AIP seems favorable for planning and dose calculation for lung SBRT.

Authors
Tian, Y; Wang, Z; Ge, H; Zhang, T; Cai, J; Kelsey, C; Yoo, D; Yin, F-F
MLA Citation
Tian, Y, Wang, Z, Ge, H, Zhang, T, Cai, J, Kelsey, C, Yoo, D, and Yin, F-F. "Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT." Med Phys 39.5 (May 2012): 2754-2760.
PMID
22559646
Source
pubmed
Published In
Medical physics
Volume
39
Issue
5
Publish Date
2012
Start Page
2754
End Page
2760
DOI
10.1118/1.4705353

Comparison of 3D conformal breast radiation treatment plans using the anisotropic analytical algorithm and pencil beam convolution algorithm.

PURPOSE: To investigate (1) dosimetric differences between plans calculated using the anisotropic analytical algorithm (AAA) and pencil beam convolution (PBC) algorithm, (2) the plan quality achieved using AAA compared to PBC based on dosimetric parameters and (3) discrepancies with an independent MU verification calculation for breast treatment planning. MATERIALS AND METHODS: This study included 10 lumpectomy (Group I) and 10 mastectomy (Group II) cases. Target volumes were defined as breast for Group I and chest-wall for Group II based on the isodose distribution of PBC plans in order to evaluate plans. All plans were initially calculated with PBC. For study aim (1), plans were re-calculated using AAA with the same monitor units (MUs). For study aim (2), plans were calculated using AAA with modifications of wedges, subfields and beam weightings from the original plans to achieve optimal coverage. For study aim (3), independent MU verification was performed. A 3% difference between primary MUs and verification MUs was considered an action level. RESULTS: (1) Plans using PBC overestimate the dose to the target volume compared to plans using AAA (Group I V(95%)=90.4%:84.4%; Group II V(95%)=83.0%:74.5%; PBC:AAA). (2) The new plans using AAA achieved similar target coverage to the original PBC plans based on dose-volume histograms (DVHs). Yet, the high-dose volume (V(105%)) was significantly larger in AAA plans than PBC plans for Group II (V(105%)=19.5%:24.0%). For both groups, there was a significant increase in the ipsilateral lung volume receiving low dose with AAA plans (Group I V(5 Gy)=23.6%:39.9%; Group II V(5 Gy)=21.2%:33.6%). Isodose distributions of AAA plans displayed insufficient coverage in the superior area. (3) In Group I, all PBC cases passed MU verification versus 30% of AAA cases. In Group II, 80% of PBC plans versus 65% of AAA plans were within the action level. CONCLUSIONS: Plans using AAA calculation can achieve a similar level of target coverage based on DVH as PBC calculation. Nevertheless, the dose distribution shows insufficient coverage in the superior area with AAA plans compared to PBC plans. The lung volume receiving the low-dose (i.e. 5 Gy) is larger and the dose to the skin is greater in AAA plans than PBC plans. Compared with PBC calculation, a larger tolerance in discrepancy between AAA and independent MU verification should be allowed to account for the inadequate heterogeneity corrections in the latter.

Authors
Yoo, S; Wu, Q; O'Daniel, J; Horton, J; Yin, F-F
MLA Citation
Yoo, S, Wu, Q, O'Daniel, J, Horton, J, and Yin, F-F. "Comparison of 3D conformal breast radiation treatment plans using the anisotropic analytical algorithm and pencil beam convolution algorithm." Radiother Oncol 103.2 (May 2012): 172-177.
PMID
22349127
Source
pubmed
Published In
Radiotherapy and Oncology
Volume
103
Issue
2
Publish Date
2012
Start Page
172
End Page
177
DOI
10.1016/j.radonc.2012.01.010

Volumetric-modulated arc therapy: effective and efficient end-to-end patient-specific quality assurance.

PURPOSE: To explore an effective and efficient end-to-end patient-specific quality-assurance (QA) protocol for volumetric modulated arc radiotherapy (VMAT) and to evaluate the suitability of a stationary radiotherapy QA device (two-dimensional [2D] ion chamber array) for VMAT QA. METHODS AND MATERIALS: Three methods were used to analyze 39 VMAT treatment plans for brain, spine, and prostate: ion chamber (one-dimensional absolute, n = 39), film (2D relative, coronal/sagittal, n = 8), and 2D ion chamber array (ICA, 2D absolute, coronal/sagittal, n = 39) measurements. All measurements were compared with the treatment planning system dose calculation either via gamma analysis (3%, 3- to 4-mm distance-to-agreement criteria) or absolute point dose comparison. The film and ion chamber results were similarly compared with the ICA measurements. RESULTS: Absolute point dose measurements agreed well with treatment planning system computed doses (ion chamber: median deviation, 1.2%, range, -0.6% to 3.3%; ICA: median deviation, 0.6%, range, -1.8% to 2.9%). The relative 2D dose measurements also showed good agreement with computed doses (>93% of pixels in all films passing gamma, >90% of pixels in all ICA measurements passing gamma). The ICA relative dose results were highly similar to those of film (>90% of pixels passing gamma). The coronal and sagittal ICA measurements were statistically indistinguishable by the paired t test with a hypothesized mean difference of 0.1%. The ion chamber and ICA absolute dose measurements showed a similar trend but had disparities of 2-3% in 18% of plans. CONCLUSIONS: After validating the new VMAT implementation with ion chamber, film, and ICA, we were able to maintain an effective yet efficient patient-specific VMAT QA protocol by reducing from five (ion chamber, film, and ICA) to two measurements (ion chamber and single ICA) per plan. The ICA (Matrixx®, IBA Dosimetry) was validated for VMAT QA, but ion chamber measurements are recommended for absolute dose comparison until future developments correct the ICA angular dependence.

Authors
O'Daniel, J; Das, S; Wu, QJ; Yin, F-F
MLA Citation
O'Daniel, J, Das, S, Wu, QJ, and Yin, F-F. "Volumetric-modulated arc therapy: effective and efficient end-to-end patient-specific quality assurance." Int J Radiat Oncol Biol Phys 82.5 (April 1, 2012): 1567-1574.
PMID
21470797
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
82
Issue
5
Publish Date
2012
Start Page
1567
End Page
1574
DOI
10.1016/j.ijrobp.2011.01.018

Development and clinical evaluation of a three-dimensional cone-beam computed tomography estimation method using a deformation field map.

PURPOSE: To develop a three-dimensional (3D) cone-beam computed tomography (CBCT) estimation method using a deformation field map, and to evaluate and optimize the efficiency and accuracy of the method for use in the clinical setting. METHODS AND MATERIALS: We propose a method to estimate patient CBCT images using prior information and a deformation model. Patients' previous CBCT data are used as the prior information, and the new CBCT volume to be estimated is considered as a deformation of the prior image volume. The deformation field map is solved by minimizing deformation energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. This method was implemented in 3D form using hardware acceleration and multi-resolution scheme, and it was evaluated for different scan angles, projection numbers, and scan directions using liver, lung, and prostate cancer patient data. The accuracy of the estimation was evaluated by comparing the organ volume difference and the similarity between estimated CBCT and the CBCT reconstructed from fully sampled projections. RESULTS: Results showed that scan direction and number of projections do not have significant effects on the CBCT estimation accuracy. The total scan angle is the dominant factor affecting the accuracy of the CBCT estimation algorithm. Larger scan angles yield better estimation accuracy than smaller scan angles. Lung cancer patient data showed that the estimation error of the 3D lung tumor volume was reduced from 13.3% to 4.3% when the scan angle was increased from 60° to 360° using 57 projections. CONCLUSIONS: The proposed estimation method is applicable for 3D DTS, 3D CBCT, four-dimensional CBCT, and four-dimensional DTS image estimation. This method has the potential for significantly reducing the imaging dose and improving the image quality by removing the organ distortion artifacts and streak artifacts shown in images reconstructed by the conventional Feldkamp-Davis-Kress (FDK) algorithm.

Authors
Ren, L; Chetty, IJ; Zhang, J; Jin, J-Y; Wu, QJ; Yan, H; Brizel, DM; Lee, WR; Movsas, B; Yin, F-F
MLA Citation
Ren, L, Chetty, IJ, Zhang, J, Jin, J-Y, Wu, QJ, Yan, H, Brizel, DM, Lee, WR, Movsas, B, and Yin, F-F. "Development and clinical evaluation of a three-dimensional cone-beam computed tomography estimation method using a deformation field map." Int J Radiat Oncol Biol Phys 82.5 (April 1, 2012): 1584-1593.
PMID
21477945
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
82
Issue
5
Publish Date
2012
Start Page
1584
End Page
1593
DOI
10.1016/j.ijrobp.2011.02.002

Accelerating phase contrast MR angiography by simplified skipped phase encoding and edge deghosting with array coil enhancement.

PURPOSE: The aim of this work is to investigate the feasibility of accelerating phase contrast magnetic resonance angiography (PC-MRA) by the fast imaging method of simplified skipped phase encoding and edge deghosting with array coil enhancement (S-SPEED-ACE). METHODS: The parallel imaging method of skipped phase encoding and edge deghosting with array coil enhancement (SPEED-ACE) is simplified for imaging sparse objects like phase contrast MRA. This approach is termed S-SPEED-ACE in which k-space is sparsely sampled with skipped phase encoding at every Nth step using multiple receiver coils simultaneously. The sampled data are then Fourier transformed into a set of ghosted images, each with N-fold aliasing ghosts. Given signal sparseness of MRA, the ghosted images are modeled with a single-layer structure, in which the most dominant ghost within the potentially overlapped ghosts at each pixel is selected to represent the signal of that pixel. The single-layer model is analogous to that used in maximum-intensity-projection (MIP) that selects only the brightest signal even when there are overlapped vessels. With an algorithm based on a least-square-error solution, a deghosted image is obtained, along with a residual map for quality control. In this way, S-SPEED-ACE partially samples k-space using multiple receiver coils in parallel, and yields a deghosted image with an acceleration factor of N. Without full central k-space sampling and differential filtering, S-SPEED-ACE achieves further scan time reduction with a more straightforward reconstruction. In this work, S-SPEED-ACE is demonstrated to accelerate a computer simulated PC-MRA and a real human 3D PC-MRA, which was acquired using a clinical 1.5 T scanner on a healthy volunteer. RESULTS: Images are reconstructed by S-SPEED-ACE to achieve an undersampling factor of up to 8.3 with four receiver coils. The reconstructed images generally have comparable quality as that of the reference images reconstructed from full k-space data. Maximum-intensity-projection images generated from the reconstructed images also demonstrated to be consistent as those from the reference images. CONCLUSIONS: By taking advantage of signal sparsity naturally existing in the data, SPEED-ACE was simplified and its efficiency was improved. The feasibility of the proposed S-SPEED-ACE is demonstrated in this work with simulated sampling of an actual 3D head PC-MRA scan.

Authors
Chang, Z; Xiang, Q-S; Shen, H; Ji, J; Yin, F-F
MLA Citation
Chang, Z, Xiang, Q-S, Shen, H, Ji, J, and Yin, F-F. "Accelerating phase contrast MR angiography by simplified skipped phase encoding and edge deghosting with array coil enhancement." Med Phys 39.3 (March 2012): 1247-1252.
PMID
22380356
Source
pubmed
Published In
Medical physics
Volume
39
Issue
3
Publish Date
2012
Start Page
1247
End Page
1252
DOI
10.1118/1.3682000

A novel technique for markerless, self-sorted 4D-CBCT: feasibility study.

PURPOSE: Four-dimensional CBCT (4D-CBCT) imaging in the treatment room can provide verification of moving targets, facilitating the potential for margin reduction and consequent dose escalation. Reconstruction of 4D-CBCT images requires correlation of respiratory phase with projection acquisition, which is often achieved with external surrogate measures of respiration. However, external measures may not be a direct representation of the motion of the internal anatomy and it is therefore the aim of this work to develop a novel technique for markerless, self-sorted 4D-CBCT reconstruction. METHODS: A novel 4D-CBCT reconstruction technique based on the principles of Fourier transform (FT) theory was investigated for markerless extraction of respiratory phase directly from projection data. In this FT technique, both phase information (FT-phase) and magnitude information (FT-magnitude) were separately implemented in order to discern projections corresponding to peak inspiration, which then facilitated the proceeding sort and bin processes involved in retrospective 4D image reconstruction. In order to quantitatively evaluate the accuracy of the Fourier methods, peak-inspiration projections identified each by FT-phase and FT-magnitude were compared to those manually identified by visual tracking of structures. The average phase difference as assigned by each method vs the manual technique was calculated per projection dataset. The percentage of projections that were assigned within 10% phase of each other was also computed. Both Fourier methods were tested on two phantom datasets, programmed to exhibit sinusoidal respiratory cycles of 2.0 cm in amplitude with respiratory cycle lengths of 3 and 6 s, respectively. Additionally, three sets of patient projections were studied. All of the data were previously acquired at slow-gantry speeds ranging between 0.6°/s and 0.7°/s over a 200° rotation. Ten phase bins with 10% phase windows were selected for 4D-CBCT reconstruction of one phantom and one patient case for visual and quantitative comparison. Line profiles were plotted for the 0% and 50% phase images as reconstructed by the manual technique and each of the Fourier methods. RESULTS: As compared with the manual technique, the FT-phase method resulted in average phase differences of 1.8% for the phantom with the 3 s respiratory cycle, 3.9% for the phantom with the 6 s respiratory cycle, 2.9% for patient 1, 5.0% for patient 2, and 3.8% for patient 3. For the FT-magnitude method, these numbers were 2.1%, 4.0%, 2.9%, 5.3%, and 3.5%, respectively. The percentage of projections that were assigned within 10% phase by the FT-phase method as compared to the manual technique for the five datasets were 100.0%, 100.0%, 97.6%, 93.4%, and 94.1%, respectively, whereas for the FT-magnitude method these percentages were 98.1%, 92.3%, 98.7%, 87.3%, and 95.7%. Reconstructed 4D phase images for both the phantom and patient case were visually and quantitatively equivalent between each of the Fourier methods vs the manual technique. CONCLUSIONS: A novel technique employing the basics of Fourier transform theory was investigated and demonstrated to be feasible in achieving markerless, self-sorted 4D-CBCT reconstruction.

Authors
Vergalasova, I; Cai, J; Yin, F-F
MLA Citation
Vergalasova, I, Cai, J, and Yin, F-F. "A novel technique for markerless, self-sorted 4D-CBCT: feasibility study." Med Phys 39.3 (March 2012): 1442-1451.
PMID
22380377
Source
pubmed
Published In
Medical physics
Volume
39
Issue
3
Publish Date
2012
Start Page
1442
End Page
1451
DOI
10.1118/1.3685443

On-Board Digital Tomosynthesis: An Emerging New Technology for IGRT

Authors
Wu, QJ; Godfrey, DJ; Ren, L; Yoo, S; Yin, F
MLA Citation
Wu, QJ, Godfrey, DJ, Ren, L, Yoo, S, and Yin, F. "On-Board Digital Tomosynthesis: An Emerging New Technology for IGRT." Image-Guided Radiation Therapy. Ed. D Bourland. CRC Press, February 22, 2012. (Chapter)
Source
manual
Publish Date
2012

Lipiodol: a potential direct surrogate for cone-beam computed tomography image guidance in radiotherapy of liver tumor.

PURPOSE: To investigate the feasibility of using lipiodol as a direct surrogate for target localization using cone-beam CT (CBCT) image guidance in radiotherapy (RT) of patients with unresectable liver tumors after transarterial chemoembolization. METHODS AND MATERIALS: Forty-six patients with an unresectable solitary liver tumor were enrolled for RT using active breathing control (ABC) and CBCT image guidance after transarterial chemoembolization. Each patient had pre- and posttreatment CBCT in the first 10 fractions of treatment. Lipiodol retention was evaluated using daily CBCT scans, and volume of lipiodol retention in the liver was calculated and compared between planning CT and post-RT CT. Influence of lipiodol on dosimetry was evaluated by measuring doses using an ion chamber with and without the presence of lipiodol. Margin analysis was performed on the basis of both inter- and intrafractional target localization errors. RESULTS: Twenty-eight patients successfully completed the study. The shape and size of lipiodol retention did not vary substantially during the course of treatment. The mean Dice similarity coefficient for the lipiodol volume in pretreatment CT and that in posttreatment CT was 0.836 (range, 0.817-0.885). The maximum change (ratio of the lipiodol volume in pretreatment CT to that in posttreatment CT) was 1.045. The mean dose changes with the presence of <10 mL lipiodol were -1.44% and 0.13% for 6 MV and 15 MV, respectively. With ABC and online CBCT image guidance, clinical target volume-planning target volume margins were determined to be 2.5 mm in the mediolateral direction, 2.9 mm in the anteroposterior direction, and 4.0 mm in the craniocaudal direction. CONCLUSIONS: Lipiodol could be used as a direct surrogate for CBCT image guidance to improve the localization accuracy for RT of liver tumors. Combination of ABC and CBCT image guidance with lipiodol can potentially reduce the clinical target volume-planning target volume margin.

Authors
Yue, J; Sun, X; Cai, J; Yin, F-F; Yin, Y; Zhu, J; Lu, J; Liu, T; Yu, J; Shi, X; Song, J
MLA Citation
Yue, J, Sun, X, Cai, J, Yin, F-F, Yin, Y, Zhu, J, Lu, J, Liu, T, Yu, J, Shi, X, and Song, J. "Lipiodol: a potential direct surrogate for cone-beam computed tomography image guidance in radiotherapy of liver tumor." Int J Radiat Oncol Biol Phys 82.2 (February 1, 2012): 834-841.
PMID
21377291
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
82
Issue
2
Publish Date
2012
Start Page
834
End Page
841
DOI
10.1016/j.ijrobp.2010.12.050

DOSE DEPENDENCE OF RADIATION-INDUCED ERECTILE DYSFUNCTION IN AN ANIMAL MODEL

Authors
Koontz, B; Kimura, M; Yan, H; Zodda, A; Broadwater, G; Donatucci, C; Yin, F-F; Vujaskovic, Z
MLA Citation
Koontz, B, Kimura, M, Yan, H, Zodda, A, Broadwater, G, Donatucci, C, Yin, F-F, and Vujaskovic, Z. "DOSE DEPENDENCE OF RADIATION-INDUCED ERECTILE DYSFUNCTION IN AN ANIMAL MODEL." JOURNAL OF SEXUAL MEDICINE 9 (February 2012): 4-4.
Source
wos-lite
Published In
The Journal of Sexual Medicine
Volume
9
Publish Date
2012
Start Page
4
End Page
4

Imaging system QA of a medical accelerator, Novalis Tx, for IGRT per TG 142: Our 1 year experience

American Association of Physicists in Medicine (AAPM) task group (TG) 142 has recently published a report to update recommendations of the AAPM TG 40 report and add new recommendations concerning medical accelerators in the era of image-guided radiation therapy (IGRT). The recommendations of AAPM TG 142 on IGRT are timely. In our institute, we established a comprehensive imaging QA program on a medical accelerator based on AAPM TG 142 and implemented it successfully. In this paper, we share our one-year experience and performance evaluation of an OBI capable linear accelerator, Novalis Tx, per TG 142 guidelines.

Authors
Chang, Z; Bowsher, J; Cai, J; Yoo, S; Wang, Z; Adamson, J; Ren, L; Yin, F-F
MLA Citation
Chang, Z, Bowsher, J, Cai, J, Yoo, S, Wang, Z, Adamson, J, Ren, L, and Yin, F-F. "Imaging system QA of a medical accelerator, Novalis Tx, for IGRT per TG 142: Our 1 year experience." Journal of Applied Clinical Medical Physics 13.4 (2012): 113-140.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
13
Issue
4
Publish Date
2012
Start Page
113
End Page
140

Interleaved acquisition for cross scatter avoidance in dual cone-beam CT

Purpose: Cone-beam x-ray imaging with flat panel detectors is used for target localization in image guided radiation therapy. This imaging includes cone-beam computed tomography (CBCT) and planar imaging. Use of two orthogonal x-ray systems could reduce imaging time for CBCT, provide simultaneous orthogonal views in planar imaging, facilitate dual-energy methods, and be useful in alleviating cone-beam artifacts by providing two axially offset focal-spot trajectories. However, the potential advantages of a second cone-beam system come at the cost of cross scatter, i.e., scatter of photons originating from one tube into the noncorresponding detector. Herein, cross scatter is characterized for dual cone-beam imaging, and a method for avoiding cross scatter is proposed and evaluated. Methods: A prototype dual-source CBCT system has been developed that models the geometry of a gantry-mounted kV imaging device used in radiation therapy. Cross scatter was characterized from 70 to 145 kVp in projections and reconstructed images using this system and three cylindrical phantoms (15, 20, and 30 cm) with a common Catphan core. A novel strategy for avoiding cross scatter in dual CBCT was developed that utilized interleaved data acquisition on each imaging chain. Interleaving, while maintaining similar angular sampling, can be achieved by either doubling the data acquisition rate or, as presented herein, halving the rotation speed. Results: The ratio of cross scatter to the total detected signal was found to be as high as 0.59 in a 30 cm diameter phantom. The measured scatter-to-primary ratio in some cases exceeded 4. In the 30 cm phantom, reconstructed contrast was reduced across all ROIs by an average of 48.7 when cross scatter was present. These cross-scatter degradations were almost entirely avoided by the method of interleaved exposures. Conclusions: Cross scatter is substantial in dual cone-beam imaging, but its effects can be largely removed by interleaved acquisition, which can be achieved at the same angular sampling rate either by doubling the data acquisition rate or halving the rotation speed. © 2012 American Association of Physicists in Medicine.

Authors
Giles, W; Bowsher, J; Li, H; Yin, F-F
MLA Citation
Giles, W, Bowsher, J, Li, H, and Yin, F-F. "Interleaved acquisition for cross scatter avoidance in dual cone-beam CT." Medical Physics 39.12 (2012): 7719-7728.
PMID
23231319
Source
scival
Published In
Medical physics
Volume
39
Issue
12
Publish Date
2012
Start Page
7719
End Page
7728
DOI
10.1118/1.4768160

Target localization using scanner-acquired SPECT data

Target localization using single photon emission computed tomography (SPECT) and planar imaging is being investigated for guiding radiation therapy delivery. Previous studies on SPECT-based localization have used computer-simulated or hybrid images with simulated tumors embedded in disease-free patient images where the tumor position is known and localization can be calculated directly. In the current study, localization was studied using scanner-acquired images. Five fillable spheres were placed in a whole body phantom. Sphere-to-background 99mTc radioactivity was 6:1. Ten independent SPECT scans were acquired with a Trionix Triad scanner using three detector trajectories: left lateral 180°, 360°, and right lateral 180°. Scan time was equivalent to 4.5 min. Images were reconstructed with and without attenuation correction. True target locations were estimated from 12 hr SPECT and CT images. From the 12 hr SPECT scan, 45 sets of orthogonal planar images were used to assess target localization; total acquisition time per set was equivalent to 4.5min. A numerical observer localized the center of the targets in the 4.5 min SPECT and planar images. SPECT-based localization errors were compared for the different detector trajectories. Across the four peripheral spheres, and using optimal iteration numbers and postreconstruction smoothing, means and standard deviations in localization errors were 0.90 ± 0.25 mm for proximal 180° trajectories, 1.31 ± 0.51 mm for 360° orbits, and 3.93 ± 1.48 mm for distal 180° trajectories. This rank order in localization performance is predicted by target attenuation and distance from the target to the collimator. For the targets with mean localization errors < 2 mm, attenuation correction reduced localization errors by 0.15 mm on average. The improvement from attenuation correction was 1.0 mm on average for the more poorly localized targets. Attenuation correction typically reduced localization errors, but for well-localized targets, the detector trajectory generally had a larger effect. Localization performance was found to be robust to iteration number and smoothing. Localization was generally worse using planar images as compared with proximal 180° and 360° SPECT scans. Using a proximal detector trajectory and attenuation correction, localization errors were within 2 mm for the three superficial targets, thus supporting the current role in biopsy and surgery, and demonstrating the potential for SPECT imaging inside radiation therapy treatment rooms.

Authors
Roper, JR; Bowsher, JE; Wilson, JM; Turkington, TG; Yin, F-F
MLA Citation
Roper, JR, Bowsher, JE, Wilson, JM, Turkington, TG, and Yin, F-F. "Target localization using scanner-acquired SPECT data." Journal of Applied Clinical Medical Physics 13.3 (2012): 108-123.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
13
Issue
3
Publish Date
2012
Start Page
108
End Page
123

Development of a 4D dosimetry simulation system in radiotherapy

4D CT image sets are used to encode patient-organ motion and to calculate the dose delivered during each respiratory phase. The dose-per-phase is summarised to the total dose via deformable registration. The system incorporates the actual beam parameters and synchronises the beam motion (e.g., gantry/MLC motion of the DARC and MLC motion of the IMRT) to the patient's respiratory motion. Furthermore, this system incorporates different treatment techniques such as 3D conformal (3DCRT), dynamic arc (DARC), and Intensity-Modulated Radiation Therapy (IMRT), thus allows better understanding of organ motion effect on dose delivery, treatment techniques and corresponding optimal margins. Copyright © 2012 Inderscience Enterprises Ltd.

Authors
Wu, QJ; Thongphiew, D; Wang, Z; Willett, C; Marks, L; Yin, F-F
MLA Citation
Wu, QJ, Thongphiew, D, Wang, Z, Willett, C, Marks, L, and Yin, F-F. "Development of a 4D dosimetry simulation system in radiotherapy." International Journal of Biomedical Engineering and Technology 8.2-3 (2012): 230-244.
Source
scival
Published In
International Journal of Biomedical Engineering and Technology
Volume
8
Issue
2-3
Publish Date
2012
Start Page
230
End Page
244
DOI
10.1504/IJBET.2012.046088

Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: a feasibility study.

PURPOSE: Four-dimensional computed tomography (4D-CT) has been widely used in radiation therapy to assess patient-specific breathing motion for determining individual safety margins. However, it has two major drawbacks: low soft-tissue contrast and an excessive imaging dose to the patient. This research aimed to develop a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique to overcome these limitations. METHODS: The proposed 4D-MRI technique was achieved by continuously acquiring axial images throughout the breathing cycle using fast 2D cine-MR imaging, and then retrospectively sorting the images by respiratory phase. The key component of the technique was the use of body area (BA) of the axial MR images as an internal respiratory surrogate to extract the breathing signal. The validation of the BA surrogate was performed using 4D-CT images of 12 cancer patients by comparing the respiratory phases determined using the BA method to those determined clinically using the Real-time position management (RPM) system. The feasibility of the 4D-MRI technique was tested on a dynamic motion phantom, the 4D extended Cardiac Torso (XCAT) digital phantom, and two healthy human subjects. RESULTS: Respiratory phases determined from the BA matched closely to those determined from the RPM: mean (± SD) difference in phase: -3.9% (± 6.4%); mean (± SD) absolute difference in phase: 10.40% (± 3.3%); mean (± SD) correlation coefficient: 0.93 (± 0.04). In the motion phantom study, 4D-MRI clearly showed the sinusoidal motion of the phantom; image artifacts observed were minimal to none. Motion trajectories measured from 4D-MRI and 2D cine-MRI (used as a reference) matched excellently: the mean (± SD) absolute difference in motion amplitude: -0.3 (± 0.5) mm. In the 4D-XCAT phantom study, the simulated "4D-MRI" images showed good consistency with the original 4D-XCAT phantom images. The motion trajectory of the hypothesized "tumor" matched excellently between the two, with a mean (± SD) absolute difference in motion amplitude of 0.5 (± 0.4) mm. 4D-MRI was able to reveal the respiratory motion of internal organs in both human subjects; superior-inferior (SI) maximum motion of the left kidney of Subject #1 and the diaphragm of Subject #2 measured from 4D-MRI was 0.88 and 1.32 cm, respectively. CONCLUSIONS: Preliminary results of our study demonstrated the feasibility of a novel retrospective 4D-MRI technique that uses body area as a respiratory surrogate.

Authors
Cai, J; Chang, Z; Wang, Z; Paul Segars, W; Yin, F-F
MLA Citation
Cai, J, Chang, Z, Wang, Z, Paul Segars, W, and Yin, F-F. "Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: a feasibility study." Med Phys 38.12 (December 2011): 6384-6394.
PMID
22149822
Source
pubmed
Published In
Medical physics
Volume
38
Issue
12
Publish Date
2011
Start Page
6384
End Page
6394
DOI
10.1118/1.3658737

Contour based respiratory motion analysis for free breathing CT.

We propose a method to quantify superior-inferior (SI) motion of a rigid target using the 3D contour from free-breathing CT (FBCT). The technique utilizes similarity between 2D contours (Jaccard Index) and a population based density function for probability of motion amplitude, and is applicable both when the static target shape is and is not known beforehand. Simulations and phantom measurements showed that motion reconstruction is often feasible, with decreasing accuracy as discrepancy is introduced between assumed and actual static shape. When no static shape is used the analysis is most robust for slow scanning speeds relative to the motion period.

Authors
Adamson, J; Zhuang, T; Yin, F-F
MLA Citation
Adamson, J, Zhuang, T, and Yin, F-F. "Contour based respiratory motion analysis for free breathing CT." Comput Biol Med 41.10 (October 2011): 908-915.
PMID
21839991
Source
pubmed
Published In
Computers in Biology and Medicine
Volume
41
Issue
10
Publish Date
2011
Start Page
908
End Page
915
DOI
10.1016/j.compbiomed.2011.08.002

Radiation-induced erectile dysfunction using prostate-confined modern radiotherapy in a rat model.

INTRODUCTION: The mechanisms of radiation-induced erectile dysfunction (ED) are unclear, as clinical studies are limited, and previous animal models were based on wide-field irradiation, which does not model current radiotherapy (RT) techniques. AIMS: To perform functional and morphological analyses of erectile function (EF) utilizing image-guided stereotactic prostate-confined RT in a rat model. METHODS: Sixty young adult male rats aged 10-12 weeks old were divided into age-matched sham and RT groups. A single 20-Gy fraction to the prostate was delivered to RT animals. Penile bulb, shaft, and testes were excluded from treatment fields. MAIN OUTCOME MEASURES: Bioassay and intracavernous pressure (ICP) measurements were conducted at 2, 4, and 9 weeks following RT. Perfusion analysis of the corpora cavernosa (CC) was conducted using Hoechst injected prior to sacrifice. Penile shaft and cavernous nerve (CN) were evaluated by immunohistochemistry. Plasma testosterone level was analyzed using a testosterone enzyme-linked immunosorbent assay (ELISA) assay kit. RESULTS: Irradiated animals demonstrated statistically significant time-dependent functional impairment of EF by bioassay and ICP measurement from 4 weeks. Neuronal nitric oxide synthase (NOS) expression was decreased in CN by 4 weeks. In CC, expression levels of anti-alpha smooth muscle actin and endothelial NOS were significantly decreased at 9 weeks. In penile dorsal vessels, smooth muscle/collagen ratio was significantly decreased at 4 and 9 weeks. Additionally, Hoechst perfusion showed time-dependent decrease in CC of RT animals, whereas CD31 expression was not affected. No toxicities were noted; testosterone levels were similar in both groups. CONCLUSION: We demonstrated time-dependent ED following image-guided stereotactic RT. Our results imply that reduction of neuronal NOS expression in cavernous nerve could trigger consecutive reduction of smooth muscle content as well as blood perfusion in CC that resulted in corporal veno-occlusive dysfunction. Present study could be a cornerstone to future research that may bring comprehensive scientific understanding of radiation-induced ED.

Authors
Kimura, M; Yan, H; Rabbani, Z; Satoh, T; Baba, S; Yin, F-F; Polascik, TJ; Donatucci, CF; Vujaskovic, Z; Koontz, BF
MLA Citation
Kimura, M, Yan, H, Rabbani, Z, Satoh, T, Baba, S, Yin, F-F, Polascik, TJ, Donatucci, CF, Vujaskovic, Z, and Koontz, BF. "Radiation-induced erectile dysfunction using prostate-confined modern radiotherapy in a rat model." J Sex Med 8.8 (August 2011): 2215-2226.
PMID
21679303
Source
pubmed
Published In
The Journal of Sexual Medicine
Volume
8
Issue
8
Publish Date
2011
Start Page
2215
End Page
2226
DOI
10.1111/j.1743-6109.2011.02351.x

Potential underestimation of the internal target volume (ITV) from free-breathing CBCT.

PURPOSE: Localization prior to delivery of SBRT to free-breathing patients is performed by aligning the planning internal target volume (ITV) from 4DCT with an on-board free-breathing cone-beam CT (FB-CBCT) image. The FB-CBCT image is assumed to also generate an ITV that captures the full range of motion, due to the acquisition spanning multiple respiratory cycles. However, the ITV could potentially be underestimated when the ratio of time spent in inspiration versus time spent in expiration (I/E ratio) deviates from unity. Therefore, the aim of this study was to investigate the effect of variable I/E ratios on the FB ITV generated from a FB-CBCT scan. METHODS: This study employed both phantom and patient imaging data. For the phantom study, five periodic respiratory cycles were simulated with different I/E ratios. Six patient respiratory cycles with variable I/E ratios were also selected. All profiles were then programmed into a motion phantom for imaging and modified to exhibit three peak-to-peak motion amplitudes (0.5, 1.0, and 2.0 cm). Each profile was imaged using two spherical targets with 1.0 and 3.0 cm diameters. 2D projections were acquired with full gantry rotation of a kiloVoltage (kV) imager mounted onto the gantry of a modem linear accelerator. CBCT images were reconstructed from 2D projections using a standard filtered back-projection reconstruction algorithm. Quantitative analyses for the phantom study included computing the change in contrast along the direction of target motion as well as determining the area (which is proportional to the target volume) inside of the contour extracted using a Canny edge detector. For the patient study, projection data that were previously acquired under an investigational 4D CBCT slow-gantry imaging protocol were used to generate both FB-CBCT and 4D CBCT images. Volumes were then manually contoured from both datasets (using the same window and level) for quantitative comparison. RESULTS: The phantom study indicated a reduction in contrast at the inferior edge of the ITV (corresponding to inspiration) as the ratio decreased, for both simulated and patient respiratory cycles. For the simulated phantom respiratory cycles, the contrast reduction of the smallest I/E ratio was 27.6% for the largest target with the smallest amplitude and 89.7% for the smallest target with the largest amplitude. For patient respiratory cycles, these numbers were 22.3% and 94.0%, respectively. The extracted area from inside of the target contours showed a decreasing trend as the I/E ratio decreased. In the patient study, the FB-CBCT ITVs of both lung tumors studied were underestimated when compared with their corresponding 4D CBCT ITV. The underestimations found were 40.1% for the smaller tumor and 24.2% for the larger tumor. CONCLUSIONS: The ITV may be underestimated in a FB-CBCT image when a patient's respiratory pattern is characterized by a disparate length of time spent in inspiration versus expiration. Missing the full target motion information during on-board verification imaging may result in localization errors.

Authors
Vergalasova, I; Maurer, J; Yin, F-F
MLA Citation
Vergalasova, I, Maurer, J, and Yin, F-F. "Potential underestimation of the internal target volume (ITV) from free-breathing CBCT." Med Phys 38.8 (August 2011): 4689-4699.
PMID
21928643
Source
pubmed
Published In
Medical physics
Volume
38
Issue
8
Publish Date
2011
Start Page
4689
End Page
4699
DOI
10.1118/1.3613153

SU-C-214-06: Noise Power Properties of a Dual-Detector Cone-Beam CT System

Authors
Li, H; Giles, W; Roper, J; Bowsher, J; Yin, F
MLA Citation
Li, H, Giles, W, Roper, J, Bowsher, J, and Yin, F. "SU-C-214-06: Noise Power Properties of a Dual-Detector Cone-Beam CT System." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part2
Publish Date
2011
Start Page
3373
End Page
3373
DOI
10.1118/1.3611484

TU-E-BRC-08: Investigation of Anatomical Surrogate for 4DCT Imaging

Authors
Cai, J; Chang, Z; OˈDaniel, J; Yoo, S; Jian, Y; Ge, H; Yin, F
MLA Citation
Cai, J, Chang, Z, OˈDaniel, J, Yoo, S, Jian, Y, Ge, H, and Yin, F. "TU-E-BRC-08: Investigation of Anatomical Surrogate for 4DCT Imaging." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part29
Publish Date
2011
Start Page
3771
End Page
3771
DOI
10.1118/1.3613195

SU-E-I-29: A Prior Information Based Total-Variation Digital Tomosynthesis Reconstruction Algorithm

Authors
Jian, Y; Cai, J; Yin, F
MLA Citation
Jian, Y, Cai, J, and Yin, F. "SU-E-I-29: A Prior Information Based Total-Variation Digital Tomosynthesis Reconstruction Algorithm." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part4
Publish Date
2011
Start Page
3402
End Page
3402
DOI
10.1118/1.3611602

MO-D-214-01: 4D-MRI for Radiation Therapy of Moving Tumors

Authors
Yin, F; Biederer, J; Cai, J; Parikh, P
MLA Citation
Yin, F, Biederer, J, Cai, J, and Parikh, P. "MO-D-214-01: 4D-MRI for Radiation Therapy of Moving Tumors." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part26
Publish Date
2011
Start Page
3714
End Page
3715
DOI
10.1118/1.3612976

SU-E-T-123: Evaluation of Integrated Gating Systems on a Novalis Tx System Using Quantitative Motion Tracking Analyses and Efficient Time-Delay Measurements

Authors
Chang, Z; Liu, T; Cai, J; Chen, Q; Wang, Z; Yin, F
MLA Citation
Chang, Z, Liu, T, Cai, J, Chen, Q, Wang, Z, and Yin, F. "SU-E-T-123: Evaluation of Integrated Gating Systems on a Novalis Tx System Using Quantitative Motion Tracking Analyses and Efficient Time-Delay Measurements." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part12
Publish Date
2011
Start Page
3514
End Page
3514
DOI
10.1118/1.3612074

SU-F-BRA-10: A Novel Technique for Markerless Self-Sorted 4D-CBCT

Authors
Vergalasova, I; Cai, J; Yin, F
MLA Citation
Vergalasova, I, Cai, J, and Yin, F. "SU-F-BRA-10: A Novel Technique for Markerless Self-Sorted 4D-CBCT." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part25
Publish Date
2011
Start Page
3702
End Page
3702
DOI
10.1118/1.3612877

SU-E-T-99: A Patient Specific QA Protocol for Verification of 4D Dosimetry

Authors
Yin, F; Thomas, A; Yan, H; Vergalasova, I; Adamovics, J; Wu, Q; Oldham, M
MLA Citation
Yin, F, Thomas, A, Yan, H, Vergalasova, I, Adamovics, J, Wu, Q, and Oldham, M. "SU-E-T-99: A Patient Specific QA Protocol for Verification of 4D Dosimetry." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part11
Publish Date
2011
Start Page
3508
End Page
3508
DOI
10.1118/1.3612050

MO-D-BRC-01: Dosimetric Evaluation of a Novel Cone-Beam CT (CBCT) Estimation Method Using Prior Information for Lung Cancer Patient Treatment

Authors
Ren, L; Jin, J; Movsas, B; Yin, F; Chetty, I
MLA Citation
Ren, L, Jin, J, Movsas, B, Yin, F, and Chetty, I. "MO-D-BRC-01: Dosimetric Evaluation of a Novel Cone-Beam CT (CBCT) Estimation Method Using Prior Information for Lung Cancer Patient Treatment." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part26
Publish Date
2011
Start Page
3712
End Page
3712
DOI
10.1118/1.3612965

SU-E-T-860: Developing a Fast-Monotonic Descent (FMD) Algorithm for RapidArc Radiotherapy

Authors
Yan, H; Yin, F
MLA Citation
Yan, H, and Yin, F. "SU-E-T-860: Developing a Fast-Monotonic Descent (FMD) Algorithm for RapidArc Radiotherapy." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part24
Publish Date
2011
Start Page
3689
End Page
3689
DOI
10.1118/1.3612824

SU-E-T-854: Key Anatomical Factors Influencing OAR Dose-Volume Distribution in Prostate IMRT Plans

Authors
Yuan, L; Ge, Y; Li, T; Zhu, X; Yin, F; Wu, Q
MLA Citation
Yuan, L, Ge, Y, Li, T, Zhu, X, Yin, F, and Wu, Q. "SU-E-T-854: Key Anatomical Factors Influencing OAR Dose-Volume Distribution in Prostate IMRT Plans." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part24
Publish Date
2011
Start Page
3688
End Page
3688
DOI
10.1118/1.3612818

TH-E-BRB-05: Modeling the Correlation Between OAR Dose Sparing and Patientˈs Anatomy in Head and Neck IMRT

Authors
Yuan, L; Ge, Y; Li, T; Zhu, X; Yin, F; Wu, Q
MLA Citation
Yuan, L, Ge, Y, Li, T, Zhu, X, Yin, F, and Wu, Q. "TH-E-BRB-05: Modeling the Correlation Between OAR Dose Sparing and Patientˈs Anatomy in Head and Neck IMRT." June 2011.
Source
crossref
Published In
Medical physics
Volume
38
Issue
6Part35
Publish Date
2011
Start Page
3867
End Page
3867
DOI
10.1118/1.3613562

Adaptive radiation therapy: technical components and clinical applications.

In current standard radiation therapy process, patient anatomy is represented by the snapshot of computed tomographic images at the simulation for treatment planning. However, patient anatomy during the treatment course is not static, and the changes can be in the order of centimeters. The goal of the adaptive radiation therapy (ART) is to measure and account these variations in the treatment process, so that the optimal planned dose distribution is the same as the final delivered dose distribution. The field of the ART is rapidly evolving. The implementation of the ART principle is built on technical components in 3 main areas: image guidance, dose verification, and plan adaptation. The purpose of this review was to present different ART methods currently developed and used by different investigators.

Authors
Wu, QJ; Li, T; Wu, Q; Yin, F-F
MLA Citation
Wu, QJ, Li, T, Wu, Q, and Yin, F-F. "Adaptive radiation therapy: technical components and clinical applications." Cancer J 17.3 (May 2011): 182-189. (Review)
PMID
21610472
Source
pubmed
Published In
Cancer Journal
Volume
17
Issue
3
Publish Date
2011
Start Page
182
End Page
189
DOI
10.1097/PPO.0b013e31821da9d8

Evaluation of integrated respiratory gating systems on a Novalis Tx system.

The purpose of this study was to investigate the accuracy of motion tracking and radiation delivery control of integrated gating systems on a Novalis Tx system. The study was performed on a Novalis Tx system, which is equipped with Varian Real-time Position Management (RPM) system, and BrainLAB ExacTrac gating systems. In this study, the two systems were assessed on accuracy of both motion tracking and radiation delivery control. To evaluate motion tracking, two artificial motion profiles and five patients' respiratory profiles were used. The motion trajectories acquired by the two gating systems were compared against the references. To assess radiation delivery control, time delays were measured using a single-exposure method. More specifically, radiation is delivered with a 4 mm diameter cone within the phase range of 10%-45% for the BrainLAB ExacTrac system, and within the phase range of 0%-25% for the Varian RPM system during expiration, each for three times. Radiochromic films were used to record the radiation exposures and to calculate the time delays. In the work, the discrepancies were quantified using the parameters of mean and standard deviation (SD). Pearson's product-moment correlational analysis was used to test correlation of the data, which is quantified using a parameter of r. The trajectory profiles acquired by the gating systems show good agreement with those reference profiles. A quantitative analysis shows that the average mean discrepancies between BrainLAB ExacTrac system and known references are 1.5 mm and 1.9 mm for artificial and patient profiles, with the maximum motion amplitude of 28.0 mm. As for the Varian RPM system, the corresponding average mean discrepancies are 1.1 mm and 1.7 mm for artificial and patient profiles. With the proposed single-exposure method, the time delays are found to be 0.20 ± 0.03 seconds and 0.09 ± 0.01 seconds for BrainLAB ExacTrac and Varian RPM systems, respectively. The results indicate the systems can track motion and control radiation delivery with reasonable accuracy. The proposed single-exposure method has been demonstrated to be feasible in measuring time delay efficiently.

Authors
Chang, Z; Liu, T; Cai, J; Chen, Q; Wang, Z; Yin, F-F
MLA Citation
Chang, Z, Liu, T, Cai, J, Chen, Q, Wang, Z, and Yin, F-F. "Evaluation of integrated respiratory gating systems on a Novalis Tx system. (Published online)" J Appl Clin Med Phys 12.3 (April 4, 2011): 3495-.
PMID
21844863
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
12
Issue
3
Publish Date
2011
Start Page
3495

Crescent artifacts in cone-beam CT.

PURPOSE: In image-guided radiation therapy, cone-beam CT has been adopted for three-dimensional target localization in the treatment room. In many of these cone-beam CT images, dark and light crescent artifacts can be seen. This study investigates potential causes of this artifact and a technique for mitigating the crescents. METHODS: Three deviations from an ideal geometry were simulated to assess their ability to cause crescent artifacts: Bowtie filter sag, x-ray tube sag, and x-ray tube rotation. The magnitudes of these deviations were estimated by matching shifts in simulated projections to those observed with clinical systems. To correct the artifacts, angle-dependent blank projections were acquired and incorporated into image reconstruction. The degree of artifact reduction was evaluated with varying numbers (1-380) of blank projections. Scanner-acquired phantom and patient studies were conducted to demonstrate the effectiveness of the proposed correction method. RESULTS: All three investigated causes of the crescent artifact introduced similar mismodeling of the acquired projections and similar crescent artifacts. The deviations required for these artifacts were in the range of 0.5-5 mm or 0.1 degrees. RMS error is reduced from 8.91 x 10(-4) to 5.25 x 10(-7) for 1-380 blank projections over a 200 degrees scan angle. In the patient and phantom studies, reconstructions that utilized 380 blank projections largely mitigated the crescent artifacts. CONCLUSIONS: Small deviations from an ideal geometry can result in crescent artifacts due to steep gradients in the bowtie filter. Angle-dependent blank projections can largely alleviate the artifacts.

Authors
Giles, W; Bowsher, J; Li, H; Yin, F-F
MLA Citation
Giles, W, Bowsher, J, Li, H, and Yin, F-F. "Crescent artifacts in cone-beam CT." Med Phys 38.4 (April 2011): 2116-2121.
PMID
21626944
Source
pubmed
Published In
Medical physics
Volume
38
Issue
4
Publish Date
2011
Start Page
2116
End Page
2121
DOI
10.1118/1.3567508

Adaptive prostate IGRT combining online re-optimization and re-positioning: a feasibility study.

In prostate radiation therapy, inter-fractional organ motion/deformation has posed significant challenges on reliable daily dose delivery. To correct for this issue, off-line re-optimization and online re-positioning have been used clinically. In this paper, we propose an adaptive images guided radiation therapy (AIGRT) scheme that combines these two correction methods in an anatomy-driven fashion. The AIGRT process first tries to find a best plan for the daily target from a plan pool, which consists of the original CT plan and all previous re-optimized plans. If successful, the selected plan is used for daily treatment with translational shifts. Otherwise, the AIGRT invokes the re-optimization process of the CT plan for the anatomy of the day, which is afterward added to the plan pool as a candidate for future fractions. The AIGRT scheme is evaluated by comparisons with daily re-optimization and online re-positioning techniques based on daily target coverage, organs at risk (OAR) sparing and implementation efficiency. Simulated treatment courses for 18 patients with re-optimization alone, re-positioning alone and AIGRT shows that AIGRT offers reliable daily target coverage that is highly comparable to daily re-optimization and significantly improves from re-positioning. AIGRT is also seen to provide improved OAR sparing compared to re-positioning. Apart from dosimetric benefits, AIGRT in addition offers an efficient scheme to integrate re-optimization to current re-positioning-based IGRT workflow.

Authors
Li, T; Thongphiew, D; Zhu, X; Lee, WR; Vujaskovic, Z; Yin, F-F; Wu, QJ
MLA Citation
Li, T, Thongphiew, D, Zhu, X, Lee, WR, Vujaskovic, Z, Yin, F-F, and Wu, QJ. "Adaptive prostate IGRT combining online re-optimization and re-positioning: a feasibility study." Phys Med Biol 56.5 (March 7, 2011): 1243-1258.
PMID
21285485
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
56
Issue
5
Publish Date
2011
Start Page
1243
End Page
1258
DOI
10.1088/0031-9155/56/5/002

A planning quality evaluation tool for prostate adaptive IMRT based on machine learning.

PURPOSE: To ensure plan quality for adaptive IMRT of the prostate, we developed a quantitative evaluation tool using a machine learning approach. This tool generates dose volume histograms (DVHs) of organs-at-risk (OARs) based on prior plans as a reference, to be compared with the adaptive plan derived from fluence map deformation. METHODS: Under the same configuration using seven-field 15 MV photon beams, DVHs of OARs (bladder and rectum) were estimated based on anatomical information of the patient and a model learned from a database of high quality prior plans. In this study, the anatomical information was characterized by the organ volumes and distance-to-target histogram (DTH). The database consists of 198 high quality prostate plans and was validated with 14 cases outside the training pool. Principal component analysis (PCA) was applied to DVHs and DTHs to quantify their salient features. Then, support vector regression (SVR) was implemented to establish the correlation between the features of the DVH and the anatomical information. RESULTS: DVH/DTH curves could be characterized sufficiently just using only two or three truncated principal components, thus, patient anatomical information was quantified with reduced numbers of variables. The evaluation of the model using the test data set demonstrated its accuracy approximately 80% in prediction and effectiveness in improving ART planning quality. CONCLUSIONS: An adaptive IMRT plan quality evaluation tool based on machine learning has been developed, which estimates OAR sparing and provides reference in evaluating ART.

Authors
Zhu, X; Ge, Y; Li, T; Thongphiew, D; Yin, F-F; Wu, QJ
MLA Citation
Zhu, X, Ge, Y, Li, T, Thongphiew, D, Yin, F-F, and Wu, QJ. "A planning quality evaluation tool for prostate adaptive IMRT based on machine learning." Med Phys 38.2 (February 2011): 719-726.
PMID
21452709
Source
pubmed
Published In
Medical physics
Volume
38
Issue
2
Publish Date
2011
Start Page
719
End Page
726
DOI
10.1118/1.3539749

Feasibility study of an intensity-modulated radiation model for the study of erectile dysfunction.

INTRODUCTION: Preclinical studies of radiotherapy (RT) induced erectile dysfunction (ED) have been limited by radiation toxicity when using large fields. AIM: To develop a protocol of rat prostate irradiation using techniques mimicking the current clinical standard of intensity modulated radiotherapy (IMRT). MAIN OUTCOME MEASURES: Quality assurance (QA) testing of plan accuracy, animal health 9 weeks after RT, and intracavernosal pressure (ICP) measurement on cavernosal nerve stimulation. METHODS: Computed tomography-based planning was used to develop a stereotactic radiosurgery (SRS) treatment plan for five young adult male Sprague-Dawley rats. Two treatment planning strategies were utilized to deliver 20 Gy in a single fraction: three-dimensional dynamic conformal arc and intensity-modulated arc (RapidArc). QA testing was performed for each plan type. Treatment was delivered using a NovalisTX (Varian Medical Systems) with high-definition multi-leaf collimators using on-board imaging prior to treatment. Each animal was evaluated for ED 2 months after treatment by nerve stimulation and ICP measurement. RESULTS: The mean prostate volume and target volume (5 mm expansion of prostate) for the five animals was 0.36 and 0.66 cm3, respectively. Both conformal and RapidArc plans provided at least 95% coverage of the target volume, with rapid dose fall-off. QA plans demonstrated strong agreement between doses of calculated and delivered plans, although the conformal arc plan was more homogenous in treatment delivery. Treatment was well tolerated by the animals with no toxicity out to 9 weeks. Compared with control animals, significant reduction in ICP/mean arterial pressure, maximum ICP, and ICP area under the curve were noted. CONCLUSION: Tightly conformal dynamic arc prostate irradiation is feasible and results in minimal toxicity and measurable changes in erectile function.

Authors
Koontz, BF; Yan, H; Kimura, M; Vujaskovic, Z; Donatucci, C; Yin, F-F
MLA Citation
Koontz, BF, Yan, H, Kimura, M, Vujaskovic, Z, Donatucci, C, and Yin, F-F. "Feasibility study of an intensity-modulated radiation model for the study of erectile dysfunction." J Sex Med 8.2 (February 2011): 411-418.
PMID
21143413
Source
pubmed
Published In
The Journal of Sexual Medicine
Volume
8
Issue
2
Publish Date
2011
Start Page
411
End Page
418
DOI
10.1111/j.1743-6109.2010.02125.x

Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations.

Dosimetry in kilovoltage cone beam computed tomography (CBCT) is a challenge due to the limitation of physical measurements. To address this, we used a Monte Carlo (MC) method to estimate the CT dose index (CTDI) and the dose length product (DLP) for a commercial CBCT system. As Dixon and Boone showed that CTDI concept can be applicable to both CBCT and conventional CT, we evaluated weighted CT dose index (CTDI(w)) and DLP for a commercial CBCT system. Two extended CT phantoms were created in our BEAMnrc/EGSnrc MC system. Before the simulations, the beam collimation of a Varian On-Board Imager (OBI) system was measured with radiochromic films (model: XR-QA). The MC model of the OBI X-ray tube, validated in a previous study, was used to acquire the phase space files of the full-fan and half-fan cone beams. Then, DOSXYZnrc user code simulated a total of 20 CBCT scans for the nominal beam widths from 1 cm to 10 cm. After the simulations, CBCT dose profiles at center and peripheral locations were extracted and integrated (dose profile integral, DPI) to calculate the CTDI per each beam width. The weighted cone-beam CTDI (CTDI(w,l)) was calculated from DPI values and mean CTDI(w,l) (CTDI(w,l)) and DLP were derived. We also evaluated the differences of CTDI(w) values between MC simulations and point dose measurements using standard CT phantoms. In results, it was found that CTDI(w,600) was 8.74 ± 0.01 cGy for head and CTDI(w,900) was 4.26 ± 0.01 cGy for body scan. The DLP was found to be proportional to the beam collimation. We also found that the point dose measurements with standard CT phantoms can estimate the CTDI within 3% difference compared to the full integrated CTDI from the MC method. This study showed the usability of CTDI as a dose index and DLP as a total dose descriptor in CBCT scans.

Authors
Kim, S; Song, H; Samei, E; Yin, F-F; Yoshizumi, TT
MLA Citation
Kim, S, Song, H, Samei, E, Yin, F-F, and Yoshizumi, TT. "Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations. (Published online)" J Appl Clin Med Phys 12.2 (January 19, 2011): 3395-.
PMID
21587186
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
12
Issue
2
Publish Date
2011
Start Page
3395

Digital tomosynthesis for respiratory gated liver treatment: clinical feasibility for daily image guidance.

PURPOSE: Breath-hold (BH) treatment minimizes internal target volumes (ITV) when treating sites prone to motion. Digital tomosynthesis (DTS) imaging has advantages over cone-beam CT (CBCT) for BH imaging: BH-DTS scan can be completed during a single breath-hold, whereas BH-CBCT is usually acquired by parsing the gantry rotation into multiple BH segments. This study evaluates the localization accuracy of DTS for BH treatment of liver tumors. METHODS: Both planning CT and on-board DTS/CBCT images were acquired under BH, using the planning CT BH window as reference. Onboard imaging data sets included two independent DTS orientations (coronal and sagittal), and CBCT images. Soft tissue target positioning was measured by each imaging modality and translated into couch shifts. Performance of the two DTS orientations was evaluated by comparing target positioning with the CBCT benchmark, determined by two observers. RESULTS: Image data sets were collected from thirty-eight treatment fractions (14 patients). Mean differences between the two DTS methods and the CBCT method were <1 mm in all directions (except the lateral direction with sagittal-DTS: 1.2 mm); the standard deviation was in the range of 2.1-3.5 mm for all techniques. The Pearson correlation showed good interobserver agreement for the coronal-DTS (0.72-0.78). The interobserver agreement for the sagittal-DTS was good for the in-plane directions (0.70-0.82), but poor in the out-of-plane direction (lateral, 0.26). CONCLUSIONS: BH-DTS may be a simpler alternative to BH-CBCT for onboard soft tissue localization of the liver, although the precision of DTS localization appears to be somewhat lower because of the presence of subtle out-of-plane blur.

Authors
Wu, QJ; Meyer, J; Fuller, J; Godfrey, D; Wang, Z; Zhang, J; Yin, F-F
MLA Citation
Wu, QJ, Meyer, J, Fuller, J, Godfrey, D, Wang, Z, Zhang, J, and Yin, F-F. "Digital tomosynthesis for respiratory gated liver treatment: clinical feasibility for daily image guidance." Int J Radiat Oncol Biol Phys 79.1 (January 1, 2011): 289-296.
PMID
20646848
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
79
Issue
1
Publish Date
2011
Start Page
289
End Page
296
DOI
10.1016/j.ijrobp.2010.01.047

Dosimetric comparison of 6 MV and 15 MV single arc rapidarc to helical TomoTherapy for the treatment of pancreatic cancer.

We conducted a planning study to compare Varian's RapidArc (RA) and helical TomoTherapy (HT) for the treatment of pancreatic cancer. Three intensity-modulated radiotherapy (IMRT) plans were generated for 8 patients with pancreatic cancer: one using HT with 6-MV beam (Plan_(HT6)), one using single-arc RA with 6-MV beam (Plan_(RA6)), and one using single-arc RA with 15-MV beam (Plan_(RA15)). Dosimetric indices including high/low conformality index (CI(100%)/CI(50%)), heterogeneity index (HI), monitor units (MUs), and doses to organs at risk (OARs) were compared. The mean CI(100%) was statistically equivalent with respect to the 2 treatment techniques, as well as beam energy (0.99, 1.01, and 1.02 for Plan_(HT6), Plan_(RA6), and Plan_(RA156,) respectively). The CI(50%) and HI were improved in both RA plans over the HT plan. The RA plans significantly reduced MU (MU(RA6) = 697, MU(RA15) = 548) compared with HT (MU(HT6) = 6177, p = 0.008 in both cases). The mean maximum cord dose was decreased from 29.6 Gy in Plan_(HT6) to 21.6 Gy (p = 0.05) in Plan_(RA6) and 21.7 Gy (p = 0.04) in Plan_(RA15). The mean bowel dose decreased from 17.2 Gy in Plan_(HT6) to 15.2 Gy (p = 0.03) in Plan_(RA6) and 15.0 Gy (p = 0.03) Plan_(RA15). The mean liver dose decreased from 8.4 Gy in Plan_(HT6) to 6.3 Gy (p = 0.04) in Plan_(RA6) and 6.2 Gy in Plan_(RA15). Variations of the mean dose to the duodenum, kidneys, and stomach were statistically insignificant. RA and HT can both deliver conformal dose distributions to target volumes while limiting the dose to surrounding OARs in the treatment of pancreatic cancer. Dosimetric advantages might be gained by using RA over HT by reducing the dose to OARs and total MUs used for treatment.

Authors
Cai, J; Yue, J; McLawhorn, R; Yang, W; Wijesooriya, K; Dunlap, NE; Sheng, K; Yin, F-F; Benedict, SH
MLA Citation
Cai, J, Yue, J, McLawhorn, R, Yang, W, Wijesooriya, K, Dunlap, NE, Sheng, K, Yin, F-F, and Benedict, SH. "Dosimetric comparison of 6 MV and 15 MV single arc rapidarc to helical TomoTherapy for the treatment of pancreatic cancer." Med Dosim 36.3 (2011): 317-320.
PMID
20846850
Source
pubmed
Published In
Medical Dosimetry
Volume
36
Issue
3
Publish Date
2011
Start Page
317
End Page
320
DOI
10.1016/j.meddos.2010.07.002

Evaluation of integrated respiratory gating systems on a Novalis Tx system

The purpose of this study was to investigate the accuracy of motion tracking and radiation delivery control of integrated gating systems on a Novalis Tx system. The study was performed on a Novalis Tx system, which is equipped with Varian Real-time Position Management (RPM) system, and BrainLAB ExacTrac gating systems. In this study, the two systems were assessed on accuracy of both motion tracking and radiation delivery control. To evaluate motion tracking, two artificial motion profiles and five patients' respiratory profiles were used. The motion trajectories acquired by the two gating systems were compared against the references. To assess radiation delivery control, time delays were measured using a single-exposure method. More specifically, radiation is delivered with a 4 mm diameter cone within the phase range of 10%-45% for the BrainLAB ExacTrac system, and within the phase range of 0%-25% for the Varian RPM system during expiration, each for three times. Radiochromic films were used to record the radiation exposures and to calculate the time delays. In the work, the discrepancies were quantified using the parameters of mean and standard deviation (SD). Pearson's product-moment correlational analysis was used to test correlation of the data, which is quantified using a parameter of r. The trajectory profiles acquired by the gating systems show good agreement with those reference profiles. A quantitative analysis shows that the average mean discrepancies between BrainLAB ExacTrac system and known references are 1.5 mm and 1.9 mm for artificial and patient profiles, with the maximum motion amplitude of 28.0 mm. As for the Varian RPM system, the corresponding average mean discrepancies are 1.1 mm and 1.7 mm for artificial and patient profiles. With the proposed single-exposure method, the time delays are found to be 0.20 ± 0.03 seconds and 0.09 ± 0.01 seconds for BrainLAB ExacTrac and Varian RPM systems, respectively. The results indicate the systems can track motion and control radiation delivery with reasonable accuracy. The proposed single-exposure method has been demonstrated to be feasible in measuring time delay efficiently.

Authors
Chang, Z; Liu, T; Cai, J; Chen, Q; Wang, Z; Yin, F-F
MLA Citation
Chang, Z, Liu, T, Cai, J, Chen, Q, Wang, Z, and Yin, F-F. "Evaluation of integrated respiratory gating systems on a Novalis Tx system." Journal of Applied Clinical Medical Physics 12.3 (2011): 71-79.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
12
Issue
3
Publish Date
2011
Start Page
71
End Page
79

Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations of a commercial system

Dosimetry in kilovoltage cone beam computed tomography (CBCT) is a challenge due to the limitation of physical measurements. To address this, we used a Monte Carlo (MC) method to estimate the CT dose index (CTDI) and the dose length product (DLP) for a commercial CBCT system. As Dixon and Boone(1) showed that CTDI concept can be applicable to both CBCT and conventional CT, we evaluated weighted CT dose index (CTDIw) and DLP for a commercial CBCT system. Two extended CT phantoms were created in our BEAMnrc/EGSnrc MC system. Before the simulations, the beam collimation of a Varian On-Board Imager (OBI) system was measured with radiochromic films (model: XR-QA). The MC model of the OBI X-ray tube, validated in a previous study, was used to acquire the phase space files of the full-fan and half-fan cone beams. Then, DOSXYZnrc user code simulated a total of 20 CBCT scans for the nominal beam widths from 1 cm to 10 cm. After the simulations, CBCT dose profiles at center and peripheral locations were extracted and integrated (dose profile integral, DPI) to calculate the CTDI per each beam width. The weighted cone-beam CTDI (CTDIw,l) was calculated from DPI values and mean CTDIw,l (CTDIw,l) and DLP were derived. We also evaluated the differences of CTDIw,1 values between MC simulations and point dose measurements using standard CT phantoms. In results, it was found that,CTDI600w was 8.74 ± 0.01 cGy for head and CTDI900w was 4.26 ± 0.01 cGy for body scan. The DLP was found to be proportional to the beam collimation. We also found that the point dose measurements with standard CT phantoms can estimate the CTDI within 3% difference compared to the full integrated CTDI from the MC method. This study showed the usability of CTDI as a dose index and DLP as a total dose descriptor in CBCT scans.

Authors
Kim, S; Song, H; Samei, E; Yin, F-F; Yoshizumi, TT
MLA Citation
Kim, S, Song, H, Samei, E, Yin, F-F, and Yoshizumi, TT. "Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations of a commercial system." Journal of Applied Clinical Medical Physics 12.2 (2011): 84-95.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
12
Issue
2
Publish Date
2011
Start Page
84
End Page
95

Response to comment on: A planning quality evaluation tool for prostate adaptive IMRT based on machine learning' Med. Phys. 38, 719 (2011)

Authors
Zhu, X; Li, T; Yin, F-F; Wu, QJ; Ge, Y
MLA Citation
Zhu, X, Li, T, Yin, F-F, Wu, QJ, and Ge, Y. "Response to comment on: A planning quality evaluation tool for prostate adaptive IMRT based on machine learning' Med. Phys. 38, 719 (2011)." Medical Physics 38.5 (2011): 2821--.
Source
scival
Published In
Medical physics
Volume
38
Issue
5
Publish Date
2011
Start Page
2821-
DOI
10.1118/1.3578613

Fourier Transform (FT) Techniques for Markerless 4D Cone-beam CT (4D-CBCT) Sorting: Comparison between Phase vs. Magnitude

Authors
Vergalasova, I; Cai, J; Yin, F
MLA Citation
Vergalasova, I, Cai, J, and Yin, F. "Fourier Transform (FT) Techniques for Markerless 4D Cone-beam CT (4D-CBCT) Sorting: Comparison between Phase vs. Magnitude." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S59-S59.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S59
End Page
S59

Correlation between External Surrogate Motion and Lung Tumor Motion: From a Statistical Point of View

Authors
Zhang, F; Kelsey, C; Yin, F; Cai, J
MLA Citation
Zhang, F, Kelsey, C, Yin, F, and Cai, J. "Correlation between External Surrogate Motion and Lung Tumor Motion: From a Statistical Point of View." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S781-S782.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S781
End Page
S782

Dosimetric Evaluation and Optimization of a Novel CBCT Estimation Method for Adaptive Radiation Therapy (ART)

Authors
Ren, L; Jin, J; Movsas, B; Yin, F; Chetty, I
MLA Citation
Ren, L, Jin, J, Movsas, B, Yin, F, and Chetty, I. "Dosimetric Evaluation and Optimization of a Novel CBCT Estimation Method for Adaptive Radiation Therapy (ART)." 2011.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S821
End Page
S821

RTOG 0631 Phase II/III Study of Image-guided Stereotactic Radiosurgery for Localized Spine Metastases: Phase II Results

Authors
Ryu, S; James, J; Gerszten, P; Yin, F; Timmerman, R; Hitchcock, Y; Movsas, B; Kanner, A; Berk, L; Kachnic, L
MLA Citation
Ryu, S, James, J, Gerszten, P, Yin, F, Timmerman, R, Hitchcock, Y, Movsas, B, Kanner, A, Berk, L, and Kachnic, L. "RTOG 0631 Phase II/III Study of Image-guided Stereotactic Radiosurgery for Localized Spine Metastases: Phase II Results." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S131-S132.
PMID
24890347
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S131
End Page
S132

A Dual-Isocenter Technique for Image Guidance of Prone-Breast Radiation Therapy

Authors
Yoo, S; O'Daniel, J; Horton, J; Blitzblau, R; Yin, F
MLA Citation
Yoo, S, O'Daniel, J, Horton, J, Blitzblau, R, and Yin, F. "A Dual-Isocenter Technique for Image Guidance of Prone-Breast Radiation Therapy." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S824-S825.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S824
End Page
S825

Apparatus-dependent dosimetric differences in spine stereotactic body radiotherapy.

The purpose of this investigation was to study apparatus-dependent dose distribution differences specific to spine stereotactic body radiotherapy (SBRT) treatment planning. This multi-institutional study was performed evaluating an image-guided robotic radiosurgery system (CK), intensity modulated protons (IMP), multileaf collimator (MLC) fixed-field IMRT with 5 mm (11 field), 4 mm (9 field), and 2.5 mm (8- and 9-field) leaf widths and intensity modulated volumetric arc therapy (IMVAT) with a 2.5 mm MLC. Treatment plans were systematically developed for targets consisting of one, two and three consecutive thoracic vertebral bodies (VBs) with the esophagus and spinal cord contoured as the organs at risk. It was found that all modalities achieved acceptable treatment planning constraints. However, following normalization fixed field IMRT with a 2.5 mm MLC, IMVAT and IMP systems yielded the smallest ratio of maximum dose divided by the prescription dose (MD/PD) for one-, two- and three-VB PTVs (ranging from 1.1-1.16). The 2.5 mm MLC 9-field IMRT, IMVAT and CK plans resulted in the least dose to 0.1 cc volumes of spinal cord and esophagus. CK plans had the greatest degree of target dose inhomogeneity. As the level of complexity increased with an increasing number of vertebral bodies, distinct apparatus features such as the use of a high number of beams and a finer leaf size MLC were favored. Our study quantified apparatus-dependent dose-distribution differences specific to spine SBRT given strict, but realistic, constraints and highlights the need to benchmark physical dose distributions for multi-institutional clinical trials.

Authors
Ma, L; Sahgal, A; Cozzi, L; Chang, E; Shiu, A; Letourneau, D; Yin, F-F; Fogliata, A; Kaissl, W; Hyde, D; Laperriere, NJ; Shrieve, DC; Larson, DA
MLA Citation
Ma, L, Sahgal, A, Cozzi, L, Chang, E, Shiu, A, Letourneau, D, Yin, F-F, Fogliata, A, Kaissl, W, Hyde, D, Laperriere, NJ, Shrieve, DC, and Larson, DA. "Apparatus-dependent dosimetric differences in spine stereotactic body radiotherapy." Technol Cancer Res Treat 9.6 (December 2010): 563-574.
PMID
21070078
Source
pubmed
Published In
Technology in cancer research & treatment
Volume
9
Issue
6
Publish Date
2010
Start Page
563
End Page
574
DOI
10.1177/153303461000900604

Maximum intensity projection (MIP) imaging using slice-stacking MRIa).

To evaluate the feasibility of acquiring maximum intensity projection (MIP) images using a novel slice-stacking MRI (SS-MRI) technique.The proposed technique employed a steady state acquisition sequence to image multiple axial slices. At each axial slice, the scan is repeated throughout one respiratory cycle. Four objects (small, medium, and large triangles, and a cylinder) moving with a patient breathing trajectory were imaged repeatedly for six times using the slice-stacking MRI and 4D-CT.MIPSS-MRI and MIP4D-CT were reconstructed. The internal target volume (ITV) was segmented for each object on the six scans and compared between MIPSS-MRI and MIP4D-CT. The medium triangle was also imaged with various motion patterns using slice-stacking MRI, 4D-CT, and sagittal cine-MRI. The corresponding MIP images were reconstructed and volume/area measurements were performed and compared between different imaging methods. Three healthy volunteers underwent the slice-stacking MRI and sagittal cine-MRI scans. A region of interest (ROI) was selected and contoured for each subject in both MIPSS-MRI and MIPcine-MRI. The area of the selected ROI was computed and compared.Volume comparison betweenMIPSS-MRI and MIP4D-CT showed statistically insignificant (p>0.05 in all cases) difference in the mean ITVs for all four objects. For the study of the medium triangle with multiple motion patterns, there was a good agreement in the measured ITVs between MIPSS-MRI and MIP4D-CT (p=0.46, correlation coefficient=0.91), with a mean difference of 1.4%±4.4%. The area measurements between MIPSS-MRI and MIPcine-MRI also showed good agreement (p=0.47, correlation coefficient=0.97), with a mean difference of 0.2%±2.9%. For the healthy volunteer study, the average difference in the area of selected ROI was -2.5%±2.5% between MIPSS-MRI and MIPcine-MRI.These preliminary results showed good agreement in volume/area measurements between the slice-stacking MRI technique and 4D-CT/cine-MRI, indicating that it is feasible to use this technique for MIP imaging.

Authors
Adamson, J; Chang, Z; Wang, Z; Yin, F-F; Cai, J
MLA Citation
Adamson, J, Chang, Z, Wang, Z, Yin, F-F, and Cai, J. "Maximum intensity projection (MIP) imaging using slice-stacking MRIa)." Medical physics 37.11 (November 2010): 5914-5920.
PMID
28525010
Source
epmc
Published In
Medical physics
Volume
37
Issue
11
Publish Date
2010
Start Page
5914
End Page
5920
DOI
10.1118/1.3503850

Maximum intensity projection (MIP) imaging using slice-stacking MRI.

PURPOSE: To evaluate the feasibility of acquiring maximum intensity projection (MIP) images using a novel slice-stacking MRI (SS-MRI) technique. METHODS: The proposed technique employed a steady state acquisition sequence to image multiple axial slices. At each axial slice, the scan is repeated throughout one respiratory cycle. Four objects (small, medium, and large triangles, and a cylinder) moving with a patient breathing trajectory were imaged repeatedly for six times using the slice-stacking MRI and 4D-CT. MIP(SS-MRI) and MIP(4D-CT) were reconstructed. The internal target volume (ITV) was segmented for each object on the six scans and compared between MIP(SS-MRI) and MIP(4D-CT). The medium triangle was also imaged with various motion patterns using slice-stacking MRI, 4D-CT, and sagittal cine-MRI. The corresponding MIP images were reconstructed and volume/area measurements were performed and compared between different imaging methods. Three healthy volunteers underwent the slice-stacking MRI and sagittal cine-MRI scans. A region of interest (ROI) was selected and contoured for each subject in both MIP(SS-MRI) and MIP(cine-MRI). The area of the selected ROI was computed and compared. RESULTS: Volume comparison between MIP(SS-MRI) and MIP(4D-CT) showed statistically insignificant (p > 0.05 in all cases) difference in the mean ITVs for all four objects. For the study of the medium triangle with multiple motion patterns, there was a good agreement in the measured ITVs between MIP(SS-MRI) and MIP(4D-CT) (p = 0.46, correlation coefficient = 0.91), with a mean difference of 1.4% +/- 4.4%. The area measurements between MIP(SS-MRI) and MIP(cine-MRI) also showed good agreement (p=0.47, correlation coefficient = 0.97), with a mean difference of 0.2% +/- 2.9%. For the healthy volunteer study, the average difference in the area of selected ROI was -2.5% +/- 2.5% between MIP(SS-MRI) and MIP(cine-MRI). CONCLUSIONS: These preliminary results showed good agreement in volume/area measurements between the slice-stacking MRI technique and 4D-CT/cine-MRI, indicating that it is feasible to use this technique for MIP imaging.

Authors
Adamson, J; Chang, Z; Wang, Z; Yin, F-F; Cai, J
MLA Citation
Adamson, J, Chang, Z, Wang, Z, Yin, F-F, and Cai, J. "Maximum intensity projection (MIP) imaging using slice-stacking MRI." Med Phys 37.11 (November 2010): 5914-5920.
PMID
21158304
Source
pubmed
Published In
Medical physics
Volume
37
Issue
11
Publish Date
2010
Start Page
5914
End Page
5920
DOI
10.1118/1.3503850

Impact of volumetric modulated arc therapy technique on treatment with partial breast irradiation.

PURPOSE: To investigate the technical feasibility of volumetric modulated arc therapy (V-MAT) in the delivery of partial breast irradiation (PBI). METHODS AND MATERIALS: V-MAT and the standard, three-dimensional conformal radiotherapy (3D-CRT), were compared retrospectively in 8 patients previously treated with PBI. These patients' plans were replanned with a single partial arc using V-MAT that included partial blocking to minimize normal tissue dose. Dosimetric parameters were calculated to evaluate plan quality. Quality assurance studies included verifying both the point and the multiple planar doses. Total monitor units and delivery time were also evaluated, and collision clearance was analyzed. RESULTS: Volumes of ipsilateral lung irradiated to 10 Gy (V10) and 20 Gy (V20) by V-MAT were significantly less than those of 3D-CRT (p = 0.03 for V10 and p = 0.025 for V20). The volume of ipsilateral breast irradiated to 5 Gy was significantly less by using V-MAT than with 3D-CRT (p = 0.02), with a ratio of integrated dose of <1.00. The total mean monitor units (489 +/- 38) for V-MAT were significantly less than those for 3D-CRT (634 +/- 123) (p = 0.017), with a 23% reduction. The average machine delivery time was 1.21 +/- 0.10 min for the V-MAT plans and 6.28 +/- 1.40 min for the 3D-CRT plans, resulting in a reduction factor of 80.1%. The conformity indexes were 1.3 in the V-MAT plans and 1.5 in the 3D-CRT plans (p = 0.102). CONCLUSIONS: V-MAT technology is feasible for PBI patients. Compared to a conventional 3D-CRT technique, it is more efficient, offers equivalent or better dose conformity, delivers lower doses to the ipsilateral lung and breast, and may potentially reduce intrafractional motion.

Authors
Qiu, J-J; Chang, Z; Wu, QJ; Yoo, S; Horton, J; Yin, F-F
MLA Citation
Qiu, J-J, Chang, Z, Wu, QJ, Yoo, S, Horton, J, and Yin, F-F. "Impact of volumetric modulated arc therapy technique on treatment with partial breast irradiation." Int J Radiat Oncol Biol Phys 78.1 (September 1, 2010): 288-296.
PMID
20444558
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
78
Issue
1
Publish Date
2010
Start Page
288
End Page
296
DOI
10.1016/j.ijrobp.2009.10.036

Direction-dependent localization errors in SPECT images.

PURPOSE: Single photon emission computed tomography (SPECT) is being investigated for imaging inside radiation therapy treatment rooms to localize biological targets. Here, computer simulations were used to analyze locational and directional dependencies in localization errors and to assess the effects of spatial resolution modeling and observer normalization on localization performance. METHODS: SPECT images of the XCAT phantom, containing 12 hot tumors, were reconstructed with detector response function compensation (DRC) and without DRC (nDRC). Numerical observers were forced to select the most suspicious tumor location, using normalized cross correlation (NXC) or un-normalized cross correlation (XC), from 3 cm diameter search volumes that each contained only one tumor. For each tumor site, localization was optimized as a function of the iteration number and postreconstruction smoothing. Localization error, the distance between true and estimated tumor positions, was calculated across the ensembles of 80 images. Direction-dependent localization bias and precision were estimated from the image ensemble. RESULTS: For the six superficial tumors in close proximity to the detector trajectory, mean localization errors were < 2 mm and were lowest or comparable using DRC-NXC, though differences from DRC-XC and nDRC-NXC were not statistically significant. DRC-NXC did provide statistically significantly better localization than nDRC-XC for five of these six tumors. At the other six sites where attenuation was more severe and the distance was generally greater between the tumor and detector, DRC typically did not show better localization than nDRC. Observer normalization improved the localization substantially for a tumor near the hotter heart. Localization errors were anisotropic and dependent on tumor location relative to the detector trajectory. CONCLUSIONS: This computer-simulation study compared localization performance for normalized and un-normalized numerical observers, which were used to estimate tumor positions in SPECT images, reconstructed with and without DRC. For tumors localized to < 2 mm on average, which are good candidates for SPECT-guided radiation therapy, localization performance typically improved by compensating for the detector response function and by using a normalized observer. The observed direction-dependent localization errors have important implications for radiation therapy and are relevant to SPECT imaging in general.

Authors
Roper, J; Bowsher, J; Yin, F-F
MLA Citation
Roper, J, Bowsher, J, and Yin, F-F. "Direction-dependent localization errors in SPECT images." Med Phys 37.9 (September 2010): 4886-4896.
PMID
20964207
Source
pubmed
Published In
Medical physics
Volume
37
Issue
9
Publish Date
2010
Start Page
4886
End Page
4896
DOI
10.1118/1.3481515

Effects of breathing variation on gating window internal target volume in respiratory gated radiation therapya).

To investigate the effects of breathing variation on gating window internal target volume(ITVGW) in respiratory gated radiation therapy.Two-dimensional dynamic MRI (dMRI) of lung motion was acquired in ten volunteers and eight lung cancer patients. Resorted dMRI using 4DCT acquisition method (RedCAM) was generated for selected subjects by simulating the image rebinning process. A dynamic software generated phantom (dSGP) was created by moving a solid circle (to mimic the "tumor") with dMRI-determined motion trajectories. The gating window internal target area (ITAGW, 2D counterpart of ITVGW) was determined from both RedCAM and dSGP/dMRI. Its area (A), major axis (L1), minor axis (L2), and similarity (S) were calculated and compared.In the phantom study of 3 cm tumor, measurements of theITAGW from dSGP (A=10.0±1.3cm2, L1=3.8±0.4cm, and L2=3.3±0.1cm) are significantly (p<0.001) greater than those from RedCAM (A=8.5±0.7cm2, L1=3.5±0.2cm, and L2=3.1±0.1cm). Similarly, the differences are significantly greater (p<0.001) for the 1 cm tumor (A=1.9±0.5cm2, L1=1.9±0.4cm, and L2=1.3±0.1cm in dSGP; A=1.3±0.1cm2, L1=1.5±0.2cm, and L2=1.1±0.1cm in RedCAM). In patient studies, measurements of the ITAGW from dMRI (A=15.5±8.2cm2, L1=5.0±1.1cm, and L2=3.8±1.2cm) are also significantly greater (p<0.05) than those from RedCAM (A=13.2±8.5cm2, L1=4.3±1.4cm, and L2=3.7±1.2cm). Similarities were 0.9±0.1, 0.8±0.1, and 0.8±0.1 in the 3 cm tumor phantom, 1 cm tumor phantom, and patient studies, respectively.ITVGW can be underestimated by 4DCT due to breathing variations. An additional margin may be needed to account for this potential error in generating a PTVGW. Cautions need to be taken when generating ITVGW from 4DCT in respiratory gated radiation therapy, especially for small tumors (<3cm) with a large motion range (>1cm).

Authors
Cai, J; McLawhorn, R; Read, PW; Larner, JM; Yin, F-F; Benedict, SH; Sheng, K
MLA Citation
Cai, J, McLawhorn, R, Read, PW, Larner, JM, Yin, F-F, Benedict, SH, and Sheng, K. "Effects of breathing variation on gating window internal target volume in respiratory gated radiation therapya)." Medical physics 37.8 (August 2010): 3927-3934.
PMID
28524317
Source
epmc
Published In
Medical physics
Volume
37
Issue
8
Publish Date
2010
Start Page
3927
End Page
3934
DOI
10.1118/1.3457329

Stereotactic body radiation therapy: the report of AAPM Task Group 101.

Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body radiation therapy (SBRT). The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information is provided for establishing a SBRT program, including protocols, equipment, resources, and QA procedures. Additionally, suggestions for developing consistent documentation for prescribing, reporting, and recording SBRT treatment delivery is provided.

Authors
Benedict, SH; Yenice, KM; Followill, D; Galvin, JM; Hinson, W; Kavanagh, B; Keall, P; Lovelock, M; Meeks, S; Papiez, L; Purdie, T; Sadagopan, R; Schell, MC; Salter, B; Schlesinger, DJ; Shiu, AS; Solberg, T; Song, DY; Stieber, V; Timmerman, R; Tomé, WA; Verellen, D; Wang, L; Yin, F-F
MLA Citation
Benedict, SH, Yenice, KM, Followill, D, Galvin, JM, Hinson, W, Kavanagh, B, Keall, P, Lovelock, M, Meeks, S, Papiez, L, Purdie, T, Sadagopan, R, Schell, MC, Salter, B, Schlesinger, DJ, Shiu, AS, Solberg, T, Song, DY, Stieber, V, Timmerman, R, Tomé, WA, Verellen, D, Wang, L, and Yin, F-F. "Stereotactic body radiation therapy: the report of AAPM Task Group 101." Med Phys 37.8 (August 2010): 4078-4101.
PMID
20879569
Source
pubmed
Published In
Medical physics
Volume
37
Issue
8
Publish Date
2010
Start Page
4078
End Page
4101
DOI
10.1118/1.3438081

Effects of breathing variation on gating window internal target volume in respiratory gated radiation therapy.

PURPOSE: To investigate the effects of breathing variation on gating window internal target volume (ITVGW) in respiratory gated radiation therapy. METHOD AND MATERIALS: Two-dimensional dynamic MRI (dMRI) of lung motion was acquired in ten volunteers and eight lung cancer patients. Resorted dMRI using 4DCT acquisition method (RedCAM) was generated for selected subjects by simulating the image rebinning process. A dynamic software generated phantom (dSGP) was created by moving a solid circle (to mimic the "tumor") with dMRI-determined motion trajectories. The gating window internal target area (ITAGw, 2D counterpart of ITVGW) was determined from both RedCAM and dSGP/dMRI. Its area (A), major axis (L1), minor axis (L2), and similarity (S) were calculated and compared. RESULTS: In the phantom study of 3 cm tumor, measurements of the ITAGW from dSGP (A =10.0 +/- 1.3 cm2, L1=3.8 +/- 0.4 cm, and L2=3.3 +/- 0.1 cm) are significantly (p <0.001) greater than those from RedCAM (A=8.5 +/- 0.7 cm(2), L1 =3.5 +/- 0.2 cm, and L2=3.1 +/- 0.1 cm). Similarly, the differences are significantly greater (p <0.001) for the 1 cm tumor (A=1.9 +/- 0.5 cm(2), L1 =1.9 +/- 0.4 cm, and L2=1.3 +/- 0.1 cm in dSGP; A=l1.3 +/- 0.1 cm(2), L1=1.5 +/- 0.2 cm, and L2 = 1.1 +/- 0.1 cm in RedCAM). In patient studies, measurements of the ITAGW from dMRI (A =15.5 +/- 8.2 cm(2), Ll=5.0 +/- 1.1 cm, and L2=3.8 +/- 1.2 cm) are also significantly greater (p <0.05) than those from RedCAM (A=13.2 +/- 8.5 cm(2), L1=4.3 +/- 1.4 cm, and L2=3.7 +/- 1.2 cm). Similarities were 0.9 +/- 0.1, 0.8 +/- 0.1, and 0.8 +/- 0.1 in the 3 cm tumor phantom, 1 cm tumor phantom, and patient studies, respectively. CONCLUSION: ITVGW can be underestimated by 4DCT due to breathing variations. An additional margin may be needed to account for this potential error in generating a PTVGW. Cautions need to be taken when generating ITVGW from 4DCT in respiratory gated radiation therapy, especially for small tumors (<3 cm) with a large motion range (>1 cm).

Authors
Cai, J; McLawhorn, R; Read, PW; Larner, JM; Yin, F-F; Benedict, SH; Sheng, K
MLA Citation
Cai, J, McLawhorn, R, Read, PW, Larner, JM, Yin, F-F, Benedict, SH, and Sheng, K. "Effects of breathing variation on gating window internal target volume in respiratory gated radiation therapy." Med Phys 37.8 (August 2010): 3927-3934.
PMID
20879555
Source
pubmed
Published In
Medical physics
Volume
37
Issue
8
Publish Date
2010
Start Page
3927
End Page
3934
DOI
10.1118/1.3457329

Arc-modulated radiation therapy based on linear models.

This paper reports an inverse arc-modulated radiation therapy planning technique based on linear models. It is implemented with a two-step procedure. First, fluence maps for 36 fixed-gantry beams are generated using a linear model-based intensity-modulated radiation therapy (IMRT) optimization algorithm. The 2D fluence maps are decomposed into 1D fluence profiles according to each leaf pair position. Second, a mixed integer linear model is used to construct the leaf motions of an arc delivery that reproduce the 1D fluence profile previously derived from the static gantry IMRT optimization. The multi-leaf collimator (MLC) sequence takes into account the starting and ending leaf positions in between the neighbouring apertures, such that the MLC segments of the entire treatment plan are deliverable in a continuous arc. Since both steps in the algorithm use linear models, implementation is simple and straightforward. Details of the algorithm are presented, and its conceptual correctness is verified with clinical cases representing prostate and head-and-neck treatments.

Authors
Zhu, X; Thongphiew, D; McMahon, R; Li, T; Chankong, V; Yin, F-F; Wu, QJ
MLA Citation
Zhu, X, Thongphiew, D, McMahon, R, Li, T, Chankong, V, Yin, F-F, and Wu, QJ. "Arc-modulated radiation therapy based on linear models." Phys Med Biol 55.13 (July 7, 2010): 3873-3883.
PMID
20571210
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
55
Issue
13
Publish Date
2010
Start Page
3873
End Page
3883
DOI
10.1088/0031-9155/55/13/020

Kilovoltage cone-beam CT: comparative dose and image quality evaluations in partial and full-angle scan protocols.

PURPOSE: To assess imaging dose of partial and full-angle kilovoltage CBCT scan protocols and to evaluate image quality for each protocol. METHODS: The authors obtained the CT dose index (CTDI) of the kilovoltage CBCT protocols in an on-board imager by ion chamber (IC) measurements and Monte Carlo (MC) simulations. A total of six new CBCT scan protocols were evaluated: Standard-dose head (100 kVp, 151 mA s, partial-angle), low-dose head (100 kVp, 75 mA s, partial-angle), high-quality head (100 kVp, 754 mA s, partial-angle), pelvis (125 kVp, 706 mA s, full-angle), pelvis spotlight (125 kVp, 752 mA s, partial-angle), and low-dose thorax (110 kVp, 271 mA s, full-angle). Using the point dose method, various CTDI values were calculated by (1) the conventional weighted CTDI (CTDIw) calculation and (2) Bakalyar's method (CTDIwb). The MC simulations were performed to obtain the CTDIw and CTDIwb, as well as from (3) central slice averaging (CTDI(2D)) and (4) volume averaging (CTDI(3D)) techniques. The CTDI values of the new protocols were compared to those of the old protocols (full-angle CBCT protocols). Image quality of the new protocols was evaluated following the CBCT image quality assurance (QA) protocol [S. Yoo et al., "A quality assurance program for the on-board image, "Med. Phys. 33(11), 4431-4447 (2006)] testing Hounsfield unit (HU) linearity, spatial linearity/resolution, contrast resolution, and HU uniformity. RESULTS: The CTDI, were found as 6.0, 3.2, 29.0, 25.4, 23.8, and 7.7 mGy for the new protocols, respectively. The CTDI, and CTDIwb differed within +3% between IC measurements and MC simulations. Method (2) results were within +/- 12% of method (1). In MC simulations, the CTDIw and CTDIwb were comparable to the CTDI(2D) and CTDI(3D) with the differences ranging from -4.3% to 20.6%. The CTDI(3D) were smallest among all the CTDI values. CTDIw of the new protocols were found as approximately 14 times lower for standard head scan and 1.8 times lower for standard body scan than the old protocols, respectively. In the image quality QA tests, all the protocols except low-dose head and low-dose thorax protocols were within the tolerance in the HU verification test. The HU value for the two protocols was always higher than the nominal value. All the protocols passed the spatial linearity/resolution and HU uniformity tests. In the contrast resolution test, only high-quality head and pelvis scan protocols were within the tolerance. In addition, crescent effect was found in the partial-angle scan protocols. CONCLUSIONS: The authors found that CTDIw of the new CBCT protocols has been significantly reduced compared to the old protocols with acceptable image quality. The CTDIw values in the point dose method were close to the volume averaging method within 9%-21% for all the CBCT scan protocols. The Bakalyar's method produced more accurate dose estimation within 14%. The HU inaccuracy from low-dose head and low-dose thorax protocols can render incorrect dose results in the treatment planning system. When high soft-tissue contrast data are desired, high-quality head or pelvis scan protocol is recommended depending on the imaging area. The point dose method can be applicable to estimate CBCT dose with reasonable accuracy in the clinical environment.

Authors
Kim, S; Yoo, S; Yin, F-F; Samei, E; Yoshizumi, T
MLA Citation
Kim, S, Yoo, S, Yin, F-F, Samei, E, and Yoshizumi, T. "Kilovoltage cone-beam CT: comparative dose and image quality evaluations in partial and full-angle scan protocols." Med Phys 37.7 (July 2010): 3648-3659.
PMID
20831072
Source
pubmed
Published In
Medical physics
Volume
37
Issue
7
Publish Date
2010
Start Page
3648
End Page
3659
DOI
10.1118/1.3438478

Increased nucleolar localization of SpiA3G in classically but not alternatively activated macrophages.

Macrophages play a key role in innate immune response to pathogens and in tissue homeostasis, inflammation and repair. A serpin A3G (SpiA3G) is highly induced in classically activated macrophages. We show increased localization of SpiA3G in the nucleolus and co-localization with cathepsin L, upon classical, but not alternative activation of macrophages. Despite the increased expression of cathepsin L in the nuclei of classically activated macrophages, no cathepsin activity was detected. Since only pro-inflammatory, but not anti-inflammatory stimuli induce increased nucleolar localization of SpiA3G, we propose that SpiA3g translocation into the nucleolus is important in host defense against pathogens.

Authors
Konjar, S; Yin, F; Bogyo, M; Turk, B; Kopitar-Jerala, N
MLA Citation
Konjar, S, Yin, F, Bogyo, M, Turk, B, and Kopitar-Jerala, N. "Increased nucleolar localization of SpiA3G in classically but not alternatively activated macrophages." FEBS letters 584.11 (June 2010): 2201-2206.
PMID
20338168
Source
epmc
Published In
FEBS Letters
Volume
584
Issue
11
Publish Date
2010
Start Page
2201
End Page
2206
DOI
10.1016/j.febslet.2010.03.031

TU-C-204B-06: Performance Evaluation of a Dual Cone-Beam CT (Dual CBCT) System

Authors
Li, H; Giles, W; Roper, J; Bowsher, J; Yin, F
MLA Citation
Li, H, Giles, W, Roper, J, Bowsher, J, and Yin, F. "TU-C-204B-06: Performance Evaluation of a Dual Cone-Beam CT (Dual CBCT) System." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part13
Publish Date
2010
Start Page
3385
End Page
3385
DOI
10.1118/1.3469229

SU-GG-T-136: Treatment Plans Comparison with Static-Gantry IMRT and RapidArcTM for Head-And-Neck Cancers Involving Cervical Lymph Nodes

Authors
Yoo, S; Das, S; Wu, Q; Brizel, D; Yin, F
MLA Citation
Yoo, S, Das, S, Wu, Q, Brizel, D, and Yin, F. "SU-GG-T-136: Treatment Plans Comparison with Static-Gantry IMRT and RapidArcTM for Head-And-Neck Cancers Involving Cervical Lymph Nodes." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part17
Publish Date
2010
Start Page
3216
End Page
3216
DOI
10.1118/1.3468526

TU-B-201B-02: Self-Sorted Four-Dimensional CT Using Body Volume as Respiratory Surrogate

Authors
Cai, J; Chang, Z; Yin, F
MLA Citation
Cai, J, Chang, Z, and Yin, F. "TU-B-201B-02: Self-Sorted Four-Dimensional CT Using Body Volume as Respiratory Surrogate." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part6
Publish Date
2010
Start Page
3378
End Page
3378
DOI
10.1118/1.3469198

SU-GG-I-148: Self-Sorted Four-Dimensional Magnetic Resonance Imaging: A Feasibility Study

Authors
Cai, J; Chang, Z; Yin, F
MLA Citation
Cai, J, Chang, Z, and Yin, F. "SU-GG-I-148: Self-Sorted Four-Dimensional Magnetic Resonance Imaging: A Feasibility Study." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part5
Publish Date
2010
Start Page
3135
End Page
3135
DOI
10.1118/1.3468183

SU-GG-I-24: Improving IGRT Efficiency Using GPU-Based Ultrafast Reconstruction of DTS/CBCT and DRR

Authors
Jian, Y; Godfrey, D; Chang, Z; Yin, F
MLA Citation
Jian, Y, Godfrey, D, Chang, Z, and Yin, F. "SU-GG-I-24: Improving IGRT Efficiency Using GPU-Based Ultrafast Reconstruction of DTS/CBCT and DRR." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part3
Publish Date
2010
Start Page
3106
End Page
3106
DOI
10.1118/1.3468057

SU-GG-J-62: Use Winston-Lutz Test to Check Cone Beam CT Isocenter Accuracy for Imaging Guided Intracranial Stereotactic Radiosurgery

Authors
Wang, Z; Chang, Z; Chen, Q; Yin, F
MLA Citation
Wang, Z, Chang, Z, Chen, Q, and Yin, F. "SU-GG-J-62: Use Winston-Lutz Test to Check Cone Beam CT Isocenter Accuracy for Imaging Guided Intracranial Stereotactic Radiosurgery." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part10
Publish Date
2010
Start Page
3159
End Page
3159
DOI
10.1118/1.3468286

SU-GG-I-144: Accelerating Non-Contrast-Enhanced MRA with Inflow Inversion Recovery by Using Skipped Phase Encoding and Edge Deghosting (SPEED)

Authors
Chang, Z; Xiang, Q; Shen, H; Yin, F
MLA Citation
Chang, Z, Xiang, Q, Shen, H, and Yin, F. "SU-GG-I-144: Accelerating Non-Contrast-Enhanced MRA with Inflow Inversion Recovery by Using Skipped Phase Encoding and Edge Deghosting (SPEED)." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part5
Publish Date
2010
Start Page
3134
End Page
3134
DOI
10.1118/1.3468179

SU-GG-T-225: Gantry-Angle Dependence of a 2D Ion Chamber Array for IMAT QA

Authors
O'Daniel, J; Kishore, M; Das, S; Wu, QJ; Yoo, S; Yin, F
MLA Citation
O'Daniel, J, Kishore, M, Das, S, Wu, QJ, Yoo, S, and Yin, F. "SU-GG-T-225: Gantry-Angle Dependence of a 2D Ion Chamber Array for IMAT QA." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part19
Publish Date
2010
Start Page
3237
End Page
3237
DOI
10.1118/1.3468616

SU-GG-T-137: Similarities between Static and Rotational Intensity Modulated Plans

Authors
Wu, Q; Yin, F; McMahon, R; Zhu, X; Das, S
MLA Citation
Wu, Q, Yin, F, McMahon, R, Zhu, X, and Das, S. "SU-GG-T-137: Similarities between Static and Rotational Intensity Modulated Plans." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part17
Publish Date
2010
Start Page
3216
End Page
3216
DOI
10.1118/1.3468527

SU-GG-T-583: Dosimetric Comparison of Anisotropic Analytical and Pencil Beam Convolution Algorithms in Breast Cancer Radiation Treatment Planning

Authors
Yoo, S; O'Daniel, J; Horton, J; Wu, Q; Yin, F
MLA Citation
Yoo, S, O'Daniel, J, Horton, J, Wu, Q, and Yin, F. "SU-GG-T-583: Dosimetric Comparison of Anisotropic Analytical and Pencil Beam Convolution Algorithms in Breast Cancer Radiation Treatment Planning." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part25
Publish Date
2010
Start Page
3321
End Page
3321
DOI
10.1118/1.3468984

TH-C-204B-07: Development of Image-Guided Radiosurgery with Novalis TX for Small Animal Study

Authors
Yan, H; Koontz, B; Kimura, M; Vujaskovic, Z; Yin, F
MLA Citation
Yan, H, Koontz, B, Kimura, M, Vujaskovic, Z, and Yin, F. "TH-C-204B-07: Development of Image-Guided Radiosurgery with Novalis TX for Small Animal Study." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part13
Publish Date
2010
Start Page
3456
End Page
3456
DOI
10.1118/1.3469500

SU-GG-T-362: Is Distance-Dependent Energy Correction Needed for Dosimetric Measurements Surrounding Brachytherapy Sources?

Authors
Song, H; Oldham, M; Yin, F
MLA Citation
Song, H, Oldham, M, and Yin, F. "SU-GG-T-362: Is Distance-Dependent Energy Correction Needed for Dosimetric Measurements Surrounding Brachytherapy Sources?." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part21
Publish Date
2010
Start Page
3269
End Page
3269
DOI
10.1118/1.3468759

SU-GG-I-57: Dose and Image Quality Evaluation for Partial and Full-Angle Kilovoltage Cone-Beam CT Protocols

Authors
Kim, S; Yoo, S; Yin, F; Samei, E; Yoshizumi, T
MLA Citation
Kim, S, Yoo, S, Yin, F, Samei, E, and Yoshizumi, T. "SU-GG-I-57: Dose and Image Quality Evaluation for Partial and Full-Angle Kilovoltage Cone-Beam CT Protocols." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part3
Publish Date
2010
Start Page
3114
End Page
3114
DOI
10.1118/1.3468090

SU-EE-A1-03: Arc Modulated Radiation Therapy Based on Linear Models

Authors
Zhu, X; Thongphiew, D; McMahon, R; Li, T; Chankong, V; Yin, F; Wu, Q
MLA Citation
Zhu, X, Thongphiew, D, McMahon, R, Li, T, Chankong, V, Yin, F, and Wu, Q. "SU-EE-A1-03: Arc Modulated Radiation Therapy Based on Linear Models." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part25
Publish Date
2010
Start Page
3094
End Page
3095
DOI
10.1118/1.3468008

SU-GG-J-76: Validation of a Proposed Optimal Slow Gantry Rotation Technique for On-Board Four-Dimensional Imaging Using Lung Patient Data

Authors
Maurer, J; Vergalasova, I; Pan, T; Yin, F
MLA Citation
Maurer, J, Vergalasova, I, Pan, T, and Yin, F. "SU-GG-J-76: Validation of a Proposed Optimal Slow Gantry Rotation Technique for On-Board Four-Dimensional Imaging Using Lung Patient Data." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part10
Publish Date
2010
Start Page
3162
End Page
3162
DOI
10.1118/1.3468300

TH-A-BRA-03: TG-104: In-Room kV Imaging for IGRT

Authors
Yin, F; Wong, J; Jaffray, D
MLA Citation
Yin, F, Wong, J, and Jaffray, D. "TH-A-BRA-03: TG-104: In-Room kV Imaging for IGRT." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part14
Publish Date
2010
Start Page
3446
End Page
3446
DOI
10.1118/1.3469462

SU-DD-A3-03: How Accurately Can the Internal Target Volume (ITV) from a Free-Breathing Cone Beam Computed Tomography (FB-CBCT) Scan Be Used for Target Verification?

Authors
Vergalasova, I; Maurer, J; Yin, F
MLA Citation
Vergalasova, I, Maurer, J, and Yin, F. "SU-DD-A3-03: How Accurately Can the Internal Target Volume (ITV) from a Free-Breathing Cone Beam Computed Tomography (FB-CBCT) Scan Be Used for Target Verification?." June 2010.
Source
crossref
Published In
Medical physics
Volume
37
Issue
6Part12
Publish Date
2010
Start Page
3091
End Page
3091
DOI
10.1118/1.3467996

Estimation of computed tomography dose index in cone beam computed tomography: MOSFET measurements and Monte Carlo simulations.

To address the lack of accurate dose estimation method in cone beam computed tomography (CBCT), we performed point dose metal oxide semiconductor field-effect transistor (MOSFET) measurements and Monte Carlo (MC) simulations. A Varian On-Board Imager (OBI) was employed to measure point doses in the polymethyl methacrylate (PMMA) CT phantoms with MOSFETs for standard and low dose modes. A MC model of the OBI x-ray tube was developed using BEAMnrc/EGSnrc MC system and validated by the half value layer, x-ray spectrum and lateral and depth dose profiles. We compared the weighted computed tomography dose index (CTDIw) between MOSFET measurements and MC simulations. The CTDIw was found to be 8.39 cGy for the head scan and 4.58 cGy for the body scan from the MOSFET measurements in standard dose mode, and 1.89 cGy for the head and 1.11 cGy for the body in low dose mode, respectively. The CTDIw from MC compared well to the MOSFET measurements within 5% differences. In conclusion, a MC model for Varian CBCT has been established and this approach may be easily extended from the CBCT geometry to multi-detector CT geometry.

Authors
Kim, S; Yoshizumi, T; Toncheva, G; Yoo, S; Yin, F-F; Frush, D
MLA Citation
Kim, S, Yoshizumi, T, Toncheva, G, Yoo, S, Yin, F-F, and Frush, D. "Estimation of computed tomography dose index in cone beam computed tomography: MOSFET measurements and Monte Carlo simulations." Health Phys 98.5 (May 2010): 683-691.
PMID
20386198
Source
pubmed
Published In
Health Physics
Volume
98
Issue
5
Publish Date
2010
Start Page
683
End Page
691
DOI
10.1097/HP.0b013e3181cd3ec3

6D image guidance for spinal non-invasive stereotactic body radiation therapy: Comparison between ExacTrac X-ray 6D with kilo-voltage cone-beam CT.

PURPOSE: To investigate setup discrepancies measured with ExacTrac X-ray 6 degree-of-freedom (6D) and cone-beam computed tomography (CBCT) for patients under treatments of stereotactic body radiation therapy (SBRT). MATERIALS AND METHODS: In this work, phantom and patient studies were performed. In the phantom studies, an anthropomorphic phantom was placed with pre-defined positions, and imaged with ExacTrac X-ray 6D and CBCT to test the accuracy of the imaging systems. In the patient studies, 16 spinal SBRT patient cases were retrospectively analyzed. The patients were initially positioned in customized immobilization cradles and then aligned with ExacTrac X-ray 6D and CBCT. The setup discrepancies were computed and quantitatively analyzed. RESULTS: This study indicates modest discrepancies between ExacTrac X-ray 6D and CBCT with spinal SBRT. The phantom experiments showed that translational and rotational discrepancies in root-mean-square (RMS) between ExacTrac X-ray 6D and CBCT were, respectively, <1.0mm and <1 degrees . In the retrospective patient studies, translational and rotational discrepancies in RMS between ExacTrac X-ray 6D and CBCT were <2.0mm and <1.5 degrees . CONCLUSIONS: ExacTrac X-ray 6D represents a potential alternative to CBCT; however, pre-caution should be taken when only ExacTrac X-ray 6D is used to guide SBRT with small setup margins.

Authors
Chang, Z; Wang, Z; Ma, J; O'Daniel, JC; Kirkpatrick, J; Yin, F-F
MLA Citation
Chang, Z, Wang, Z, Ma, J, O'Daniel, JC, Kirkpatrick, J, and Yin, F-F. "6D image guidance for spinal non-invasive stereotactic body radiation therapy: Comparison between ExacTrac X-ray 6D with kilo-voltage cone-beam CT." Radiother Oncol 95.1 (April 2010): 116-121.
PMID
20122747
Source
pubmed
Published In
Radiotherapy and Oncology
Volume
95
Issue
1
Publish Date
2010
Start Page
116
End Page
121
DOI
10.1016/j.radonc.2009.12.036

Radiotherapy treatment plans with RapidArc for prostate cancer involving seminal vesicles and lymph nodes.

PURPOSE: Dosimetric results and treatment delivery efficiency of RapidArc plans to those of conventional intensity-modulated radiotherapy (IMRT) plans were compared using the Eclipse treatment planning system for high-risk prostate cancer. MATERIALS AND METHODS: This study included 10 patients. The primary planning target volume (PTV(P)) contained prostate, seminal vesicles, and pelvic lymph nodes with a margin. The boost PTV (PTV(B)) contained prostate and seminal vesicles with a margin. The total prescription dose was 75.6 Gy (46.8 Gy to PTV(P) and an additional 28.8 Gy to PTV(B); 1.8 Gy/fraction). Three plans were generated for each PTV: Multiple-field IMRT, one-arc RapidArc (1ARC), and two-arc RapidArc (2ARC). RESULTS: In the primary IMRT with PTV(P), average mean doses to bladder, rectum and small bowel were lower by 5.9%, 7.7% and 4.3%, respectively, than in the primary 1ARC and by 3.6%, 4.8% and 3.1%, respectively, than in the primary 2ARC. In the boost IMRT with PTV(B), average mean doses to bladder and rectum were lower by 2.6% and 4.8% than with the boost 1ARC and were higher by 0.6% and 0.2% than with the boost 2ARC. Integral doses were 7% to 9% higher with RapidArc than with IMRT for both primary and boost plans. Treatment delivery time was reduced by 2-7 minutes using RapidArc. CONCLUSION: For PTVs including prostate, seminal vesicles, and lymph nodes, IMRT performed better in dose sparing for bladder, rectum, and small bowel than did RapidArc. For PTVs including prostate and seminal vesicles, RapidArc with two arcs provided plans comparable to those for IMRT. The treatment delivery is more efficient with RapidArc.

Authors
Yoo, S; Wu, QJ; Lee, WR; Yin, F-F
MLA Citation
Yoo, S, Wu, QJ, Lee, WR, and Yin, F-F. "Radiotherapy treatment plans with RapidArc for prostate cancer involving seminal vesicles and lymph nodes." Int J Radiat Oncol Biol Phys 76.3 (March 1, 2010): 935-942.
PMID
20044214
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
76
Issue
3
Publish Date
2010
Start Page
935
End Page
942
DOI
10.1016/j.ijrobp.2009.07.1677

Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry.

Authors
Kim, S; Yoshizumi, TT; Toncheva, G; Frush, DP; Yin, F-F
MLA Citation
Kim, S, Yoshizumi, TT, Toncheva, G, Frush, DP, and Yin, F-F. "Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations." Radiat Prot Dosimetry 138.3 (March 2010): 257-263.
PMID
19889800
Source
pubmed
Published In
Radiation Protection Dosimetry
Volume
138
Issue
3
Publish Date
2010
Start Page
257
End Page
263
DOI
10.1093/rpd/ncp257

Accelerating non-contrast-enhanced MR angiography with inflow inversion recovery imaging by skipped phase encoding and edge deghosting (SPEED).

PURPOSE: To accelerate non-contrast-enhanced MR angiography (MRA) with inflow inversion recovery (IFIR) with a fast imaging method, Skipped Phase Encoding and Edge Deghosting (SPEED). MATERIALS AND METHODS: IFIR imaging uses a preparatory inversion pulse to reduce signals from static tissue, while leaving inflow arterial blood unaffected, resulting in sparse arterial vasculature on modest tissue background. By taking advantage of vascular sparsity, SPEED can be simplified with a single-layer model to achieve higher efficiency in both scan time reduction and image reconstruction. SPEED can also make use of information available in multiple coils for further acceleration. The techniques are demonstrated with a three-dimensional renal non-contrast-enhanced IFIR MRA study. RESULTS: Images are reconstructed by SPEED based on a single-layer model to achieve an undersampling factor of up to 2.5 using one skipped phase encoding direction. By making use of information available in multiple coils, SPEED can achieve an undersampling factor of up to 8.3 with four receiver coils. The reconstructed images generally have comparable quality as that of the reference images reconstructed from full k-space data. CONCLUSION: As demonstrated with a three-dimensional renal IFIR scan, SPEED based on a single-layer model is able to reduce scan time further and achieve higher computational efficiency than the original SPEED.

Authors
Chang, Z; Xiang, Q-S; Shen, H; Yin, F-F
MLA Citation
Chang, Z, Xiang, Q-S, Shen, H, and Yin, F-F. "Accelerating non-contrast-enhanced MR angiography with inflow inversion recovery imaging by skipped phase encoding and edge deghosting (SPEED)." J Magn Reson Imaging 31.3 (March 2010): 757-765.
PMID
20187224
Source
pubmed
Published In
Journal of Magnetic Resonance Imaging
Volume
31
Issue
3
Publish Date
2010
Start Page
757
End Page
765
DOI
10.1002/jmri.22069

Point/counterpoint. The traditional L-shaped gantry for radiotherapy linear accelerators will soon become obsolete.

Authors
Stancanello, J; Yin, F-F; Orton, CG
MLA Citation
Stancanello, J, Yin, F-F, and Orton, CG. "Point/counterpoint. The traditional L-shaped gantry for radiotherapy linear accelerators will soon become obsolete." Med Phys 37.2 (February 2010): 409-411.
PMID
20229848
Source
pubmed
Published In
Medical physics
Volume
37
Issue
2
Publish Date
2010
Start Page
409
End Page
411
DOI
10.1118/1.3276730

Slow gantry rotation acquisition technique for on-board four-dimensional digital tomosynthesis.

PURPOSE: Four-dimensional cone-beam computed tomography (4D CBCT) has been investigated for motion imaging in the radiotherapy treatment room. The drawbacks of 4D CBCT are long scan times and high imaging doses. The aims of this study were to develop and investigate a slow gantry rotation acquisition protocol for four-dimensional digital tomosynthesis (4D DTS) as a faster, lower dose alternative to 4D CBCT. METHODS: This technique was implemented using an On-Board Imager kV imaging system (Varian Medical Systems, Palo Alto, CA) mounted on the gantry of a linear accelerator. The general procedure for 4D DTS imaging using slow gantry rotation acquisition consists of the following steps: (1) acquire projections over a limited gantry rotation angle in a single motion with constant frame rate and gantry rotation speed; (2) generate a respiratory signal and temporally match projection images with appropriate points from the respiratory signal; (3) use the respiratory signal to assign phases to each of the projection images; (4) sort projection images into phase bins; and (5) reconstruct phase images. Phantom studies were conducted to validate theoretically derived relationships between acquisition and respiratory parameters. Optimization of acquisition parameters was then conducted by simulating lung scans using patient data. Lung tumors with approximate volumes ranging from 0.12 to 1.53 cm3 were studied. RESULTS: A protocol for slow gantry rotation 4D DTS was presented. Equations were derived to express relationships between acquisition parameters (frame rate, phase window, and angular intervals between projections), respiratory cycle durations, and resulting acquisition times and numbers of projections. The phantom studies validated the relationships, and the patient studies resulted in determinations of appropriate acquisition parameters. The phase window must be set according to clinical goals. For 10% phase windows, we found that appropriate frame rates ranging from 2 to 5 frames/s, gantry rotation speeds ranging from 0.44 to 1.03 degrees/s, and aiming for an approximate maximum angular interval of 3.4 degrees between projections in phase bins were appropriate for dose, scan time, and tumor visibility optimization. Adequate tumor visibility was achieved for coronal 4D DTS images of all three lung tumors with acquisition times ranging from 0.45 to 2.12 min. vs. 1.84 to 4.24 min for 4D CBCT. 4D DTS imaging doses ranged from 0.12 to 0.72 times the dose of a standard CBCT scan vs 0.48 to 1.44 times the dose of a standard CBCT scan for 4D CBCT. CONCLUSIONS: A slow gantry rotation acquisition technique for 4D DTS was developed and investigated. Study results indicated that 4D DTS is a feasible technique for imaging lung tumor motion in the treatment room and requires shorter acquisition times and less imaging dose than 4D CBCT for larger tumors that do not require large scan angles for sagittal views and for situations where only coronal views are needed to meet clinical needs.

Authors
Maurer, J; Pan, T; Yin, F-F
MLA Citation
Maurer, J, Pan, T, and Yin, F-F. "Slow gantry rotation acquisition technique for on-board four-dimensional digital tomosynthesis." Med Phys 37.2 (February 2010): 921-933.
PMID
20229901
Source
pubmed
Published In
Medical physics
Volume
37
Issue
2
Publish Date
2010
Start Page
921
End Page
933
DOI
10.1118/1.3285291

A methodology for selecting the beam arrangement to reduce the intensity-modulated radiation therapy (IMRT) dose to the SPECT-defined functioning lung.

Macroaggregated albumin single-photon emission computed tomography (MAA-SPECT) provides a map of the spatial distribution of lung perfusion. Our previous work developed a methodology to use SPECT guidance to reduce the dose to the functional lung in IMRT planning. This study aims to investigate the role of beam arrangement on both low and high doses in the functional lung. In our previous work, nine-beam IMRT plans were generated with and without SPECT guidance and compared for five patients. For the current study, the dose-function histogram (DFH) contribution for each of the nine beams for each patient was calculated. Four beams were chosen based on orientation and DFH contributions to create a SPECT-guided plan that spared the functional lung and maintained target coverage. Four-beam SPECT-guided IMRT plans reduced the F(20) and F(30) values by (16.5 +/- 6.8)% and (6.1 +/- 9.2)%, respectively, when compared to nine-beam conventional IMRT plans. Moreover, the SPECT-4F Plan reduces F(5) and F(13) for all patients by (11.0 +/- 8.2)% and (6.1 +/- 3.6)%, respectively, compared to the SPECT Plan. Using fewer beams in IMRT planning may reduce the amount of functional lung that receives 5 and 13 Gy, a factor that has recently been associated with radiation pneumonitis.

Authors
McGuire, SM; Marks, LB; Yin, FF; Das, SK
MLA Citation
McGuire, SM, Marks, LB, Yin, FF, and Das, SK. "A methodology for selecting the beam arrangement to reduce the intensity-modulated radiation therapy (IMRT) dose to the SPECT-defined functioning lung." Phys Med Biol 55.2 (January 21, 2010): 403-416.
PMID
20019404
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
55
Issue
2
Publish Date
2010
Start Page
403
End Page
416
DOI
10.1088/0031-9155/55/2/005

Similarities between static and rotational intensity-modulated plans.

The aim of this study was to explore similarities between intensity-modulated radiotherapy (IMRT) and intensity-modulated arc therapy (IMAT) techniques in the context of the number of multi-leaf collimator (MLC) segments required to achieve plan objectives, the major factor influencing plan quality. Three clinical cases with increasing complexity were studied: (a) prostate only, (b) prostate and seminal vesicles and (c) prostate and pelvic lymph nodes. Initial 'gold-standard' plans with the maximum possible organ-at-risk sparing were generated for all three cases. For each case, multiple IMRT and IMAT plans were generated with varying intensity levels (IMRT) and arc control points (IMAT), which translate into varying MLC segments in both modalities. The IMAT/IMRT plans were forced to mimic the organ-at-risk sparing and target coverage in the gold-standard plans, thereby only allowing the target dose inhomogeneity to be variable. A higher target dose inhomogeneity (quantified as D5--dose to the highest 5% of target volume) implies that the plan is less capable of modulation. For each case, given a similar number of MLC segments, both IMRT and IMAT plans exhibit similar target dose inhomogeneity, indicating that there is no difference in their ability to provide dose painting. Target dose inhomogeneity remained approximately constant with decreasing segments, but sharply increased below a specific critical number of segments (70, 100, 110 for cases a, b, c, respectively). For the cases studied, IMAT and IMRT plans are similar in their dependence on the number of MLC segments. A minimum critical number of segments are required to ensure adequate plan quality. Future studies are needed to establish the range of minimum critical number of segments for different treatment sites and target-organ geometries.

Authors
Wu, QJ; Yin, F-F; McMahon, R; Zhu, X; Das, SK
MLA Citation
Wu, QJ, Yin, F-F, McMahon, R, Zhu, X, and Das, SK. "Similarities between static and rotational intensity-modulated plans." Phys Med Biol 55.1 (January 7, 2010): 33-43.
PMID
19949257
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
55
Issue
1
Publish Date
2010
Start Page
33
End Page
43
DOI
10.1088/0031-9155/55/1/003

Radiation dose from cone beam CT in a pediatric phantom: risk estimation of cancer incidence.

OBJECTIVE: The objective of our study was to measure absorbed doses and calculate effective dose (ED) from cone beam CT (CBCT) with metal oxide semiconductor field effect transistor (MOSFET) detectors in an anthropomorphic phantom and to estimate the risk of cancer incidence for CBCT. MATERIALS AND METHODS: Abdominal CBCT was performed in an anthropomorphic phantom of a 5-year-old child using the On-Board Imager with arbitrarily designated standard-dose (125 kVp, 80 mA, 25 milliseconds) and low-dose (125 kVp, 40 mA, 10 milliseconds) modes. The full-fan mode was used, and 20 MOSFET dosimeters were used to measure the absorbed doses in various organs. We calculated the ED, the lifetime attributable risk (LAR) for cancer incidence, and relative risk (RR) of cancer induction from a single scan for both standard- and low-dose modes in 5-year-old children. RESULTS: The highest absorbed doses were found in the skin, ascending colon, and stomach. The mean ED was 37.8+/-0.7 (SD) mSv for the standard-dose mode and 8.1+/-0.2 mSv for the low-dose mode. The LAR of cancer incidence ranged from 23 to 144 cases per 100,000 exposed persons for the standard-dose mode and from five to 31 cases per 100,000 exposed persons for the low-dose mode. The RR of cancer incidence ranged from 1.003 to 1.054 for the standard-dose mode and from 1.001 to 1.012 for the low-dose mode. CONCLUSION: The ED from pediatric CBCT using the standard-dose mode was considerably higher than that of MDCT, whereas the ED for CBCT using the low-dose mode was comparable to that of abdominal MDCT. For abdominal CBCT in the pediatric phantom, the highest LARs were for colon and bladder cancers and the highest RRs were for stomach and liver cancers.

Authors
Kim, S; Yoshizumi, TT; Frush, DP; Toncheva, G; Yin, F-F
MLA Citation
Kim, S, Yoshizumi, TT, Frush, DP, Toncheva, G, and Yin, F-F. "Radiation dose from cone beam CT in a pediatric phantom: risk estimation of cancer incidence." AJR Am J Roentgenol 194.1 (January 2010): 186-190.
PMID
20028922
Source
pubmed
Published In
AJR. American journal of roentgenology
Volume
194
Issue
1
Publish Date
2010
Start Page
186
End Page
190
DOI
10.2214/AJR.08.2168

Phase Window and Frame Rate Optimization for On-hoard 4D Imaging Dose Reduction

Authors
Maurer, JM; Yin, F
MLA Citation
Maurer, JM, and Yin, F. "Phase Window and Frame Rate Optimization for On-hoard 4D Imaging Dose Reduction." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S677
End Page
S678

Reduced Cross Scatter in Dual-source Cone-Beam CT by Asynchronous Projection Acquisition

Authors
Giles, WM; Bowsher, J; Yin, F
MLA Citation
Giles, WM, Bowsher, J, and Yin, F. "Reduced Cross Scatter in Dual-source Cone-Beam CT by Asynchronous Projection Acquisition." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S681
End Page
S681

Potentially Underestimating the Internal Target Volume (ITV) in Free-Breathing Cone-Beam CT (CBCT)

Authors
Vergalasova, I; Maurer, J; Yin, F
MLA Citation
Vergalasova, I, Maurer, J, and Yin, F. "Potentially Underestimating the Internal Target Volume (ITV) in Free-Breathing Cone-Beam CT (CBCT)." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S672
End Page
S672

Dosimetry challenges for implementing emerging technologies.

During the last 10 years, radiation therapy technologies have gone through major changes, mainly related introduction of sophisticated delivery and imaging techniques to improve the target localization accuracy and dose conformity. While implementation of these emerging technologies such as image-guided SRS/SBRT, IMRT/IMAT, IGRT, 4D motion management, and special delivery technologies showed substantial clinical gains for patient care, many other factors, such as training/quality, efficiency/efficacy, and cost/effectiveness etc. remain to be challenging. This talk will address technical challenges for dosimetry verification of implementing these emerging technologies in radiation therapy.

Authors
Yin, F-F; Oldham, M; Cai, J; Wu, Q
MLA Citation
Yin, F-F, Oldham, M, Cai, J, and Wu, Q. "Dosimetry challenges for implementing emerging technologies." J Phys Conf Ser 250.1 (2010): 8-11.
PMID
21617745
Source
pubmed
Published In
Journal of Physics
Volume
250
Issue
1
Publish Date
2010
Start Page
8
End Page
11
DOI
10.1088/1742-6596/250/1/012002

On-line adaptive radiation therapy: feasibility and clinical study.

The purpose of this paper is to evaluate the feasibility and clinical dosimetric benefit of an on-line, that is, with the patient in the treatment position, Adaptive Radiation Therapy (ART) system for prostate cancer treatment based on daily cone-beam CT imaging and fast volumetric reoptimization of treatment plans. A fast intensity-modulated radiotherapy (IMRT) plan reoptimization algorithm is implemented and evaluated with clinical cases. The quality of these adapted plans is compared to the corresponding new plans generated by an experienced planner using a commercial treatment planning system and also evaluated by an in-house developed tool estimating achievable dose-volume histograms (DVHs) based on a database of existing treatment plans. In addition, a clinical implementation scheme for ART is designed and evaluated using clinical cases for its dosimetric qualities and efficiency.

Authors
Li, T; Zhu, X; Thongphiew, D; Lee, WR; Vujaskovic, Z; Wu, Q; Yin, F-F; Wu, QJ
MLA Citation
Li, T, Zhu, X, Thongphiew, D, Lee, WR, Vujaskovic, Z, Wu, Q, Yin, F-F, and Wu, QJ. "On-line adaptive radiation therapy: feasibility and clinical study." J Oncol 2010 (2010): 407236-.
PMID
21113304
Source
pubmed
Published In
Journal of Oncology
Volume
2010
Publish Date
2010
Start Page
407236
DOI
10.1155/2010/407236

Regional SPECT imaging using sampling principles and multiple pinholes

There may be many SPECT imaging applications in which a small region is primarily of interest. One such case is imaging in the radiation therapy treatment room, as the patient is on the treatment table in position for radiation therapy. This onboard imaging is currently performed by cone-beam CT. The purpose of this onboard imaging is to fine tune localization of the tumor target. It has been proposed that onboard SPECT could be useful for target localization and also for imaging biological function for the purpose of real-time re-planning of therapy beams. Onboard imaging would need to be accomplished within about 5 minutes. Herein we propose that this might be done by regional SPECT imaging in which multi-pinhole collimation is used to concentrate a large detector surface on a small (e.g. 7cm-diameter) region. Pinhole trajectories are designed in accord with recent developments regarding complete sampling in the presence of truncation. A 9-pinhole system is found to outperform two single-pinhole systems as well as a smaller, reference parallel-hole-collimated detector. Realistic computer-aided design (CAD) studies are shown to illustrate how an onboard SPECT system could be implemented. © 2010 IEEE.

Authors
Bowsher, JE; Roper, JR; Yan, S; Giles, WM; Yin, F-F
MLA Citation
Bowsher, JE, Roper, JR, Yan, S, Giles, WM, and Yin, F-F. "Regional SPECT imaging using sampling principles and multiple pinholes." IEEE Nuclear Science Symposium Conference Record (2010): 2071-2076.
Source
scival
Published In
IEEE Nuclear Science Symposium Conference Record
Publish Date
2010
Start Page
2071
End Page
2076
DOI
10.1109/NSSMIC.2010.5874141

Patient specific quality assurance: Transition from IMRT to IMAT

The purpose of this study was to test a patient-specific quality assurance (QA) protocol for intensity-modulated arc radiotherapy (IMAT), and to evaluate the use of an intensity-modulated stationary radiotherapy QA device (2D ion chamber array). Thirty-nine IMAT treatment plans for brain, spine, and prostate were analyzed using 3 methods: ion chamber (1D absolute, n=39), film (2D relative, coronal/sagittal, n=8), and 2D ion chamber array ("ICA," 2D absolute, coronal/sagittal, n=39) measurements. All measurements were compared to the treatment planning system (TPS) dose calculation with gamma analysis (3%, 3mm distance-to-agreement criteria) or absolute point dose comparison. The ICA measurements were also directly compared to film and ion chamber for validation. Absolute 1D measurements agreed well calculation (ion chamber: average deviation 1.4%, range -0.9% to 2.8%; ICA: average deviation 0.7%, range -1.8% to 2.9%). Relative 2D measurements also showed good agreement with calculation (>93% of pixels in all films passing gamma, >90% of pixels in all ICA measurements passing gamma). ICA and film relative dose results were highly similar (> 90% of pixels passing gamma in 94% of QAs). Coronal and sagittal ICA measurements were statistically indistinguishable by the paired t-test with a hypothesized mean difference of 0.2%. Ion chamber and ICA absolute dose measurements usually agreed well, but had disparities of 2-3% in 18% of plans. After validating the new IMAT implementation with ion chamber, film, and ICA, we reduced our QA from 5 (ion chamber, film, and ICA) to 2 measurements (ion chamber and single ICA) per plan. The ICA (Matrixx®, IBA Dosimetry) was validated in relative analysis mode, but ion chamber measurements are recommended for absolute dose comparison. © 2010 IOP Publishing Ltd.

Authors
O'Daniel, J; Das, S; Wu, J; Yin, F-F
MLA Citation
O'Daniel, J, Das, S, Wu, J, and Yin, F-F. "Patient specific quality assurance: Transition from IMRT to IMAT." Journal of Physics: Conference Series 250 (2010): 231-234.
Source
scival
Published In
Journal of Physics
Volume
250
Publish Date
2010
Start Page
231
End Page
234
DOI
10.1088/1742-6596/250/1/012050

The traditional L-shaped gantry for radiotherapy linear accelerators will soon become obsolete

Authors
Stancanello, J; Yin, F-F; Orton, CG
MLA Citation
Stancanello, J, Yin, F-F, and Orton, CG. "The traditional L-shaped gantry for radiotherapy linear accelerators will soon become obsolete." Medical Physics 37.2 (2010): 409-411.
Source
scival
Published In
Medical physics
Volume
37
Issue
2
Publish Date
2010
Start Page
409
End Page
411
DOI
10.1118/1.3276730

On-board SPECT for Target Localization: A Comprehensive Analysis of Findings from Computer Simulation and Scanner Studies

Authors
Roper, JR; Bowsher, JE; Yin, F
MLA Citation
Roper, JR, Bowsher, JE, and Yin, F. "On-board SPECT for Target Localization: A Comprehensive Analysis of Findings from Computer Simulation and Scanner Studies." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S697
End Page
S698

Extracting Breathing Signal from Image Fourier Transform for Developing 4D-MRI

Authors
Cai, J; Chang, Z; Wang, Z; Yin, F
MLA Citation
Cai, J, Chang, Z, Wang, Z, and Yin, F. "Extracting Breathing Signal from Image Fourier Transform for Developing 4D-MRI." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S727
End Page
S727

Cone-Beam CT 6 Degree-of-Freedom Image-Guidance for Intracranial Frameless Stereotactic RadioSurgery using 6D Robotic Couch

Authors
Chang, Z; Wang, Z; Ma, J; Wu, Q; Kirkpatrick, J; Yin, F
MLA Citation
Chang, Z, Wang, Z, Ma, J, Wu, Q, Kirkpatrick, J, and Yin, F. "Cone-Beam CT 6 Degree-of-Freedom Image-Guidance for Intracranial Frameless Stereotactic RadioSurgery using 6D Robotic Couch." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S280
End Page
S280

Stereotactic Body Radiotherapy (SBRT) in Patients Previously Treated with External Beam Radiation Therapy

Authors
Ghafoori, A; Allen, K; Nelson, J; Clough, R; Yin, F; Wang, Z; Chang, Z; Kelsey, C; Kirkpatrick, J
MLA Citation
Ghafoori, A, Allen, K, Nelson, J, Clough, R, Yin, F, Wang, Z, Chang, Z, Kelsey, C, and Kirkpatrick, J. "Stereotactic Body Radiotherapy (SBRT) in Patients Previously Treated with External Beam Radiation Therapy." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S280
End Page
S281

A Modern Animal Model of Radiation-induced Erectile Dysfunction

Authors
Kimura, M; Koontz, BF; Yan, H; Rabbani, Z; Satoh, T; Baba, S; Yin, F; Donatucci, CF; Polascik, TJ; Vujaskovic, Z
MLA Citation
Kimura, M, Koontz, BF, Yan, H, Rabbani, Z, Satoh, T, Baba, S, Yin, F, Donatucci, CF, Polascik, TJ, and Vujaskovic, Z. "A Modern Animal Model of Radiation-induced Erectile Dysfunction." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S40
End Page
S40

Intensity Modulated Arc Therapy: Effective and Efficient End-to-end Patient Specific Quality Assurance

Authors
O'Daniel, JC; Das, S; Wu, Q; Yin, F
MLA Citation
O'Daniel, JC, Das, S, Wu, Q, and Yin, F. "Intensity Modulated Arc Therapy: Effective and Efficient End-to-end Patient Specific Quality Assurance." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S763
End Page
S763

Breast Cancer Radiation Treatment Planning: A Comparison of Anisotropic Analytical Algorithm (AAA) and Pencil Beam Convolution (PBC) Algorithm

Authors
Yoo, S; Wu, Q; O'Daniel, J; Horton, J; Yin, F
MLA Citation
Yoo, S, Wu, Q, O'Daniel, J, Horton, J, and Yin, F. "Breast Cancer Radiation Treatment Planning: A Comparison of Anisotropic Analytical Algorithm (AAA) and Pencil Beam Convolution (PBC) Algorithm." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S240
End Page
S240

Variation of Clinically Relevant Dose Indices for 3DCRT of Lung with Respect to Dose Calculation Algorithm

Authors
Adamson, JD; Yoo, S; Wu, Q; Yin, F
MLA Citation
Adamson, JD, Yoo, S, Wu, Q, and Yin, F. "Variation of Clinically Relevant Dose Indices for 3DCRT of Lung with Respect to Dose Calculation Algorithm." 2010.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
78
Issue
3
Publish Date
2010
Start Page
S712
End Page
S713

Volumetric arc intensity-modulated therapy for spine body radiotherapy: comparison with static intensity-modulated treatment.

PURPOSE: This clinical study evaluates the feasibility of using volumetric arc-modulated treatment (VMAT) for spine stereotactic body radiotherapy (SBRT) to achieve highly conformal dose distributions that spare adjacent organs at risk (OAR) with reduced treatment time. METHODS AND MATERIALS: Ten spine SBRT patients were studied retrospectively. The intensity-modulated radiotherapy (IMRT) and VMAT plans were generated using either one or two arcs. Planning target volume (PTV) dose coverage, OAR dose sparing, and normal tissue integral dose were measured and compared. Differences in treatment delivery were also analyzed. RESULTS: The PTV DVHs were comparable between VMAT and IMRT plans in the shoulder (D(99%)-D(90%)), slope (D(90%)-D(10%)), and tail (D(10%)-D(1%)) regions. Only VMAT(2arc) had a better conformity index than IMRT (1.09 vs. 1.15, p = 0.007). For cord sparing, IMRT was the best, and VMAT(1arc) was the worst. Use of IMRT achieved greater than 10% more D(1%) sparing for six of 10 cases and 7% to 15% more D(10%) sparing over the VAMT(1arc). The differences between IMRT and VAMT(2arc) were smaller and statistically nonsignificant at all dose levels. The differences were also small and statistically nonsignificant for other OAR sparing. The mean monitor units (MUs) were 8711, 7730, and 6317 for IMRT, VMAT(1arc), and VMAT(2arc) plans, respectively, with a 26% reduction from IMRT to VMAT(2arc). The mean treatment time was 15.86, 8.56, and 7.88 min for IMRT, VMAT(1arc,) and VMAT(2arc). The difference in integral dose was statistically nonsignificant. CONCLUSIONS: Although VMAT provided comparable PTV coverage for spine SBRT, 1arc showed significantly worse spinal cord sparing compared with IMRT, whereas 2arc was comparable to IMRT. Treatment efficiency is substantially improved with the VMAT.

Authors
Wu, QJ; Yoo, S; Kirkpatrick, JP; Thongphiew, D; Yin, F-F
MLA Citation
Wu, QJ, Yoo, S, Kirkpatrick, JP, Thongphiew, D, and Yin, F-F. "Volumetric arc intensity-modulated therapy for spine body radiotherapy: comparison with static intensity-modulated treatment." Int J Radiat Oncol Biol Phys 75.5 (December 1, 2009): 1596-1604.
PMID
19733447
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
75
Issue
5
Publish Date
2009
Start Page
1596
End Page
1604
DOI
10.1016/j.ijrobp.2009.05.005

ExacTrac X-ray 6 degree-of-freedom image-guidance for intracranial non-invasive stereotactic radiotherapy: comparison with kilo-voltage cone-beam CT.

BACKGROUND AND PURPOSE: To compare the residual setup errors measured with ExacTrac X-ray 6 degree-of-freedom (6D) and cone-beam computed tomography (CBCT) for a head phantom and patients receiving intracranial non-invasive fractionated stereotactic radiotherapy (SRT). MATERIALS AND METHODS: Setup data were collected on a Novalis Tx treatment unit for an anthropomorphic head phantom and 18 patients with intracranial tumors. Initial corrections were determined and corrected with the ExacTrac system only, and then the residual setup error was determined by means of three different procedures. These procedures included registrations of ExacTrac X-ray images with the corresponding digitally reconstructed radiographs (DRRs) using the ExacTrac 6D fusion, and registrations of CBCT images with the planning CT using both online 3D fusion and offline 6D fusion. The difference in residual setup errors between ExacTrac system and CBCT was computed. The impact of rotations on the difference was evaluated. RESULTS: A modest difference in residual setup errors was found between ExacTrac system and CBCT. The root-mean-square (RMS) of the differences observed for translations was typically <0.5mm for phantom, and <1.5mm for patients, respectively. The RMS of the differences for rotation(s) was however <0.2 degree for phantom, and <1.0 degree for patients, respectively. The impact of rotation on the setup difference was minor but not negligible. CONCLUSIONS: This study indicates that there is a general agreement between ExacTrac system and CBCT.

Authors
Ma, J; Chang, Z; Wang, Z; Jackie Wu, Q; Kirkpatrick, JP; Yin, F-F
MLA Citation
Ma, J, Chang, Z, Wang, Z, Jackie Wu, Q, Kirkpatrick, JP, and Yin, F-F. "ExacTrac X-ray 6 degree-of-freedom image-guidance for intracranial non-invasive stereotactic radiotherapy: comparison with kilo-voltage cone-beam CT." Radiother Oncol 93.3 (December 2009): 602-608.
PMID
19846229
Source
pubmed
Published In
Radiotherapy and Oncology
Volume
93
Issue
3
Publish Date
2009
Start Page
602
End Page
608
DOI
10.1016/j.radonc.2009.09.009

A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup.

A positioning QA procedure for Varian's 2D/2D (kV/MV) and 3D/3D (planCT/CBCT) matching was developed. The procedure was to check: (1) the coincidence of on-board imager (OBI), portal imager (PI), and cone beam CT (CBCT)'s isocenters (digital graticules) to a linac's isocenter (to a pre-specified accuracy); (2) that the positioning difference detected by 2D/2D (kV/MV) and 3D/3D(planCT/CBCT) matching can be reliably transferred to couch motion. A cube phantom with a 2 mm metal ball (bb) at the center was used. The bb was used to define the isocenter. Two additional bbs were placed on two phantom surfaces in order to define a spatial location of 1.5 cm anterior, 1.5 cm inferior, and 1.5 cm right from the isocenter. An axial scan of the phantom was acquired from a multislice CT simulator. The phantom was set at the linac's isocenter (lasers); either AP MV/R Lat kV images or CBCT images were taken for 2D/2D or 3D/3D matching, respectively. For 2D/2D, the accuracy of each device's isocenter was obtained by checking the distance between the central bb and the digital graticule. Then the central bb in orthogonal DRRs was manually moved to overlay to the off-axis bbs in kV/MV images. For 3D/3D, CBCT was first matched to planCT to check the isocenter difference between the two CTs. Manual shifts were then made by moving CBCT such that the point defined by the two off-axis bbs overlay to the central bb in planCT. (PlanCT can not be moved in the current version of OBI1.4.) The manual shifts were then applied to remotely move the couch. The room laser was used to check the accuracy of the couch movement. For Trilogy (or Ix-21) linacs, the coincidence of imager and linac's isocenter was better than 1 mm (or 1.5 mm). The couch shift accuracy was better than 2 mm.

Authors
Guan, H; Hammoud, R; Yin, F-F
MLA Citation
Guan, H, Hammoud, R, and Yin, F-F. "A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup. (Published online)" J Appl Clin Med Phys 10.4 (October 6, 2009): 2954-.
PMID
19918223
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
10
Issue
4
Publish Date
2009
Start Page
2954

Development of a neuro-fuzzy technique for automated parameter optimization of inverse treatment planning.

BACKGROUND: Parameter optimization in the process of inverse treatment planning for intensity modulated radiation therapy (IMRT) is mainly conducted by human planners in order to create a plan with the desired dose distribution. To automate this tedious process, an artificial intelligence (AI) guided system was developed and examined. METHODS: The AI system can automatically accomplish the optimization process based on prior knowledge operated by several fuzzy inference systems (FIS). Prior knowledge, which was collected from human planners during their routine trial-and-error process of inverse planning, has first to be "translated" to a set of "if-then rules" for driving the FISs. To minimize subjective error which could be costly during this knowledge acquisition process, it is necessary to find a quantitative method to automatically accomplish this task. A well-developed machine learning technique, based on an adaptive neuro fuzzy inference system (ANFIS), was introduced in this study. Based on this approach, prior knowledge of a fuzzy inference system can be quickly collected from observation data (clinically used constraints). The learning capability and the accuracy of such a system were analyzed by generating multiple FIS from data collected from an AI system with known settings and rules. RESULTS: Multiple analyses showed good agreements of FIS and ANFIS according to rules (error of the output values of ANFIS based on the training data from FIS of 7.77 +/- 0.02%) and membership functions (3.9%), thus suggesting that the "behavior" of an FIS can be propagated to another, based on this process. The initial experimental results on a clinical case showed that ANFIS is an effective way to build FIS from practical data, and analysis of ANFIS and FIS with clinical cases showed good planning results provided by ANFIS. OAR volumes encompassed by characteristic percentages of isodoses were reduced by a mean of between 0 and 28%. CONCLUSION: The study demonstrated a feasible way to automatically perform parameter optimization of inverse treatment planning under guidance of prior knowledge without human intervention other than providing a set of constraints that have proven clinically useful in a given setting.

Authors
Stieler, F; Yan, H; Lohr, F; Wenz, F; Yin, F-F
MLA Citation
Stieler, F, Yan, H, Lohr, F, Wenz, F, and Yin, F-F. "Development of a neuro-fuzzy technique for automated parameter optimization of inverse treatment planning. (Published online)" Radiat Oncol 4 (September 25, 2009): 39-.
PMID
19781059
Source
pubmed
Published In
Radiation Oncology
Volume
4
Publish Date
2009
Start Page
39
DOI
10.1186/1748-717X-4-39

Tradeoffs of integrating real-time tracking into IGRT for prostate cancer treatment.

This study investigated the integration of the Calypso real-time tracking system, based on implanted ferromagnetic transponders and a detector array, into the current process for image-guided radiation treatment (IGRT) of prostate cancer at our institution. The current IGRT process includes magnetic resonance imaging (MRI) for prostate delineation, CT simulation for treatment planning, daily on-board kV and CBCT imaging for target alignment, and MRI/MRS for post-treatment assessment. This study assesses (1) magnetic-field-induced displacement and radio-frequency (RF)-induced heating of transponders during MRI at 1.5 T and 3 T, and (2) image artifacts caused by transponders and the detector array in phantom and patient cases with the different imaging systems. A tissue-equivalent phantom mimicking prostate tissue stiffness was constructed and implanted with three operational transponders prior to phantom solidification. The measurements show that the Calypso system is safe with all the imaging systems. Transponder position displacements due to the MR field are minimal (<1.0 mm) for both 1.5 T and 3 T MRI scanners, and the temperature variation due to MRI RF heating is <0.2 degrees C. The visibility of transponders and bony anatomy was not affected on the OBI kV and CT images. Image quality degradation caused by the detector antenna array is observed in the CBCT image. Image artifacts are most significant with the gradient echo sequence in the MR images, producing null signals surrounding the transponders with radii approximately 1.5 cm and length approximately 4 cm. Thus, Calypso transponders can preclude the use of MRI/MRS in post-treatment assessment. Modifications of the clinical flow are required to accommodate and minimize the substantial MRI artifacts induced by the Calypso transponders.

Authors
Zhu, X; Bourland, JD; Yuan, Y; Zhuang, T; O'Daniel, J; Thongphiew, D; Wu, QJ; Das, SK; Yoo, S; Yin, FF
MLA Citation
Zhu, X, Bourland, JD, Yuan, Y, Zhuang, T, O'Daniel, J, Thongphiew, D, Wu, QJ, Das, SK, Yoo, S, and Yin, FF. "Tradeoffs of integrating real-time tracking into IGRT for prostate cancer treatment." Phys Med Biol 54.17 (September 7, 2009): N393-N401.
PMID
19661570
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
54
Issue
17
Publish Date
2009
Start Page
N393
End Page
N401
DOI
10.1088/0031-9155/54/17/N03

Task Group 142 report: quality assurance of medical accelerators.

The task group (TG) for quality assurance of medical accelerators was constituted by the American Association of Physicists in Medicine's Science Council under the direction of the Radiation Therapy Committee and the Quality Assurance and Outcome Improvement Subcommittee. The task group (TG-142) had two main charges. First to update, as needed, recommendations of Table II of the AAPM TG-40 report on quality assurance and second, to add recommendations for asymmetric jaws, multileaf collimation (MLC), and dynamic/virtual wedges. The TG accomplished the update to TG-40, specifying new test and tolerances, and has added recommendations for not only the new ancillary delivery technologies but also for imaging devices that are part of the linear accelerator. The imaging devices include x-ray imaging, photon portal imaging, and cone-beam CT. The TG report was designed to account for the types of treatments delivered with the particular machine. For example, machines that are used for radiosurgery treatments or intensity-modulated radiotherapy (IMRT) require different tests and/or tolerances. There are specific recommendations for MLC quality assurance for machines performing IMRT. The report also gives recommendations as to action levels for the physicists to implement particular actions, whether they are inspection, scheduled action, or immediate and corrective action. The report is geared to be flexible for the physicist to customize the QA program depending on clinical utility. There are specific tables according to daily, monthly, and annual reviews, along with unique tables for wedge systems, MLC, and imaging checks. The report also gives specific recommendations regarding setup of a QA program by the physicist in regards to building a QA team, establishing procedures, training of personnel, documentation, and end-to-end system checks. The tabulated items of this report have been considerably expanded as compared with the original TG-40 report and the recommended tolerances accommodate differences in the intended use of the machine functionality (non-IMRT, IMRT, and stereotactic delivery).

Authors
Klein, EE; Hanley, J; Bayouth, J; Yin, F-F; Simon, W; Dresser, S; Serago, C; Aguirre, F; Ma, L; Arjomandy, B; Liu, C; Sandin, C; Holmes, T; Task Group 142, American Association of Physicists in Medicine,
MLA Citation
Klein, EE, Hanley, J, Bayouth, J, Yin, F-F, Simon, W, Dresser, S, Serago, C, Aguirre, F, Ma, L, Arjomandy, B, Liu, C, Sandin, C, Holmes, T, Task Group 142, and American Association of Physicists in Medicine, . "Task Group 142 report: quality assurance of medical accelerators." Med Phys 36.9 (September 2009): 4197-4212.
PMID
19810494
Source
pubmed
Published In
Medical physics
Volume
36
Issue
9
Publish Date
2009
Start Page
4197
End Page
4212
DOI
10.1118/1.3190392

American Society of Radiation Oncology recommendations for documenting intensity-modulated radiation therapy treatments.

Despite the widespread use of intensity-modulated radiation therapy (IMRT) for approximately a decade, a lack of adequate guidelines for documenting these treatments persists. Proper IMRT treatment documentation is necessary for accurate reconstruction of prior treatments when a patient presents with a marginal recurrence. This is especially crucial when the follow-up care is managed at a second treatment facility not involved in the initial IMRT treatment. To address this issue, an American Society for Radiation Oncology (ASTRO) workgroup within the American ASTRO Radiation Physics Committee was formed at the request of the ASTRO Research Council to develop a set of recommendations for documenting IMRT treatments. This document provides a set of comprehensive recommendations for documenting IMRT treatments, as well as image-guidance procedures, with example forms provided.

Authors
IMRT Documentation Working Group, ; Holmes, T; Das, R; Low, D; Yin, F-F; Balter, J; Palta, J; Eifel, P; FASTRO,
MLA Citation
IMRT Documentation Working Group, , Holmes, T, Das, R, Low, D, Yin, F-F, Balter, J, Palta, J, Eifel, P, and FASTRO, . "American Society of Radiation Oncology recommendations for documenting intensity-modulated radiation therapy treatments." Int J Radiat Oncol Biol Phys 74.5 (August 1, 2009): 1311-1318.
PMID
19616738
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
74
Issue
5
Publish Date
2009
Start Page
1311
End Page
1318
DOI
10.1016/j.ijrobp.2009.04.037

Advances in technology for intracranial stereotactic radiosurgery.

Stereotactic radiosurgery (SRS) refers to a single radiation treatment delivering a high dose to an intra-cranial target localized in three-dimensions by CT and/or MRI imaging. Traditionally, immobilization of the patient's head has been achieved using a rigid stereotactic head frame as the key step in allowing for accurate dose delivery. SRS has been delivered by both Cobalt-60 (Gamma Knife) and linear accelerator (linac) technologies for many decades. The focus of this review is to highlight recent advances and major innovations in SRS technologies relevant to clinical practice and developments allowing for non-invasive frame SRS.

Authors
Sahgal, A; Ma, L; Chang, E; Shiu, A; Larson, DA; Laperriere, N; Yin, F-F; Tsao, M; Menard, C; Basran, PS; Létourneau, D; Heydarian, M; Beachey, D; Shukla, V; Cusimano, M; Hodaie, M; Zadeh, G; Bernstein, M; Schwartz, M
MLA Citation
Sahgal, A, Ma, L, Chang, E, Shiu, A, Larson, DA, Laperriere, N, Yin, F-F, Tsao, M, Menard, C, Basran, PS, Létourneau, D, Heydarian, M, Beachey, D, Shukla, V, Cusimano, M, Hodaie, M, Zadeh, G, Bernstein, M, and Schwartz, M. "Advances in technology for intracranial stereotactic radiosurgery." Technol Cancer Res Treat 8.4 (August 2009): 271-280. (Review)
PMID
19645520
Source
pubmed
Published In
Technology in cancer research & treatment
Volume
8
Issue
4
Publish Date
2009
Start Page
271
End Page
280
DOI
10.1177/153303460900800404

TH-B-BRC-01: Tools for IMRT Commissioning: Static and Rotating Gantries

Authors
Ezzell, G; Yin, F; Xiao, Y
MLA Citation
Ezzell, G, Yin, F, and Xiao, Y. "TH-B-BRC-01: Tools for IMRT Commissioning: Static and Rotating Gantries." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part26
Publish Date
2009
Start Page
2793
End Page
2793
DOI
10.1118/1.3182597

SU-FF-T-309: Quality Assurance for Imaging Guided Stereotactic RadioSurgery with Novalis Tx™ System

Authors
Chang, Z; Wang, Z; Wu, Q; Bowsher, J; Yoo, S; Yin, F
MLA Citation
Chang, Z, Wang, Z, Wu, Q, Bowsher, J, Yoo, S, and Yin, F. "SU-FF-T-309: Quality Assurance for Imaging Guided Stereotactic RadioSurgery with Novalis Tx™ System." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part13
Publish Date
2009
Start Page
2592
End Page
2592
DOI
10.1118/1.3181789

SU-FF-T-130: Radiotherapy Treatment Plans with RapidArc for Head-And-Neck Cancer

Authors
Yoo, S; Das, S; Wu, Q; Brizel, D; Yoo, D; Yin, F
MLA Citation
Yoo, S, Das, S, Wu, Q, Brizel, D, Yoo, D, and Yin, F. "SU-FF-T-130: Radiotherapy Treatment Plans with RapidArc for Head-And-Neck Cancer." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part10
Publish Date
2009
Start Page
2549
End Page
2550
DOI
10.1118/1.3181604

SU-FF-T-545: Feasibility Study for Treatment of Intracranial Multi-Focal Stereotactic Radiosurgery with Multiple Intensity Modulated Arc Technique

Authors
Wang, Z; Kirkpatrick, J; Chang, Z; O'Daniel, J; Willett, C; Yin, F
MLA Citation
Wang, Z, Kirkpatrick, J, Chang, Z, O'Daniel, J, Willett, C, and Yin, F. "SU-FF-T-545: Feasibility Study for Treatment of Intracranial Multi-Focal Stereotactic Radiosurgery with Multiple Intensity Modulated Arc Technique." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part17
Publish Date
2009
Start Page
2649
End Page
2649
DOI
10.1118/1.3182043

SU-FF-T-548: Comparison of Cone-Beam CT and Frame-Based Localizations for Stereotactic Radiosurgery with Fixed Head Rings and Removable Frames

Authors
Wang, Z; Kirkpatrick, J; Wu, Q; Chang, Z; Willett, C; Yin, F
MLA Citation
Wang, Z, Kirkpatrick, J, Wu, Q, Chang, Z, Willett, C, and Yin, F. "SU-FF-T-548: Comparison of Cone-Beam CT and Frame-Based Localizations for Stereotactic Radiosurgery with Fixed Head Rings and Removable Frames." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part17
Publish Date
2009
Start Page
2650
End Page
2650
DOI
10.1118/1.3182046

SU-FF-T-301: Clinical Implementation and Commission of Volumetric Modulated Arc Therapy

Authors
Wu, QJ; McMahon, R; Chang, Z; Zhuang, T; O'Daniel, J; Yoo, S; Zhu, X; Yin, F
MLA Citation
Wu, QJ, McMahon, R, Chang, Z, Zhuang, T, O'Daniel, J, Yoo, S, Zhu, X, and Yin, F. "SU-FF-T-301: Clinical Implementation and Commission of Volumetric Modulated Arc Therapy." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part13
Publish Date
2009
Start Page
2590
End Page
2590
DOI
10.1118/1.3181779

SU-FF-J-56: Integrating Real-Time Tracking Into Image Guided Radiation Therapy for Prostate Cancer Treatment

Authors
Zhu, X; Bourland, J; Yuan, Y; Zhuang, T; O'Daniel, J; Thongphiew, D; Wu, Q; Das, S; Yoo, S; Yin, F
MLA Citation
Zhu, X, Bourland, J, Yuan, Y, Zhuang, T, O'Daniel, J, Thongphiew, D, Wu, Q, Das, S, Yoo, S, and Yin, F. "SU-FF-J-56: Integrating Real-Time Tracking Into Image Guided Radiation Therapy for Prostate Cancer Treatment." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part6
Publish Date
2009
Start Page
2488
End Page
2488
DOI
10.1118/1.3181348

SU-FF-T-158: A Method to Overlay Biological Optimization On Traditional Dose-Volume Constrained Intensity Modulated Radiotherapy (IMRT) Optimization

Authors
Das, S; Yin, F
MLA Citation
Das, S, and Yin, F. "SU-FF-T-158: A Method to Overlay Biological Optimization On Traditional Dose-Volume Constrained Intensity Modulated Radiotherapy (IMRT) Optimization." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part11
Publish Date
2009
Start Page
2556
End Page
2556
DOI
10.1118/1.3181632

SU-FF-I-56: Radiation Dose Estimation From Pediatric Cone Beam Computed Tomography

Authors
Kim, S; Yoshizumi, T; Toncheva, G; Yin, F; Frush, D
MLA Citation
Kim, S, Yoshizumi, T, Toncheva, G, Yin, F, and Frush, D. "SU-FF-I-56: Radiation Dose Estimation From Pediatric Cone Beam Computed Tomography." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part3
Publish Date
2009
Start Page
2447
End Page
2447
DOI
10.1118/1.3181175

TH-A-211A-01: Digital Tomosynthesis for Target Localization

Authors
Yin, F; Wu, Q; Godfrey, D; Ren, L; Yoo, S; Maurer, J; Yan, H
MLA Citation
Yin, F, Wu, Q, Godfrey, D, Ren, L, Yoo, S, Maurer, J, and Yan, H. "TH-A-211A-01: Digital Tomosynthesis for Target Localization." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part26
Publish Date
2009
Start Page
2790
End Page
2791
DOI
10.1118/1.3182588

SU-FF-T-673: Application of RapidArc Technique to Cervical Spine Stereotactic Treatment

Authors
Brooks, A; Yin, F; Kirkpatrick, J; Wang, Z
MLA Citation
Brooks, A, Yin, F, Kirkpatrick, J, and Wang, Z. "SU-FF-T-673: Application of RapidArc Technique to Cervical Spine Stereotactic Treatment." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part19
Publish Date
2009
Start Page
2680
End Page
2680
DOI
10.1118/1.3182171

SU-FF-T-567: Volumetric Modulated Arc Therapy for Spine Body Radiotherapy: Comparison with Static Intensity Modulated Treatment

Authors
Wu, Q; Yoo, S; Kirkpatrick, J; McMahon, R; Thongphiew, D; Yin, F
MLA Citation
Wu, Q, Yoo, S, Kirkpatrick, J, McMahon, R, Thongphiew, D, and Yin, F. "SU-FF-T-567: Volumetric Modulated Arc Therapy for Spine Body Radiotherapy: Comparison with Static Intensity Modulated Treatment." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part18
Publish Date
2009
Start Page
2655
End Page
2655
DOI
10.1118/1.3182065

SU-FF-T-80: Hybrid Image Guided Radiation Therapy for Hypofractionated Prostate IMRT: Feasibility Study

Authors
Thongphiew, D; Zhu, X; Wu, Q; Wu, Q; Yin, F
MLA Citation
Thongphiew, D, Zhu, X, Wu, Q, Wu, Q, and Yin, F. "SU-FF-T-80: Hybrid Image Guided Radiation Therapy for Hypofractionated Prostate IMRT: Feasibility Study." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part9
Publish Date
2009
Start Page
2537
End Page
2538
DOI
10.1118/1.3181553

SU-FF-T-574: Radiotherapy Treatment Plans with RapidArc for Prostate Cancer Involving Seminal Vesicles

Authors
Yoo, S; Wu, Q; Lee, W; Yin, F
MLA Citation
Yoo, S, Wu, Q, Lee, W, and Yin, F. "SU-FF-T-574: Radiotherapy Treatment Plans with RapidArc for Prostate Cancer Involving Seminal Vesicles." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part18
Publish Date
2009
Start Page
2656
End Page
2656
DOI
10.1118/1.3182072

SU-FF-J-12: HU and Dosimetric Comparison of Six Cone-Beam CT Acquisition Techniques for Radiation Therapy Planning

Authors
Leeper, S; Yoo, S; Yin, FF
MLA Citation
Leeper, S, Yoo, S, and Yin, FF. "SU-FF-J-12: HU and Dosimetric Comparison of Six Cone-Beam CT Acquisition Techniques for Radiation Therapy Planning." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part5
Publish Date
2009
Start Page
2477
End Page
2477
DOI
10.1118/1.3181304

TU-C-303A-04: Slow Gantry Rotation Acquisition Protocol for Four-Dimensional Digital Tomosynthesis

Authors
Maurer, J; Pan, T; Yin, F
MLA Citation
Maurer, J, Pan, T, and Yin, F. "TU-C-303A-04: Slow Gantry Rotation Acquisition Protocol for Four-Dimensional Digital Tomosynthesis." June 2009.
Source
crossref
Published In
Medical physics
Volume
36
Issue
6Part22
Publish Date
2009
Start Page
2725
End Page
2725
DOI
10.1118/1.3182341

Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction.

This study compares three online image guidance techniques (IGRT) for prostate IMRT treatment: bony-anatomy matching, soft-tissue matching, and online replanning. Six prostate IMRT patients were studied. Five daily CBCT scans from the first week were acquired for each patient to provide representative "snapshots" of anatomical variations during the course of treatment. Initial IMRT plans were designed for each patient with seven coplanar 15 MV beams on a Eclipse treatment planning system. Two plans were created, one with a PTV margin of 10 mm and another with a 5 mm PTV margin. Based on these plans, the delivered dose distributions to each CBCT anatomy was evaluated to compare bony-anatomy matching, soft-tissue matching, and online replanning. Matching based on bony anatomy was evaluated using the 10 mm PTV margin ("bone10"). Soft-tissue matching was evaluated using both the 10 mm ("soft10") and 5 mm ("soft5") PTV margins. Online reoptimization was evaluated using the 5 mm PTV margin ("adapt"). The replanning process utilized the original dose distribution as the basis and linear goal programming techniques for reoptimization. The reoptimized plans were finished in less than 2 min for all cases. Using each IGRT technique, the delivered dose distribution was evaluated on all 30 CBCT scans (6 patients x 5 CBCT/patient). The mean minimum dose (in percentage of prescription dose) to the CTV over five treatment fractions were in the ranges of 99%-100% (SD = 0.1%-0.8%), 65%-98% (SD = 0.4%-19.5%), 87%-99% (SD = 0.7%-23.3%), and 95%-99% (SD = 0.4%-10.4%) for the adapt, bone10, soft5, and soft10 techniques, respectively. Compared to patient position correction techniques, the online reoptimization technique also showed improvement in OAR sparing when organ motion/deformations were large. For bladder, the adapt technique had the best (minimum) D90, D50, and D30 values for 24, 17, and 15 fractions out of 30 total fractions, while it also had the best D90, D50, and D30 values for the rectum for 25, 16, and 19 fractions, respectively. For cases where the adapt plans did not score the best for OAR sparing, the gains of the OAR sparing in the repositioning-based plans were accompanied by an underdosage in the target volume. To further evaluate the fast online replanning technique, a gold-standard plan ("new" plan) was generated for each CBCT anatomy on the Eclipse treatment planning system. The OAR sparing from the online replanning technique was compared to the new plan. The differences in D90, D50, and D30 of the OARs between the adapt and the new plans were less than 5% in 3 patients and were between 5% and 10% for the remaining three. In summary, all IGRT techniques could be sufficient to correct simple geometrical variations. However, when a high degree of deformation or differential organ position displacement occurs, the online reoptimization technique is feasible with less than 2 min optimization time and provides improvements in both CTV coverage and OAR sparing over the position correction techniques. For these cases, the reoptimization technique can be a highly valuable online IGRT tool to correct daily treatment uncertainties, especially when hypofractionation scheme is applied and daily correction, rather than averaging over many fractions, is required to match the original plan.

Authors
Thongphiew, D; Wu, QJ; Lee, WR; Chankong, V; Yoo, S; McMahon, R; Yin, F-F
MLA Citation
Thongphiew, D, Wu, QJ, Lee, WR, Chankong, V, Yoo, S, McMahon, R, and Yin, F-F. "Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction." Med Phys 36.5 (May 2009): 1651-1662.
PMID
19544782
Source
pubmed
Published In
Medical physics
Volume
36
Issue
5
Publish Date
2009
Start Page
1651
End Page
1662
DOI
10.1118/1.3095767

On-board SPECT for localizing functional targets: a simulation study.

Single photon emission computed tomography (SPECT) was investigated for imaging on-board radiation therapy machines in order to localize functional and molecular targets. A computer-simulated female NCAT phantom was positioned supine on a flat-top treatment couch. Twenty tumor locations were defined in the upper torso. The eight lung tumors were subject to the effects of respiratory motion. Tumor diameters of 10.8, 14.4, and 21.6 mm were simulated for tumor-to-background ratios of 3:1 and 6:1 that are characteristic of the radiotracer 99mTc-sestamibi. Projection images representing scan times of 4, 8, and 20 min were simulated for an anterior, half-circular trajectory. Images were reconstructed with attenuation correction by ordered-subsets expectation maximization (OSEM) using six subsets and five iterations. Contrast-to-noise ratios (CNRs) were calculated from ensembles of 25 images. Cross correlation with a noise-free tumor template was used to select the most suspicious tumor location within a 14.4-mm-radius search volume surrounding each tumor, with only that one tumor in each search volume. Localization accuracy was assessed by calculating average distances between measured and true tumor locations. Localization accuracy and CNRs were strongly affected by tumor location relative to the detector trajectory. For example, CNR values near the chest wall were greater by a factor of 3.5 than for tumors near the spine and posterior ribs, a much greater effect than the factor of 1.6 difference in CNR between 6:1 and 3:1 tumor uptakes. Typically, tumors of 6:1 uptake were localized as accurately with 4 min of scan time as tumors of 3:1 uptake that had been imaged for 20 min. Using 4 min scans, 14.4 and 21.6 mm anterior tumors of 6:1 uptake were localized within 2 mm. These results suggest that SPECT, on-board radiation therapy machines, may be a viable modality for localizing certain functional and molecular targets using relatively short scan times.

Authors
Roper, J; Bowsher, J; Yin, F-F
MLA Citation
Roper, J, Bowsher, J, and Yin, F-F. "On-board SPECT for localizing functional targets: a simulation study." Med Phys 36.5 (May 2009): 1727-1735.
PMID
19544790
Source
pubmed
Published In
Medical physics
Volume
36
Issue
5
Publish Date
2009
Start Page
1727
End Page
1735
DOI
10.1118/1.3113902

Stereotactic body radiotherapy for lesions of the spine and paraspinal regions.

PURPOSE: To describe our experience and clinical strategy for stereotactic body radiotherapy (SBRT) of spinal lesions. METHODS AND MATERIALS: Thirty-two patients with 33 spinal lesions underwent computed tomography-based simulation while free breathing. Gross/clinical target volumes included involved portions of the vertebral body and paravertebral/epidural tumor. Planning target volume (PTV) expansion was 6 mm axially and 3 mm radially; the cord was excluded from the PTV. Biologic equivalent dose was calculated using the linear quadratic model with alpha/beta = 3 Gy. Treatment was linear accelerator based with on-board imaging; dose was adjusted to maintain cord dose within tolerance. Survival, local control, pain, and neurologic status were monitored. RESULTS: Twenty-one patients are alive at 1 year (median survival, 14 months). Median follow-up is 6 months for all patients (7 months for survivors). Mean previous radiotherapy dose to 22 patients was 35 Gy, and median interval was 17 months. Renal (31%), breast, and lung (19% each) were the most common histologic sites. Three SBRT fractions (range, one to four fractions) of 7 Gy (range, 5-16 Gy) were delivered. Median cord and target biologic equivalent doses were 70 Gy(3) and 34.3 Gy(10), respectively. Thirteen patients reported complete and 17 patients reported partial pain relief at 1 month. There were four failures (mean, 5.8 months) with magnetic resonance imaging evidence of in-field progression. No dosimetric parameters predictive of failure were identified. No treatment-related toxicity was seen. CONCLUSIONS: Spinal SBRT is effective in the palliative/re-treatment setting. Volume expansion must ensure optimal PTV coverage while avoiding spinal cord toxicity. The long-term safety of spinal SBRT and the applicability of the linear-quadratic model in this setting remain to be determined, particularly the time-adjusted impact of prior radiotherapy.

Authors
Nelson, JW; Yoo, DS; Sampson, JH; Isaacs, RE; Larrier, NA; Marks, LB; Yin, F-F; Wu, QJ; Wang, Z; Kirkpatrick, JP
MLA Citation
Nelson, JW, Yoo, DS, Sampson, JH, Isaacs, RE, Larrier, NA, Marks, LB, Yin, F-F, Wu, QJ, Wang, Z, and Kirkpatrick, JP. "Stereotactic body radiotherapy for lesions of the spine and paraspinal regions." Int J Radiat Oncol Biol Phys 73.5 (April 1, 2009): 1369-1375.
PMID
19004569
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
73
Issue
5
Publish Date
2009
Start Page
1369
End Page
1375
DOI
10.1016/j.ijrobp.2008.06.1949

Ice as a water-equivalent solid medium for brachytherapy dosimetric measurements.

Precise positioning of source and dosimeters is essential in the experimental determination of dosimetric characteristics of brachytherapy sources. Various near-water equivalent solid phantoms have been used to achieve the necessary precision in the positioning. However, the uncertainties in their chemical compositions may lead to non-negligible uncertainties in the determined doses. It is proposed here that ice may be used as an alternative to the conventional solid phantoms, since its chemical composition is identical to water while the positioning advantage associated with solid phantoms is retained. In this work, the feasibility of using ice as a solid phantom for brachytherapy dosimetry is investigated. Ice-to-water conversion factors are calculated at distances of 0.2-10 cm from the source, for six high- and low-energy photon-emitting brachytherapy sources and mono-energetic photons between 10 keV to 2.0 MeV. Practical issues and challenges associated with measuring dose in an ice phantom are discussed.

Authors
Song, H; Chen, Z; Yue, N; Wu, Q; Yin, F-F
MLA Citation
Song, H, Chen, Z, Yue, N, Wu, Q, and Yin, F-F. "Ice as a water-equivalent solid medium for brachytherapy dosimetric measurements." Radiat Environ Biophys 48.2 (April 2009): 145-151.
PMID
19066926
Source
pubmed
Published In
Radiation and Environmental Biophysics
Volume
48
Issue
2
Publish Date
2009
Start Page
145
End Page
151
DOI
10.1007/s00411-008-0205-9

Tracking brachytherapy sources using emission imaging with one flat panel detector.

This work proposes to use the radiation from brachytherapy sources to track their dwell positions in three-dimensional (3D) space. The prototype device uses a single flat panel detector and a BB tray. The BBs are arranged in a defined pattern. The shadow of the BBs on the flat panel is analyzed to derive the 3D coordinates of the illumination source, i.e., the dwell position of the brachytherapy source. A kilovoltage x-ray source located 3.3 m away was used to align the center BB with the center pixel on the flat panel detector. For a test plan of 11 dwell positions, with an Ir-192 high dose rate unit, one projection was taken for each dwell point, and locations of the BB shadows were manually identified on the projection images. The 3D coordinates for the 11 dwell positions were reconstructed based on two BBs. The distances between dwell points were compared with the expected values. The average difference was 0.07 cm with a standard deviation of 0.15 cm. With automated BB shadow recognition in the future, this technique possesses the potential of tracking the 3D trajectory and the dwell times of a brachytherapy source in real time, enabling real time source position verification.

Authors
Song, H; Bowsher, J; Das, S; Yin, F-F
MLA Citation
Song, H, Bowsher, J, Das, S, and Yin, F-F. "Tracking brachytherapy sources using emission imaging with one flat panel detector." Med Phys 36.4 (April 2009): 1109-1111.
PMID
19472615
Source
pubmed
Published In
Medical physics
Volume
36
Issue
4
Publish Date
2009
Start Page
1109
End Page
1111
DOI
10.1118/1.3081402

Comparing digital tomosynthesis to cone-beam CT for position verification in patients undergoing partial breast irradiation.

PURPOSE: To evaluate digital tomosynthesis (DTS) technology for daily positioning of patients receiving accelerated partial breast irradiation (APBI) and to compare the positioning accuracy of DTS to three-dimensional cone-beam computed tomography (CBCT). METHODS AND MATERIALS: Ten patients who underwent APBI were scanned daily with on-board CBCT. A subset of the CBCT projections was used to reconstruct a stack of DTS image slices. To optimize soft-tissue visibility, the DTS images were reconstructed in oblique directions so that the tumor bed, breast tissue, ribs, and lungs were well separated. Coronal and sagittal DTS images were also reconstructed. Translational shifts of DTS images were obtained on different days from the same patients and were compared with the translational shifts of corresponding CBCT images. Seventy-seven CBCT scans and 291 DTS scans were obtained from nine evaluable patients. RESULTS: Tumor beds were best visible in the oblique DTS scans. One-dimensional positioning differences between DTS and CBCT images were 0.8-1.7 mm for the six patients with clips present and 1.2-2.0 mm for the three patients without clips. Because of the limited DTS scan angle, the DTS registration accuracy along the off-plane direction is lower than the accuracy along the in-plane directions. CONCLUSIONS: For patients receiving APBI, DTS localization offers comparable accuracy to CBCT localization for daily patient positioning while reducing mechanical constraints and imaging dose.

Authors
Zhang, J; Wu, QJ; Godfrey, DJ; Fatunase, T; Marks, LB; Yin, F-F
MLA Citation
Zhang, J, Wu, QJ, Godfrey, DJ, Fatunase, T, Marks, LB, and Yin, F-F. "Comparing digital tomosynthesis to cone-beam CT for position verification in patients undergoing partial breast irradiation." Int J Radiat Oncol Biol Phys 73.3 (March 1, 2009): 952-957.
PMID
19135316
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
73
Issue
3
Publish Date
2009
Start Page
952
End Page
957
DOI
10.1016/j.ijrobp.2008.10.036

Refinement of treatment setup and target localization accuracy using three-dimensional cone-beam computed tomography for stereotactic body radiotherapy.

PURPOSES: To quantitatively compare two-dimensional (2D) orthogonal kV with three-dimensional (3D) cone-beam CT (CBCT) for target localization; and to assess intrafraction motion with kV images in patients undergoing stereotactic body radiotherapy (SBRT). METHODS AND MATERIALS: A total of 50 patients with 58 lesions received 178 fractions of SBRT. After clinical setup using in-room lasers and skin/cradle marks placed at simulation, patients were imaged and repositioned according to orthogonal kV/MV registration of bony landmarks to digitally reconstructed radiographs from the planning CT. A subsequent CBCT was registered to the planning CT using soft tissue information, and the resultant "residual error" was measured and corrected before treatment. Posttreatment 2D kV and/or 3D CBCT images were compared with pretreatment images to determine any intrafractional position changes. Absolute averages, statistical means, standard deviations, and root mean square (RMS) values of observed setup error were calculated. RESULTS: After initial setup to external marks with laser guidance, 2D kV images revealed vector mean setup deviations of 0.67 cm (RMS). Cone-beam CT detected residual setup deviations of 0.41 cm (RMS). Posttreatment imaging demonstrated intrafractional variations of 0.15 cm (RMS). The individual shifts in three standard orthogonal planes showed no obvious directional biases. CONCLUSIONS: After localization based on superficial markings in patients undergoing SBRT, orthogonal kV imaging detects setup variations of approximately 3 to 4 mm in each direction. Cone-beam CT detects residual setup variations of approximately 2 to 3 mm.

Authors
Wang, Z; Nelson, JW; Yoo, S; Wu, QJ; Kirkpatrick, JP; Marks, LB; Yin, F-F
MLA Citation
Wang, Z, Nelson, JW, Yoo, S, Wu, QJ, Kirkpatrick, JP, Marks, LB, and Yin, F-F. "Refinement of treatment setup and target localization accuracy using three-dimensional cone-beam computed tomography for stereotactic body radiotherapy." Int J Radiat Oncol Biol Phys 73.2 (February 1, 2009): 571-577.
PMID
19147021
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
73
Issue
2
Publish Date
2009
Start Page
571
End Page
577
DOI
10.1016/j.ijrobp.2008.09.040

Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions.

BACKGROUND: This study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5 mm) for three groups of tumors -- spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size and shape. METHODS: Fifteen cases (5 for each site) were studied retrospectively. All lesions either abutted or were an integral part of critical structures (brainstem, liver or spinal cord). For brain and liver lesions, treatment plans using a 3D-conformal static technique (3D), dynamic conformal arcs (DARC) or intensity modulation (IMRT) were designed with a conventional linear accelerator with standard 5 mm leaf width multi-leaf collimator, and a linear accelerator dedicated for radiosurgery and hypofractionated therapy with a 2.5 mm leaf width collimator. For the concave spine lesions, intensity modulation was required to provide adequate conformality; hence, only IMRT plans were evaluated using either the standard or small leaf-width collimators.A total of 70 treatment plans were generated and each plan was individually optimized according to the technique employed. The Generalized Estimating Equation (GEE) was used to separate the impact of treatment technique from the MLC system on plan outcome, and t-tests were performed to evaluate statistical differences in target coverage and organ sparing between plans. RESULTS: The lesions ranged in size from 2.6 to 12.5 cc, 17.5 to 153 cc, and 20.9 to 87.7 cc for the brain, liver, and spine groups, respectively. As a group, brain lesions were smaller than spine and liver lesions. While brain and liver lesions were primarily ellipsoidal, spine lesions were more complex in shape, as they were all concave. Therefore, the brain and the liver groups were compared for volume effect, and the liver and spine groups were compared for shape. For the brain and liver groups, both the radiosurgery MLC and the IMRT technique contributed to the dose sparing of organs-at-risk(OARs), as dose in the high-dose regions of these OARs was reduced up to 15%, compared to the non-IMRT techniques employing a 5 mm leaf-width collimator. Also, the dose reduction contributed by the fine leaf-width MLC decreased, as dose savings at all levels diminished from 4 - 11% for the brain group to 1 - 5% for the liver group, as the target structures decreased in volume. The fine leaf-width collimator significantly improved spinal cord sparing, with dose reductions of 14 - 19% in high to middle dose regions, compared to the 5 mm leaf width collimator. CONCLUSION: The fine leaf-width MLC in combination with the IMRT technique can yield dosimetric benefits in radiosurgery and hypofractionated radiotherapy. Treatment of small lesions in cases involving complex target/OAR geometry will especially benefit from use of a fine leaf-width MLC and the use of IMRT.

Authors
Wu, QJ; Wang, Z; Kirkpatrick, JP; Chang, Z; Meyer, JJ; Lu, M; Huntzinger, C; Yin, F-F
MLA Citation
Wu, QJ, Wang, Z, Kirkpatrick, JP, Chang, Z, Meyer, JJ, Lu, M, Huntzinger, C, and Yin, F-F. "Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions. (Published online)" Radiat Oncol 4 (January 21, 2009): 3-.
PMID
19159471
Source
pubmed
Published In
Radiation Oncology
Volume
4
Publish Date
2009
Start Page
3
DOI
10.1186/1748-717X-4-3

Clinical evaluation of positioning verification using digital tomosynthesis and bony anatomy and soft tissues for prostate image-guided radiotherapy.

PURPOSE: To evaluate on-board digital tomosynthesis (DTS) for patient positioning vs. two-dimensional (2D) radiography and three-dimensional cone beam (CBCT). METHODS AND MATERIALS: A total of 92 image sessions from 9 prostate cancer patients were analyzed. An on-board image set was registered to a corresponding reference image set. Four pairs of image sets were used: digitally reconstructed radiographs vs. on-board orthogonal paired radiographs for the 2D method, coronal-reference DTS vs. on-board coronal DTS for the coronal-DTS method, sagittal-reference DTS vs. on-board sagittal DTS for the sagittal-DTS method, and planning CT vs. CBCT for the CBCT method. The registration results were compared. RESULTS: The systematic errors in all methods were <1 mm/1 degrees . When registering the bony anatomy, the mean vector difference was 0.21 +/- 0.11 cm between 2D and CBCT, 0.11 +/- 0.08 cm between CBCT and coronal DTS, and 0.14 +/- 0.07 cm between CBCT and sagittal DTS. The correlation between CBCT to DTS was stronger (coefficient = 0.92-0.95) than the correlation between 2D and CBCT or DTS (coefficient = 0.81-0.83). When registering the soft tissue, the mean vector difference was 0.18 +/- 0.11 cm between CBCT and coronal DTS and 0.29 +/- 0.17 cm between CBCT and sagittal DTS. The correlation coefficient of CBCT to sagittal DTS and to coronal DTS was 0.84 and 0.92, respectively. CONCLUSION: DTS could provide equivalent results to CBCT when the bony anatomy is used as landmarks for prostate image-guided radiotherapy. For soft tissue-based positioning verification, coronal DTS produced equivalent results to CBCT, but sagittal DTS alone was insufficient. DTS could allow for comparable soft tissue-based target localization with faster scanning time and a lower imaging dose compared with CBCT.

Authors
Yoo, S; Wu, QJ; Godfrey, D; Yan, H; Ren, L; Das, S; Lee, WR; Yin, F-F
MLA Citation
Yoo, S, Wu, QJ, Godfrey, D, Yan, H, Ren, L, Das, S, Lee, WR, and Yin, F-F. "Clinical evaluation of positioning verification using digital tomosynthesis and bony anatomy and soft tissues for prostate image-guided radiotherapy." Int J Radiat Oncol Biol Phys 73.1 (January 1, 2009): 296-305.
PMID
19100923
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
73
Issue
1
Publish Date
2009
Start Page
296
End Page
305
DOI
10.1016/j.ijrobp.2008.09.006

Efficient multiple acquisitions by Skipped Phase Encoding and Edge Deghosting (SPEED) using shared spatial information.

The fast MRI method of Skipped Phase Encoding and Edge Deghosting (SPEED) is further developed to accelerate multiple acquisitions. In a single acquisition, SPEED first acquires three sparse ghosted edge maps with an undersampling factor of N/3, which are modeled with a double-layer structure and described by three equations with two unknown ghosts, each with a unique ghost order index. By minimizing least-square-error, a pair of ghost order indexes is determined. Based on them, the two corresponding ghosts are resolved, leading to a deghosted image. In this case, three equations are needed to determine the ghost order index, while only two equations are required to resolve the two ghosts. This shows both inefficiency and potential. Multiple acquisitions often contain similar spatial information. The similarities can be used to improve efficiency by sharing the ghost order index among different acquisitions, leading to acceleration factors greater than that achievable with single acquisition.

Authors
Chang, Z; Xiang, Q-S; Ji, J; Yin, F-F
MLA Citation
Chang, Z, Xiang, Q-S, Ji, J, and Yin, F-F. "Efficient multiple acquisitions by Skipped Phase Encoding and Edge Deghosting (SPEED) using shared spatial information." Magn Reson Med 61.1 (January 2009): 229-233.
PMID
19097227
Source
pubmed
Published In
Magnetic Resonance in Medicine
Volume
61
Issue
1
Publish Date
2009
Start Page
229
End Page
233
DOI
10.1002/mrm.21809

Evaluating the Commissioning and QA of Intensity Modulated Arc Therapy using a Benchmark IMRT Planning Suite

Authors
McMahon, R; Xiao, Y; Ezzell, G; Wu, J; Yin, F
MLA Citation
McMahon, R, Xiao, Y, Ezzell, G, Wu, J, and Yin, F. "Evaluating the Commissioning and QA of Intensity Modulated Arc Therapy using a Benchmark IMRT Planning Suite." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S725
End Page
S725

Slow Gantry Rotation 4D Digital Tomosynthesis for Lung Motion Imaging

Authors
Maurer, JM; Pan, T; Yin, F
MLA Citation
Maurer, JM, Pan, T, and Yin, F. "Slow Gantry Rotation 4D Digital Tomosynthesis for Lung Motion Imaging." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S24
End Page
S24

Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions.

BACKGROUND: This study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5 mm) for three groups of tumors -- spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size and shape. METHODS: Fifteen cases (5 for each site) were studied retrospectively. All lesions either abutted or were an integral part of critical structures (brainstem, liver or spinal cord). For brain and liver lesions, treatment plans using a 3D-conformal static technique (3D), dynamic conformal arcs (DARC) or intensity modulation (IMRT) were designed with a conventional linear accelerator with standard 5 mm leaf width multi-leaf collimator, and a linear accelerator dedicated for radiosurgery and hypofractionated therapy with a 2.5 mm leaf width collimator. For the concave spine lesions, intensity modulation was required to provide adequate conformality; hence, only IMRT plans were evaluated using either the standard or small leaf-width collimators.A total of 70 treatment plans were generated and each plan was individually optimized according to the technique employed. The Generalized Estimating Equation (GEE) was used to separate the impact of treatment technique from the MLC system on plan outcome, and t-tests were performed to evaluate statistical differences in target coverage and organ sparing between plans. RESULTS: The lesions ranged in size from 2.6 to 12.5 cc, 17.5 to 153 cc, and 20.9 to 87.7 cc for the brain, liver, and spine groups, respectively. As a group, brain lesions were smaller than spine and liver lesions. While brain and liver lesions were primarily ellipsoidal, spine lesions were more complex in shape, as they were all concave. Therefore, the brain and the liver groups were compared for volume effect, and the liver and spine groups were compared for shape. For the brain and liver groups, both the radiosurgery MLC and the IMRT technique contributed to the dose sparing of organs-at-risk(OARs), as dose in the high-dose regions of these OARs was reduced up to 15%, compared to the non-IMRT techniques employing a 5 mm leaf-width collimator. Also, the dose reduction contributed by the fine leaf-width MLC decreased, as dose savings at all levels diminished from 4 - 11% for the brain group to 1 - 5% for the liver group, as the target structures decreased in volume. The fine leaf-width collimator significantly improved spinal cord sparing, with dose reductions of 14 - 19% in high to middle dose regions, compared to the 5 mm leaf width collimator. CONCLUSION: The fine leaf-width MLC in combination with the IMRT technique can yield dosimetric benefits in radiosurgery and hypofractionated radiotherapy. Treatment of small lesions in cases involving complex target/OAR geometry will especially benefit from use of a fine leaf-width MLC and the use of IMRT.

Authors
Wu, QJ; Wang, Z; Kirkpatrick, JP; Chang, Z; Meyer, JJ; Lu, M; Huntzinger, C; Yin, F-F
MLA Citation
Wu, QJ, Wang, Z, Kirkpatrick, JP, Chang, Z, Meyer, JJ, Lu, M, Huntzinger, C, and Yin, F-F. "Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions." Radiation oncology (London, England) 4 (2009): 3--.
Source
scival
Published In
Radiation Oncology
Volume
4
Publish Date
2009
Start Page
3-
DOI
10.1186/1748-717X-4-3

A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup

A positioning QA procedure for Varian's 2D/2D (kV/MV) and 3D/3D (planCT/CBCT) matching was developed. The procedure was to check: (1) the coincidence of on-board imager (OBI), portal imager (PI), and cone beam CT (CBCT)'s isocenters (digital graticules) to a linac's isocenter (to a pre-specified accuracy); (2) that the positioning difference detected by 2D/2D (kV/MV) and 3D/3D(planCT/CBCT) matching can be reliably transferred to couch motion. A cube phantom with a 2 mm metal ball (bb) at the center was used. The bb was used to define the isocenter. Two additional bbs were placed on two phantom surfaces in order to define a spatial location of 1.5 cm anterior, 1.5 cm inferior, and 1.5 cm right from the isocenter. An axial scan of the phantom was acquired from a multislice CT simulator. The phantom was set at the linac's isocenter (lasers); either AP MV/R Lat kV images or CBCT images were taken for 2D/2D or 3D/3D matching, respectively. For 2D/2D, the accuracy of each device's isocenter was obtained by checking the distance between the central bb and the digital graticule. Then the central bb in orthogonal DRRs was manually moved to overlay to the off-axis bbs in kV/MV images. For 3D/3D, CBCT was first matched to planCT to check the isocenter difference between the two CTs. Manual shifts were then made by moving CBCT such that the point defined by the two off-axis bbs overlay to the central bb in planCT. (PlanCT can not be moved in the current version of OBI1.4.) The manual shifts were then applied to remotely move the couch. The room laser was used to check the accuracy of the couch movement. For Trilogy (or Ix-21) linacs, the coincidence of imager and linac's isocenter was better than 1 mm (or 1.5 mm). The couch shift accuracy was better than 2 mm.

Authors
Guan, H; Hammoud, R; Yin, F-F
MLA Citation
Guan, H, Hammoud, R, and Yin, F-F. "A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup." Journal of Applied Clinical Medical Physics 10.4 (2009): 273-280.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
10
Issue
4
Publish Date
2009
Start Page
273
End Page
280

On-board SPECT Imaging: Improved Target Localization via Spatial Resolution Compensation

Authors
Roper, JR; Bowsher, JE; Yin, F
MLA Citation
Roper, JR, Bowsher, JE, and Yin, F. "On-board SPECT Imaging: Improved Target Localization via Spatial Resolution Compensation." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S574
End Page
S575

Development and Clinical Evaluation of a Novel 3D Digital Tomosynthesis (DTS) Reconstruction Method using a Deformation Field Map

Authors
Ren, L; Zhang, J; Thongphiew, D; Wu, Q; Yan, H; Brizel, DM; Lee, WR; Willett, CG; Yin, F
MLA Citation
Ren, L, Zhang, J, Thongphiew, D, Wu, Q, Yan, H, Brizel, DM, Lee, WR, Willett, CG, and Yin, F. "Development and Clinical Evaluation of a Novel 3D Digital Tomosynthesis (DTS) Reconstruction Method using a Deformation Field Map." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S96
End Page
S96

Six-dimensional Image Guidance for Spinal Noninvasive SRS/SBRT: Comparison between ExacTrac X-ray 6D with kV Cone-beam CT

Authors
Chang, Z; Wang, Z; Ma, J; O'Daniel, J; Kirkpatrick, J; Yin, F
MLA Citation
Chang, Z, Wang, Z, Ma, J, O'Daniel, J, Kirkpatrick, J, and Yin, F. "Six-dimensional Image Guidance for Spinal Noninvasive SRS/SBRT: Comparison between ExacTrac X-ray 6D with kV Cone-beam CT." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S125
End Page
S126

Imaging Guided Stereotactic Radiosurgery and its Accuracy Compared to Frame-based Localization

Authors
Wang, Z; Kirkpatrick, JP; Wu, QJ; Chang, Z; Willett, CG; Yin, F
MLA Citation
Wang, Z, Kirkpatrick, JP, Wu, QJ, Chang, Z, Willett, CG, and Yin, F. "Imaging Guided Stereotactic Radiosurgery and its Accuracy Compared to Frame-based Localization." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S690
End Page
S690

Can Biological Optimization Be Incorporated into the Current Clinical Treatment Planning Workflow?

Authors
Das, SK; Yin, F
MLA Citation
Das, SK, and Yin, F. "Can Biological Optimization Be Incorporated into the Current Clinical Treatment Planning Workflow?." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S625
End Page
S625

Hybrid IGRT Technique for Prostate Hypofractionation

Authors
Thongphiew, D; Zhu, X; Wu, QJ; Lee, WR; Wu, Q; Chankong, V; Yin, F
MLA Citation
Thongphiew, D, Zhu, X, Wu, QJ, Lee, WR, Wu, Q, Chankong, V, and Yin, F. "Hybrid IGRT Technique for Prostate Hypofractionation." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S648
End Page
S649

Treatment Plan Comparison between IMRT and Volumetric IMAT using One- and Two-arc Beams for Prostate Cancer

Authors
Yoo, S; Wu, J; Lee, WR; Yin, F
MLA Citation
Yoo, S, Wu, J, Lee, WR, and Yin, F. "Treatment Plan Comparison between IMRT and Volumetric IMAT using One- and Two-arc Beams for Prostate Cancer." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S707
End Page
S707

Apparatus-dependent Differences in Spine Stereotactic Body Radiosurgery (SBRT) Dosimetry

Authors
Ma, L; Cozzi, L; Larson, DA; Shiu, A; Letourneau, D; Yin, F; Chang, E; Sahgal, A
MLA Citation
Ma, L, Cozzi, L, Larson, DA, Shiu, A, Letourneau, D, Yin, F, Chang, E, and Sahgal, A. "Apparatus-dependent Differences in Spine Stereotactic Body Radiosurgery (SBRT) Dosimetry." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S676
End Page
S677

Calypso In Vivo Experience: Accuracy Compared to kV and CBCT Imaging and Analysis of Geometric Residual and Rotational Alignment

Authors
Courlas, LD; O'Daniel, JC; Wu, QJ; Lee, W; Yin, F
MLA Citation
Courlas, LD, O'Daniel, JC, Wu, QJ, Lee, W, and Yin, F. "Calypso In Vivo Experience: Accuracy Compared to kV and CBCT Imaging and Analysis of Geometric Residual and Rotational Alignment." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S584
End Page
S585

Quantitative Study of Geometrical Distortion in Cone-beam CT Images Reconstructed using FDK Algorithm

Authors
Zhuang, T; Li, H; Bowsher, J; Wang, Z; Yin, F
MLA Citation
Zhuang, T, Li, H, Bowsher, J, Wang, Z, and Yin, F. "Quantitative Study of Geometrical Distortion in Cone-beam CT Images Reconstructed using FDK Algorithm." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S604
End Page
S604

Comparison of Breath-hold with Amplitude-gating and Free-breathing Techniques for Stereotactic Body Radiation Therapy (SBRT) of Lung Cancers

Authors
Zhang, T; Yin, F; Wang, Z
MLA Citation
Zhang, T, Yin, F, and Wang, Z. "Comparison of Breath-hold with Amplitude-gating and Free-breathing Techniques for Stereotactic Body Radiation Therapy (SBRT) of Lung Cancers." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S670
End Page
S670

Comparing Static vs. Rotational IMRT for Spine Body Radiotherapy

Authors
Wu, Q; Kirkpatrick, J; Yon, S; McMahon, R; Thongphiew, D; Yin, F; Yin, F
MLA Citation
Wu, Q, Kirkpatrick, J, Yon, S, McMahon, R, Thongphiew, D, Yin, F, and Yin, F. "Comparing Static vs. Rotational IMRT for Spine Body Radiotherapy." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S672
End Page
S672

Evaluation of In-Room Cone-Beam CT Imaging Techniques Compared to CT for Dose Calculation

Authors
Leeper, SA; Yin, F; Yoo, S
MLA Citation
Leeper, SA, Yin, F, and Yoo, S. "Evaluation of In-Room Cone-Beam CT Imaging Techniques Compared to CT for Dose Calculation." 2009.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
75
Issue
3
Publish Date
2009
Start Page
S670
End Page
S671

Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging.

Real-time tracking can provide high accuracy localization for a moving target and minimize the effect of motion. Simultaneous kV-MV imaging has been proposed as a real-time tracking technique by utilizing the existing kV on-board imager (OBI) and the MV electronic portal device (EPID) mounted on the linear accelerator. The orthogonal pair of kV-MV images acquired simultaneously can provide 3-D localization in real-time. However, the kV and MV beams cross shooting the target interfere with each other with beam scattering, which affects the quality of images. The success of this modality heavily relies on the image quality, especially the visibility of the target, which was investigated in this study. The kV and MV images were acquired for a gold implant marker that was used as a surrogate of the target and placed in an IMRT thorax phantom, a dynamic phantom, and a pelvis phantom to test the image quality in different situations. Contrast-to-noise ration (CNR) was used to quantitatively describe the visibility of the target in the image. CNR can be obtained by statistical calculation from image processing and physics analysis with ion chamber measurement. The difference is described by contrast detection efficiency (CDE). By comparing the ratio (R) of CNR with and without the MV beam on, the MV beam scatter was found to have dramatically reduced the target visibility in the kV images (R=0.47), which was supported by an independent physics analysis that treats beam scatter as a noise. In contrast, the kV scatter effect on the MV images was minor (R=0.93). The effect of tumor motion was visible but tolerable for the target tracking purpose. CNR varied with different tumor sites and was lower for the pelvis than the thorax. Different kV imaging parameters such as kVp, mAs, and exposure time ms were tested for different cases. Considering a threshold of 1.0 CNR as a measure for the target visibility, a range of CNR from 1.3 to 4.2 was reached with appropriate tuning of those imaging parameters. This study has shown that CNR is a key parameter that can be used for assessing the visibility of the target in digital imaging and the quality of kV/MV images. It has also been shown that reasonable target visibility can be obtained using simultaneous kV-MV imaging for real-time target tracking.

Authors
Luo, W; Yoo, S; Wu, QJ; Wang, Z; Yin, F-F
MLA Citation
Luo, W, Yoo, S, Wu, QJ, Wang, Z, and Yin, F-F. "Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging." Med Phys 35.12 (December 2008): 5501-5509.
PMID
19175109
Source
pubmed
Published In
Medical physics
Volume
35
Issue
12
Publish Date
2008
Start Page
5501
End Page
5509
DOI
10.1118/1.3002313

Combining multiple models to generate consensus: application to radiation-induced pneumonitis prediction.

The fusion of predictions from disparate models has been used in several fields to obtain a more realistic and robust estimate of the "ground truth" by allowing the models to reinforce each other when consensus exists, or, conversely, negate each other when there is no consensus. Fusion has been shown to be most effective when the models have some complementary strengths arising from different approaches. In this work, we fuse the results from four common but methodologically different nonlinear multivariate models (Decision Trees, Neural Networks, Support Vector Machines, Self-Organizing Maps) that were trained to predict radiation-induced pneumonitis risk on a database of 219 lung cancer patients treated with radiotherapy (34 with Grade 2+ postradiotherapy pneumonitis). Each model independently incorporated a small number of features from the available set of dose and nondose patient variables to predict pneumonitis; no two models had all features in common. Fusion was achieved by simple averaging of the predictions for each patient from all four models. Since a model's prediction for a patient can be dependent on the patient training set used to build the model, the average of several different predictions from each model was used in the fusion (predictions were made by repeatedly testing each patient with a model built from different cross-validation training sets that excluded the patient being tested). The area under the receiver operating characteristics curve for the fused cross-validated results was 0.79, with lower variance than the individual component models. From the fusion, five features were extracted as the consensus among all four models in predicting radiation pneumonitis. Arranged in order of importance, the features are (1) chemotherapy; (2) equivalent uniform dose (EUD) for exponent a=1.2 to 3; (3) EUD for a=0.5 to 1.2, lung volume receiving >20-30 Gy; (4) female sex; and (5) squamous cell histology. To facilitate ease of interpretation and prospective use, the fused outcome results for the patients were fitted to a logistic probability function.

Authors
Das, SK; Chen, S; Deasy, JO; Zhou, S; Yin, F-F; Marks, LB
MLA Citation
Das, SK, Chen, S, Deasy, JO, Zhou, S, Yin, F-F, and Marks, LB. "Combining multiple models to generate consensus: application to radiation-induced pneumonitis prediction." Med Phys 35.11 (November 2008): 5098-5109.
PMID
19070244
Source
pubmed
Published In
Medical physics
Volume
35
Issue
11
Publish Date
2008
Start Page
5098
End Page
5109
DOI
10.1118/1.2996012

Dosimetric characteristics of novalis Tx system with high definition multileaf collimator.

A new Novalis Tx system equipped with a high definition multileaf collimator (HDMLC) recently became available to perform both image-guided radiosurgery and conventional radiotherapy. It is capable of delivering a highly conformal radiation dose with three energy modes: 6 MV photon energy, 15 MV photon energy, and 6 MV photon energy in a stereotactic radiosurgery mode with 1000 MU/min dose rate. Dosimetric characteristics of the new Novalis Tx treatment unit with the HDMLC are systematically measured for commissioning. A high resolution diode detector and miniion-chamber detector are used to measure dosimetric data for a range of field sizes from 4 x 4 mm to 400 x 400 mm. The commissioned Novalis Tx system has passed the RPC stereotactic radiosurgery head phantom irradiation test. The Novalis Tx system not only expands its capabilities with three energy modes, but also achieves better beam conformity and sharer beam penumbra with HDMLC. Since there is little beam data information available for the new Novalis Tx system, we present in this work the dosimetric data of the new modality for reference and comparison.

Authors
Chang, Z; Wang, Z; Wu, QJ; Yan, H; Bowsher, J; Zhang, J; Yin, F-F
MLA Citation
Chang, Z, Wang, Z, Wu, QJ, Yan, H, Bowsher, J, Zhang, J, and Yin, F-F. "Dosimetric characteristics of novalis Tx system with high definition multileaf collimator." Med Phys 35.10 (October 2008): 4460-4463.
PMID
18975693
Source
pubmed
Published In
Medical physics
Volume
35
Issue
10
Publish Date
2008
Start Page
4460
End Page
4463
DOI
10.1118/1.2977668

DOSIMETRIC AND RADIOBIOLOGICAL IMPACT OF A HIGH-DEFINITION MICROMULTILEAF COLLIMATOR ON RADIOSURGERY OF VESTIBULAR SCHWANNOMAS

Authors
Meyer, J; Wu, QJ; Sampson, J; Yin, F-F; Tucci, D; David, B; Zhiheng, W; Kirkpatrick, J
MLA Citation
Meyer, J, Wu, QJ, Sampson, J, Yin, F-F, Tucci, D, David, B, Zhiheng, W, and Kirkpatrick, J. "DOSIMETRIC AND RADIOBIOLOGICAL IMPACT OF A HIGH-DEFINITION MICROMULTILEAF COLLIMATOR ON RADIOSURGERY OF VESTIBULAR SCHWANNOMAS." October 2008.
Source
wos-lite
Published In
Neuro-Oncology
Volume
10
Issue
5
Publish Date
2008
Start Page
890
End Page
890

On-board four-dimensional digital tomosynthesis: first experimental results.

The purpose of this study is to propose four-dimensional digital tomosynthesis (4D-DTS) for on-board analysis of motion information in three dimensions. Images of a dynamic motion phantom were reconstructed using acquisition scan angles ranging from 20 degrees (DTS) to full 360 degrees cone-beam computed tomography (CBCT). Projection images were acquired using an on-board imager mounted on a clinical linear accelerator. Three-dimensional (3D) images of the moving target were reconstructed for various scan angles. 3D respiratory correlated phase images were also reconstructed. For phase-based image reconstructions, the trajectory of a radiopaque marker was tracked in projection space and used to retrospectively assign respiratory phases to projections. The projections were then sorted according phase and used to reconstruct motion correlated images. By using two sets of projections centered about anterior-posterior and lateral axes, this study demonstrates how phase resolved coronal and sagittal DTS images can be used to obtain 3D motion information. Motion artifacts in 4D-DTS phase images are compared with those present in four-dimensional CT (4DCT) images. Due to the nature of data acquisition for the two modalities, superior-inferior motion artifacts are suppressed to a greater extent in 4D-DTS images compared with 4DCT. Theoretical derivations and experimental results are presented to demonstrate how optimal selection of image acquisition parameters including the frequency of projection acquisition and the phase window depend on the respiratory period. Two methods for acquiring projections are discussed. Preliminary results indicate that 4D-DTS can be used to acquire valuable kinetic information of internal anatomy just prior to radiation treatment.

Authors
Maurer, J; Godfrey, D; Wang, Z; Yin, F-F
MLA Citation
Maurer, J, Godfrey, D, Wang, Z, and Yin, F-F. "On-board four-dimensional digital tomosynthesis: first experimental results." Med Phys 35.8 (August 2008): 3574-3583.
PMID
18777918
Source
pubmed
Published In
Medical physics
Volume
35
Issue
8
Publish Date
2008
Start Page
3574
End Page
3583
DOI
10.1118/1.2953561

A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map.

We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous cone-beam CT (CBCT) or planning CT data are used as the prior information, and the new patient volume to be reconstructed is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient DTS volume is then obtained by deforming the prior patient CBCT or CT volume according to the solution to the deformation field. This method is novel because it is the first method to combine deformable registration with limited angle image reconstruction. The method was tested in 2D cases using simulated projections of a Shepp-Logan phantom, liver, and head-and-neck patient data. The accuracy of the reconstruction was evaluated by comparing both organ volume and pixel value differences between DTS and CBCT images. In the Shepp-Logan phantom study, the reconstructed pixel signal-to-noise ratio (PSNR) for the 60° DTS image reached 34.3dB. In the liver patient study, the relative error of the liver volume reconstructed using 60° projections was 3.4%. The reconstructed PSNR for the 60° DTS image reached 23.5dB. In the head-and-neck patient study, the new method using 60° projections was able to reconstruct the 8.1° rotation of the bony structure with 0.0° error. The reconstructed PSNR for the 60° DTS image reached 24.2dB. In summary, the new reconstruction method can optimally estimate the volumetric information in DTS images using 60° projections. Preliminary validation of the algorithm showed that it is both technically and clinically feasible for image guidance in radiation therapy.

Authors
Ren, L; Zhang, J; Thongphiew, D; Godfrey, DJ; Wu, QJ; Zhou, S-M; Yin, F-F
MLA Citation
Ren, L, Zhang, J, Thongphiew, D, Godfrey, DJ, Wu, QJ, Zhou, S-M, and Yin, F-F. "A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map." Medical physics 35.7Part1 (July 2008): 3110-3115. (Letter)
PMID
28513030
Source
epmc
Published In
Medical physics
Volume
35
Issue
7Part1
Publish Date
2008
Start Page
3110
End Page
3115
DOI
10.1118/1.2940725

A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map.

We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous cone-beam CT (CBCT) or planning CT data are used as the prior information, and the new patient volume to be reconstructed is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient DTS volume is then obtained by deforming the prior patient CBCT or CT volume according to the solution to the deformation field. This method is novel because it is the first method to combine deformable registration with limited angle image reconstruction. The method was tested in 2D cases using simulated projections of a Shepp-Logan phantom, liver, and head-and-neck patient data. The accuracy of the reconstruction was evaluated by comparing both organ volume and pixel value differences between DTS and CBCT images. In the Shepp-Logan phantom study, the reconstructed pixel signal-to-noise ratio (PSNR) for the 60 degrees DTS image reached 34.3 dB. In the liver patient study, the relative error of the liver volume reconstructed using 60 degrees projections was 3.4%. The reconstructed PSNR for the 60 degrees DTS image reached 23.5 dB. In the head-and-neck patient study, the new method using 60 degrees projections was able to reconstruct the 8.1 degrees rotation of the bony structure with 0.0 degrees error. The reconstructed PSNR for the 60 degrees DTS image reached 24.2 dB. In summary, the new reconstruction method can optimally estimate the volumetric information in DTS images using 60 degrees projections. Preliminary validation of the algorithm showed that it is both technically and clinically feasible for image guidance in radiation therapy.

Authors
Ren, L; Zhang, J; Thongphiew, D; Godfrey, DJ; Wu, QJ; Zhou, S-M; Yin, F-F
MLA Citation
Ren, L, Zhang, J, Thongphiew, D, Godfrey, DJ, Wu, QJ, Zhou, S-M, and Yin, F-F. "A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map." Med Phys 35.7 (July 2008): 3110-3115. (Letter)
PMID
18697536
Source
pubmed
Published In
Medical physics
Volume
35
Issue
7
Publish Date
2008
Start Page
3110
End Page
3115
DOI
10.1118/1.2940725

Evaluation of an electron Monte Carlo dose calculation algorithm for electron beam.

The electron Monte Carlo (eMC) dose calculation algorithm of the Eclipse treatment planning system is based heavily upon Monte Carlo simulation of the linac head and modeling of the linac beam characteristics with minimal measurement of beam data. Commissioning of the eMC algorithm on multiple identical linacs provided a unique opportunity to systematically evaluate the algorithm with actual measurements of clinically relevant beam and dose parameters. In this study, measured and eMC calculated dose distributions were compared both along and perpendicular to electron beam direction for electron energy/applicator/depth combination using measurement data from four Varian 21EX CLINAC linear accelerator (Varian Medical System, Palo Alto, CA). Cutout factors for sizes down to 3 x 3 cm were also compared. Comparisons between the measurement and the eMC calculated values show that the R90, R80, R50, and R10 values mostly agree within 3 mm. Measure and Calculated bremsstrahlung dose Dx correlates well statistically although eMC calculated Dx values are consistently smaller than the measured, with maximum discrepancy of 1% for the 20 MeV electron beams. Surface dose agrees mostly within 2%. Field width and penumbra agree mostly within 3mm. Calculation grid size is found to have a significant effect on the dose calculation. A grid size of 5 mm can produce erroneous dose distributions. Using a grid size of 2.5 mm and a 3% accuracy specified for the eMC to stop calculation iteration, the absolute output agrees with measurements within 3% for field sizes of 5 x 5 cm or larger. For cutout of 3 x 3 cm, however, the output disagreement can reach 8%. Our result indicate that eMC algorithm in Eclipse provides acceptable agreement with measurement data for most clinical situations. Calculation grid size of 2.5 mm or smaller is recommended.

Authors
Hu, YA; Song, H; Chen, Z; Zhou, S; Yin, F-F
MLA Citation
Hu, YA, Song, H, Chen, Z, Zhou, S, and Yin, F-F. "Evaluation of an electron Monte Carlo dose calculation algorithm for electron beam. (Published online)" J Appl Clin Med Phys 9.3 (June 23, 2008): 2720-.
PMID
18716583
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
3
Publish Date
2008
Start Page
2720

SU-GG-J-156: Quantitative Analysis of Onboard SPECT Imaging Using Compact Gamma Cameras

Authors
Roper, J; Bowsher, J; Yin, F
MLA Citation
Roper, J, Bowsher, J, and Yin, F. "SU-GG-J-156: Quantitative Analysis of Onboard SPECT Imaging Using Compact Gamma Cameras." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part8
Publish Date
2008
Start Page
2715
End Page
2715
DOI
10.1118/1.2961705

SU-GG-T-454: Localization Accuracy of Cone-Beam CT Guided Radiosurgery as Investigated Utilizing a Geometric Phantom

Authors
Wang, Z; Wu, Q; Chang, Z; Kirkpatrick, J; Yin, F
MLA Citation
Wang, Z, Wu, Q, Chang, Z, Kirkpatrick, J, and Yin, F. "SU-GG-T-454: Localization Accuracy of Cone-Beam CT Guided Radiosurgery as Investigated Utilizing a Geometric Phantom." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part16
Publish Date
2008
Start Page
2829
End Page
2829
DOI
10.1118/1.2962202

SU-GG-J-177: The Application of An ASi-Based EPID to Guide Intensity Modulated Radiation Therapy (IMRT) of Head-And-Neck Cancer

Authors
Chang, Z; Yoo, S; Wang, Z; Yin, F
MLA Citation
Chang, Z, Yoo, S, Wang, Z, and Yin, F. "SU-GG-J-177: The Application of An ASi-Based EPID to Guide Intensity Modulated Radiation Therapy (IMRT) of Head-And-Neck Cancer." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part8
Publish Date
2008
Start Page
2720
End Page
2720
DOI
10.1118/1.2961726

MO-D-351-07: A System to Dynamically Balance Dose Sparing Between Critical Structures in Intensity Modulated Radiation Therapy (IMRT)

Authors
Das, S; Marks, L; Yin, FF
MLA Citation
Das, S, Marks, L, and Yin, FF. "MO-D-351-07: A System to Dynamically Balance Dose Sparing Between Critical Structures in Intensity Modulated Radiation Therapy (IMRT)." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part19
Publish Date
2008
Start Page
2868
End Page
2868
DOI
10.1118/1.2962358

SU-GG-J-81: Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy

Authors
Zhou, S; Das, S; Yin, F; Yoo, S; Lee, W; Yan, H; Wu, Q; Wang, Z; Marks, L
MLA Citation
Zhou, S, Das, S, Yin, F, Yoo, S, Lee, W, Yan, H, Wu, Q, Wang, Z, and Marks, L. "SU-GG-J-81: Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part6
Publish Date
2008
Start Page
2697
End Page
2697
DOI
10.1118/1.2961631

SU-GG-J-119: Localization Accuracy of Target Verification System Using Digitial Tomosynthesis (DTS)

Authors
Yan, H; Ren, L; Godfrey, D; Yoo, S; Yin, F
MLA Citation
Yan, H, Ren, L, Godfrey, D, Yoo, S, and Yin, F. "SU-GG-J-119: Localization Accuracy of Target Verification System Using Digitial Tomosynthesis (DTS)." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part7
Publish Date
2008
Start Page
2706
End Page
2706
DOI
10.1118/1.2961668

SU-GG-I-53: The Impact of Scan Angles On the Visibility of Anatomy in On-Board Digital Tomosynthesis (DTS) Images for Head and Neck Cancer Patients: A Single-Observer Study

Authors
Ma, J; Wu, Q; Godfrey, D; Yan, H; Ren, L; Yin, F
MLA Citation
Ma, J, Wu, Q, Godfrey, D, Yan, H, Ren, L, and Yin, F. "SU-GG-I-53: The Impact of Scan Angles On the Visibility of Anatomy in On-Board Digital Tomosynthesis (DTS) Images for Head and Neck Cancer Patients: A Single-Observer Study." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part3
Publish Date
2008
Start Page
2654
End Page
2654
DOI
10.1118/1.2961451

TU-EE-A3-03: On-Board Four-Dimensional Digital Tomosynthesis (4D-DTS): Optimization of Respiratory Motion Dependent Acquisition and Reconstruction Parameters

Authors
Maurer, J; Godfrey, D; Wang, Z; Yin, F
MLA Citation
Maurer, J, Godfrey, D, Wang, Z, and Yin, F. "TU-EE-A3-03: On-Board Four-Dimensional Digital Tomosynthesis (4D-DTS): Optimization of Respiratory Motion Dependent Acquisition and Reconstruction Parameters." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part22
Publish Date
2008
Start Page
2912
End Page
2913
DOI
10.1118/1.2962619

TH-D-351-02: A Novel Digital Tomosynthesis (DTS) Reconstruction Method Using Prior Information and a Deformation Model

Authors
Ren, L; Zhang, J; Thongphiew, D; Godfrey, D; Zhou, S; Yin, F
MLA Citation
Ren, L, Zhang, J, Thongphiew, D, Godfrey, D, Zhou, S, and Yin, F. "TH-D-351-02: A Novel Digital Tomosynthesis (DTS) Reconstruction Method Using Prior Information and a Deformation Model." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part27
Publish Date
2008
Start Page
2989
End Page
2989
DOI
10.1118/1.2962923

SU-GG-T-53: Integrating An Online Adaptive IMRT Process to the Prostate IGRT

Authors
Wu, Q; Thongphiew, D; Wang, Z; Yin, F; Yoo, S; Lee, W
MLA Citation
Wu, Q, Thongphiew, D, Wang, Z, Yin, F, Yoo, S, and Lee, W. "SU-GG-T-53: Integrating An Online Adaptive IMRT Process to the Prostate IGRT." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part9
Publish Date
2008
Start Page
2738
End Page
2738
DOI
10.1118/1.2961803

SU-GG-T-54: On-Line Adaptive IMRT for Prostate Cancer

Authors
Thongphiew, D; Wu, Q; Lee, W; Chankong, V; Yin, F
MLA Citation
Thongphiew, D, Wu, Q, Lee, W, Chankong, V, and Yin, F. "SU-GG-T-54: On-Line Adaptive IMRT for Prostate Cancer." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part9
Publish Date
2008
Start Page
2738
End Page
2738
DOI
10.1118/1.2961804

SU-GG-J-47: Clinical Implementation of An Integrated System for Image-Guided Radiation Therapy (IGRT) and Adaptive Radiation Therapy (ART)

Authors
Yoo, S; Wu, Q; Yin, F
MLA Citation
Yoo, S, Wu, Q, and Yin, F. "SU-GG-J-47: Clinical Implementation of An Integrated System for Image-Guided Radiation Therapy (IGRT) and Adaptive Radiation Therapy (ART)." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part6
Publish Date
2008
Start Page
2689
End Page
2689
DOI
10.1118/1.2961605

SU-GG-T-538: Dosimetric Effect of Energy Spread of Proton Beams

Authors
Luo, W; Ma, C; Yin, F; Fan, J
MLA Citation
Luo, W, Ma, C, Yin, F, and Fan, J. "SU-GG-T-538: Dosimetric Effect of Energy Spread of Proton Beams." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part18
Publish Date
2008
Start Page
2848
End Page
2848
DOI
10.1118/1.2962287

SU-GG-T-255: Experimental Verification of Lung Tumor Dose with Radiochromic Film

Authors
Zhang, J; Yoo, S; Kim, S; Yin, F
MLA Citation
Zhang, J, Yoo, S, Kim, S, and Yin, F. "SU-GG-T-255: Experimental Verification of Lung Tumor Dose with Radiochromic Film." June 2008.
Source
crossref
Published In
Medical physics
Volume
35
Issue
6Part13
Publish Date
2008
Start Page
2783
End Page
2784
DOI
10.1118/1.2962007

[Characteristics and affecting factors of denitrifying phosphorus removal in two-sludge sequencing batch reactor].

The characteristics of denitrifying phosphorus removal in a lab-scale two-sludge anaerobic-anoxic/nitrification SBR (A2 NSBR) system were studied fed with domestic wastewater. The influence of some key operation parameters, like C/P, C/N, and HRT, were examined using parallel tests, pH, dissolved oxygen (DO) and redox potential (ORP) were monitored on line to validate whether they could be used as the control parameters for this denitrifying phosphorus removal process. Results indicated that P removal efficiency showed an increased trend on the whole with the increase of the C/P. When the influent C/P was greater than 19.39, good phosphorus removal efficiency was achieved. However, the phosphorus removal efficiency deteriorated once the influent C/P decreased less than 15.36. On the other hand, relatively good phosphorus removal efficiency could be maintained in the A2 NSBR system even at a low C/N ratio, though the denitrification efficiency decrease instead. It is also found that increasing the influent C/N increased the PHB amount stored by polyphosphate accumulating organisms (PAO) and therefore the ultimate denitrification and phosphorus removal efficiency were both improved. For an excessively high C/N, the incompletely reacted COD will be residual to anoxic stage. Thus, the pure denitrification reaction, which preferentially supports OHOs, becomes the dominant reaction. This decreases the amount of available electron acceptors for denitrifying polyphosphate accumulating organisms (DNPAOs) at the anoxic stage which eventually impacts the anoxic phosphorus removal capacity. In addition, since A2 NSBR has two completely independent SBR systems, it benefits to establish a process control system in terms of the parameters DO, ORP, and pH.

Authors
Wang, Y-Y; Peng, Y-Z; Yin, F-F; Li, J; Zhang, Y-K
MLA Citation
Wang, Y-Y, Peng, Y-Z, Yin, F-F, Li, J, and Zhang, Y-K. "[Characteristics and affecting factors of denitrifying phosphorus removal in two-sludge sequencing batch reactor]." Huan Jing Ke Xue 29.6 (June 2008): 1526-1532.
PMID
18763495
Source
pubmed
Published In
Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]
Volume
29
Issue
6
Publish Date
2008
Start Page
1526
End Page
1532

Fast reconstruction of digital tomosynthesis using on-board images.

Digital tomosynthesis (DTS) is a method to reconstruct pseudo three-dimensional (3D) volume images from two-dimensional x-ray projections acquired over limited scan angles. Compared with cone-beam computed tomography, which is frequently used for 3D image guided radiation therapy, DTS requires less imaging time and dose. Successful implementation of DTS for fast target localization requires the reconstruction process to be accomplished within tight clinical time constraints (usually within 2 min). To achieve this goal, substantial improvement of reconstruction efficiency is necessary. In this study, a reconstruction process based upon the algorithm proposed by Feldkamp, Davis, and Kress was implemented on graphics hardware for the purpose of acceleration. The performance of the novel reconstruction implementation was tested for phantom and real patient cases. The efficiency of DTS reconstruction was improved by a factor of 13 on average, without compromising image quality. With acceleration of the reconstruction algorithm, the whole DTS generation process including data preprocessing, reconstruction, and DICOM conversion is accomplished within 1.5 min, which ultimately meets clinical requirement for on-line target localization.

Authors
Yan, H; Godfrey, DJ; Yin, F-F
MLA Citation
Yan, H, Godfrey, DJ, and Yin, F-F. "Fast reconstruction of digital tomosynthesis using on-board images." Med Phys 35.5 (May 2008): 2162-2169.
PMID
18561691
Source
pubmed
Published In
Medical physics
Volume
35
Issue
5
Publish Date
2008
Start Page
2162
End Page
2169
DOI
10.1118/1.2896077

The application of distance transformation on parameter optimization of inverse planning in intensity-modulated radiation therapy.

In inverse planning for intensity-modulated radiation therapy (IMRT), the dose specification and related weighting factor of an objective function for involved organs is usually predefined by a single value and then iteratively optimized, subject to a set of dose-volume constraints. Because the actual dose distribution is essentially non-uniform and considerably affected by the geometric shape and distribution of the anatomic structures involved, the spatial information regarding those structures should be incorporated such that the predefined parameter distribution is made to approach the clinically expected distribution. Ideally, these parameter distributions should be predefined on a voxel basis in a manual method. However, such an approach is too time-consuming to be feasible in routine use. In the present study, we developed a computer-aided method to achieve the goal described above, producing a non-uniform parameter distribution based on spatial information about the anatomic structures involved. The method consists of two steps: Use distance transformation technique to calculate the distance distribution of the structures. Based on the distance distribution, produce the parameter distribution via a function guided by prior knowledge. We use two simulated cases to examine the effectiveness of the method. The results indicate that application of a non-uniform parameter distribution produced by distance transformation clearly improves dose-sparing of critical organs without compromising dose coverage of the planning target.

Authors
Yan, H; Yin, F-F
MLA Citation
Yan, H, and Yin, F-F. "The application of distance transformation on parameter optimization of inverse planning in intensity-modulated radiation therapy. (Published online)" J Appl Clin Med Phys 9.2 (April 16, 2008): 2750-.
PMID
18714279
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
2
Publish Date
2008
Start Page
2750

The investigation on the location effect of external markers in respiratory-gated radiotherapy.

PURPOSE: To investigate the effect of the marker placement on the correlation relationship between the motions of external markers and the internal target under different breathing patterns for several lung cancer patients. METHOD AND MATERIAL: To monitor and record simultaneous motions of internal target and associated surrogate markers during respiratory gated radiotherapy, an infrared camera system synchronized with a medical simulator was installed in our institute. Multiple external markers were placed on the patients' chest wall with proper geometrical arrangement in closely monitoring the motion of skin near tumor. The motion signals of three breathing sessions (free breathing, breath-holding, and free breathing after breath-holding) were recorded and the quality of correlation between them was analyzed. For a single marker motion, its correlation with the internal target was analyzed using cross-covariance function. For the multiple markers, their correlation with the internal target was analyzed based on additive model. RESULT: Seven patients undergoing radiotherapy with right upper or middle lobe lesions were enrolled in this study. Statistic analysis based on the internal-external motion signals shows that the effect of marker location on the quality of its correlation with the internal target is varied from patient to patient. There was no specific marker location where consistently demonstrated superior quality of correlation with the internal target motion over three breathing sessions for all patients. As the composite surrogate signal which was generated from the motions of multiple external markers was used to correlate the internal target motion, significant improvement of the quality of correlation was achieved. CONCLUSION: The correlation of external marker to the internal target could be influenced by several factors such as patient population, marker locations, and breathing patterns, considerably. The quality of correlation and predictability to the internal target furnished by a single external marker is inferior to that of the composite signal generated from multiple external markers. The use of composite signal shows great potential in improving the predictability of internal target motion and presents an effective way to track tumor more accurately.

Authors
Yan, H; Zhu, G; Yang, J; Lu, M; Ajlouni, M; Kim, JH; Yin, F-F
MLA Citation
Yan, H, Zhu, G, Yang, J, Lu, M, Ajlouni, M, Kim, JH, and Yin, F-F. "The investigation on the location effect of external markers in respiratory-gated radiotherapy. (Published online)" J Appl Clin Med Phys 9.2 (April 16, 2008): 2758-.
PMID
18714280
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
2
Publish Date
2008
Start Page
2758

The impact of respiratory motion and treatment technique on stereotactic body radiation therapy for liver cancer.

Stereotactic body radiation therapy (SBRT), which delivers a much higher fractional dose than conventional treatment in only a few fractions, is an effective treatment for liver metastases. For patients who are treated under free-breathing conditions, however, respiration-induced tumor motion in the liver is a concern. Limited clinical information is available related to the impact of tumor motion and treatment technique on the dosimetric consequences. This study evaluated the dosimetric deviations between planned and delivered SBRT dose in the presence of tumor motion for three delivery techniques: three-dimensional conformal static beams (3DCRT), dynamic conformal arc (DARC), and intensity-modulated radiation therapy (IMRT). Five cases treated with SBRT for liver metastases were included in the study, with tumor motions ranging from 0.5 to 1.75 cm. For each case, three different treatment plans were developed using 3DCRT, DARC, and IMRT. The gantry/multileaf collimator (MLC) motion in the DARC plans and the MLC motion in the IMRT plans were synchronized to the patient's respiratory motion. Retrospectively sorted four-dimensional computed tomography image sets were used to determine patient-organ motion and to calculate the dose delivered during each respiratory phase. Deformable registration, using thin-plate-spline models, was performed to encode the tumor motion and deformation and to register the dose-per-phase to the reference phase images. The different dose distributions resulting from the different delivery techniques and motion ranges were compared to assess the effect of organ motion on dose delivery. Voxel dose variations occurred mostly in the high gradient regions, typically between the target volume and normal tissues, with a maximum variation up to 20%. The greatest CTV variation of all the plans was seen in the IMRT technique with the largest motion range (D99: -8.9%, D95: -8.3%, and D90: -6.3%). The greatest variation for all 3DCRT plans was less than 2% for D95. Dose variations for DARC fell between the 3DCRT and IMRT techniques. The dose volume histogram variations for normal organs were negligible. Therefore, the IMRT technique may be a preferable treatment choice in cases where the target volume and critical organs are in close proximity, or when normal organ protection is a high priority, provided that motion effect for the target volume can be managed.

Authors
Wu, QJ; Thongphiew, D; Wang, Z; Chankong, V; Yin, F-F
MLA Citation
Wu, QJ, Thongphiew, D, Wang, Z, Chankong, V, and Yin, F-F. "The impact of respiratory motion and treatment technique on stereotactic body radiation therapy for liver cancer." Med Phys 35.4 (April 2008): 1440-1451.
PMID
18491539
Source
pubmed
Published In
Medical physics
Volume
35
Issue
4
Publish Date
2008
Start Page
1440
End Page
1451
DOI
10.1118/1.2839095

Integration of cone-beam CT in stereotactic body radiation therapy.

This report describes the technique and initial experience using cone beam CT (CBCT) for localization of treatment targets in patients undergoing stereotactic body radiation therapy (SBRT). Patients selected for SBRT underwent 3-D or 4-D CT scans in a customized immobilization cradle. GTV, CTV, ITV, and PTV were defined. Intensity-modulated radiation beams, multiple 3-D conformal beams, or dynamic conformal arcs were delivered using a Varian 21EX with 120-leaf MLC. CBCT images were obtained prior to each fraction, and registered to the planning CT by using soft tissue and bony structures to assure accurate isocenter localization. Patients were repositioned for treatment based on the CBCT images. Radiographic images (kV, MV, or CBCT) were taken before and after beam delivery to further assess set-up accuracy. Ten patients with lung, liver, and spine lesions received 29 fractions of treatment using this technique. The prescription doses ranged 1250 approximately 6000 cGy in 1 approximately 5 fractions. Compared to traditional 2-D matching using bony structures, CBCT corrects target deviation from 1 mm to 15 mm, with an average of 5 mm. Comparison of pre-treatment to post-treatment radiographic images demonstrated an average 2 mm deviation (ranging from 0-4 mm). Improved immobilization may enhance positioning accuracy. Typical total "in-room" times for the patients are approximately 1 hour. CBCT-guided SBRT is feasible and enhances setup accuracy using 3-D anatomical information.

Authors
Yin, F-F; Wang, Z; Yoo, S; Wu, QJ; Kirkpatrick, J; Larrier, N; Meyer, J; Willett, CG; Marks, LB
MLA Citation
Yin, F-F, Wang, Z, Yoo, S, Wu, QJ, Kirkpatrick, J, Larrier, N, Meyer, J, Willett, CG, and Marks, LB. "Integration of cone-beam CT in stereotactic body radiation therapy." Technol Cancer Res Treat 7.2 (April 2008): 133-139.
PMID
18345702
Source
pubmed
Published In
Technology in cancer research & treatment
Volume
7
Issue
2
Publish Date
2008
Start Page
133
End Page
139
DOI
10.1177/153303460800700206

Assessment of the residual error in soft tissue setup in patients undergoing partial breast irradiation: results of a prospective study using cone-beam computed tomography.

PURPOSE: On-board cone-beam computed tomography (CBCT) provides soft tissue information that may improve setup accuracy in patients undergoing accelerated partial breast irradiation (APBI). We used CBCT to assess the residual error in soft tissue after two-dimensional kV/MV alignment based on bony anatomy. We also assessed the dosimetric impact of this error. METHODS AND MATERIALS: Ten patients undergoing APBI were studied as part of an institutional review board-approved prospective trial. Patients were aligned based on skin/cradle marks plus orthogonal kV/MV images registered based on bony landmarks to digitally reconstructed radiographs from the planning CT. A subsequent CBCT was registered to the planning CT using soft tissue information. This "residual error" and its dosimetric impact was measured. RESULTS: The root-mean-square of the residual error was 3, 4, and 4 mm, in the right-left, anterior-posterior, and superior-inferior directions, respectively. The average vector sum was 6+/-2 mm. Average reductions in mean dose to the lumpectomy cavity, clinical target volume (CTV), and planning target volume were 0.1%, 0.4%, and 1%, respectively. The mean difference in the clinical target and planning target volumes that received 95% of the prescribed dose (V95) were 1% and 4%. CONCLUSIONS: In this initial study with a modest number of patients, the residual error in soft tissue was typically <5 mm, and with the field margins used, the resultant dosimetric consequences were modest. In patients immobilized in a customized cradle, setup using orthogonal kV images thus appears accurate and reproducible. The CBCT technique may have particular utility in patients with larger breast volumes or breast deformations. Further studies involving larger numbers of patients are needed to further assess the utility of CBCT.

Authors
Fatunase, T; Wang, Z; Yoo, S; Hubbs, JL; Prosnitz, RG; Yin, F-F; Marks, LB
MLA Citation
Fatunase, T, Wang, Z, Yoo, S, Hubbs, JL, Prosnitz, RG, Yin, F-F, and Marks, LB. "Assessment of the residual error in soft tissue setup in patients undergoing partial breast irradiation: results of a prospective study using cone-beam computed tomography." Int J Radiat Oncol Biol Phys 70.4 (March 15, 2008): 1025-1034.
PMID
17892919
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
70
Issue
4
Publish Date
2008
Start Page
1025
End Page
1034
DOI
10.1016/j.ijrobp.2007.07.2344

On-line re-optimization of prostate IMRT plans for adaptive radiation therapy.

For intermediate and high risk prostate cancer, both the prostate gland and seminal vesicles are included in the clinical target volume. Internal motion patterns of these two organs vary, presenting a challenge for adaptive treatment. Adaptive techniques such as isocenter repositioning and soft tissue alignment are effective when tumor volumes only exhibit translational shift, while direct re-optimization of the intensity-modulated radiation therapy (IMRT) plan maybe more desirable when extreme deformation or differential positioning changes of the organs occur. Currently, direct re-optimization of the IMRT plan using beamlet (or fluence map) has not been reported. In this study, we report a novel on-line re-optimization technique that can accomplish plan adjustment on-line. Deformable image registration is used to provide position variation information on each voxel along the three dimensions. The original planned dose distribution is used as the 'goal' dose distribution for adaptation and to ensure planning quality. Fluence maps are re-optimized via linear programming, and a plan solution can be achieved within 2 min. The feasibility of this technique is demonstrated with a clinical case with large deformation. Such on-line ART process can be highly valuable with hypo-fractionated prostate IMRT treatment.

Authors
Wu, QJ; Thongphiew, D; Wang, Z; Mathayomchan, B; Chankong, V; Yoo, S; Lee, WR; Yin, F-F
MLA Citation
Wu, QJ, Thongphiew, D, Wang, Z, Mathayomchan, B, Chankong, V, Yoo, S, Lee, WR, and Yin, F-F. "On-line re-optimization of prostate IMRT plans for adaptive radiation therapy." Phys Med Biol 53.3 (February 7, 2008): 673-691.
PMID
18199909
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
53
Issue
3
Publish Date
2008
Start Page
673
End Page
691
DOI
10.1088/0031-9155/53/3/011

Automatic registration between reference and on-board digital tomosynthesis images for positioning verification.

The authors developed a hybrid multiresolution rigid-body registration technique to automatically register reference digital tomosynthesis (DTS) images with on-board DTS images to guide patient positioning in radiation therapy. This hybrid registration technique uses a faster but less accurate static method to achieve an initial registration, followed by a slower but more accurate adaptive method to fine tune the registration. A multiresolution scheme is employed in the registration to further improve the registration accuracy, robustness, and efficiency. Normalized mutual information is selected as the criterion for the similarity measure and the downhill simplex method is used as the search engine. This technique was tested using image data both from an anthropomorphic chest phantom and from eight head-and-neck cancer patients. The effects of the scan angle and the region-of-interest (ROI) size on the registration accuracy and robustness were investigated. The necessity of using the adaptive registration method in the hybrid technique was validated by comparing the results of the static method and the hybrid method. With a 44 degrees scan angle and a large ROI covering the entire DTS volume, the average of the registration capture ranges in single-axis simulations was between -31 and +34 deg for rotations and between -89 and +78 mm for translations in the phantom study, and between -38 and +38 deg for rotations and between -58 and +65 mm for translations in the patient study. Decreasing the DTS scan angle from 44 degrees to 22 degrees mainly degraded the registration accuracy and robustness for the out-of-plane rotations. Decreasing the ROI size from the entire DTS volume to the volume surrounding the spinal cord reduced the capture ranges to between -23 and +18 deg for rotations and between -33 and +43 mm for translations in the phantom study, and between -18 and +25 deg for rotations and between -35 and +39 mm for translations in the patient study. Results also showed that the hybrid registration technique had much larger capture ranges than the static method alone in registering the out-of-plane rotations.

Authors
Ren, L; Godfrey, DJ; Yan, H; Wu, QJ; Yin, F-F
MLA Citation
Ren, L, Godfrey, DJ, Yan, H, Wu, QJ, and Yin, F-F. "Automatic registration between reference and on-board digital tomosynthesis images for positioning verification." Med Phys 35.2 (February 2008): 664-672.
PMID
18383688
Source
pubmed
Published In
Medical physics
Volume
35
Issue
2
Publish Date
2008
Start Page
664
End Page
672
DOI
10.1118/1.2831903

Clinical assessment and characterization of a dual tube kilovoltage X-ray localization system in the radiotherapy treatment room.

INTRODUCTION: Although flat-panel based X-ray imaging has been well tested in diagnostic radiology, its use as an image-guided-radiotherapy (IGRT) system in a treatment room is new and requires systematic assessment. MATERIALS AND METHODS: BrainLab Novalis IGRT system was used for this study. It consists of two floor mounted kV X-ray tubes projecting obliquely into two flat-panel detectors mounted on the ceiling. The system automatically fuses the 2D localization images with 3D simulation CT image to provide positioning guidance. The following characteristics of the system were studied: (1) Coincidence of the isocenters between the IGRT and Linac; (2) Image quality; (3) Exposure; (4) Linearity, uniformity and repeatability. RESULTS: (1) Localization accuracy and coincidence of the isocenters between the IGRT and Linac was better than 1-mm. (2) The spatial resolution was quantified using the relative modulation-transfer-function with f50=0.7-0.9 lp/mm. The variation of contrast-noise-ratio with technical settings was measured. (3) The maximal exposure of an image was less than 95 mR. An empirical relation between the exposure and the X-ray technical setting was derived. (4) The linearity, uniformity and repeatability of the system generally meet the requirements. CONCLUSION: The system can be safely and reliably used as a target localization device.

Authors
Lee, S-W; Jin, J-Y; Guan, H; Martin, F; Kim, JH; Yin, F-F
MLA Citation
Lee, S-W, Jin, J-Y, Guan, H, Martin, F, Kim, JH, and Yin, F-F. "Clinical assessment and characterization of a dual tube kilovoltage X-ray localization system in the radiotherapy treatment room. (Published online)" J Appl Clin Med Phys 9.1 (January 13, 2008): 2318-.
PMID
18449161
Source
pubmed
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
1
Publish Date
2008
Start Page
2318

Using patient data similarities to predict radiation pneumonitis via a self-organizing map.

This work investigates the use of the self-organizing map (SOM) technique for predicting lung radiation pneumonitis (RP) risk. SOM is an effective method for projecting and visualizing high-dimensional data in a low-dimensional space (map). By projecting patients with similar data (dose and non-dose factors) onto the same region of the map, commonalities in their outcomes can be visualized and categorized. Once built, the SOM may be used to predict pneumonitis risk by identifying the region of the map that is most similar to a patient's characteristics. Two SOM models were developed from a database of 219 lung cancer patients treated with radiation therapy (34 clinically diagnosed with Grade 2+ pneumonitis). The models were: SOM(all) built from all dose and non-dose factors and, for comparison, SOM(dose) built from dose factors alone. Both models were tested using ten-fold cross validation and Receiver Operating Characteristics (ROC) analysis. Models SOM(all) and SOM(dose) yielded ten-fold cross-validated ROC areas of 0.73 (sensitivity/specificity = 71%/68%) and 0.67 (sensitivity/specificity = 63%/66%), respectively. The significant difference between the cross-validated ROC areas of these two models (p < 0.05) implies that non-dose features add important information toward predicting RP risk. Among the input features selected by model SOM(all), the two with highest impact for increasing RP risk were: (a) higher mean lung dose and (b) chemotherapy prior to radiation therapy. The SOM model developed here may not be extrapolated to treatment techniques outside that used in our database, such as several-field lung intensity modulated radiation therapy or gated radiation therapy.

Authors
Chen, S; Zhou, S; Yin, F-F; Marks, LB; Das, SK
MLA Citation
Chen, S, Zhou, S, Yin, F-F, Marks, LB, and Das, SK. "Using patient data similarities to predict radiation pneumonitis via a self-organizing map." Phys Med Biol 53.1 (January 7, 2008): 203-216.
PMID
18182697
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
53
Issue
1
Publish Date
2008
Start Page
203
End Page
216
DOI
10.1088/0031-9155/53/1/014

Evaluation of Image Enhancement Method on Target Registration Using Cone Beam CT in Radiation Therapy.

An intensity based six-degree image registration algorithm between cone-beam CT (CBCT) and planning CT has been developed for image-guided radiation therapy (IGRT). CT images of an anthropomorphic chest phantom were acquired using conventional CT scanner and corresponding CBCT was reconstructed based on projection images acquired by an on-board imager (OBI). Both sets of images were initially registered to each other using attached fudicial markers to achieve a golden standard registration. Starting from this point, an offset was applied to one set of images, and the matching result was found by a gray-value based registration method. Finally, The registration error was evaluated by comparing the detected shifts with the known shift. Three window-level (WL) combinations commonly used for image enhancement were examined to investigate the effect of anatomical information of Bony only (B), Bone+Tissue (BT), and Bone+Tissue+Air (BTA) on the accuracy and robustness of gray-value based registration algorithm. Extensive tests were performed in searching for the attraction range of registration algorithm. The widest attraction range was achieved with the WL combination of BTA. The average attraction ranges of this combination were 73.3 mm and 81.6 degree in the translation and rotation dimensions, respectively, and the average registration errors were 0.15 mm and 0.32 degree. The WL combination of BT shows the secondary largest attraction ranges. The WL combination of B shows limited convergence property and its attraction range was the smallest among the three examined combinations (on average 33.3 mm and 25.0 degree). If two sets of 3D images in original size (512 × 512) were used, registration could be accomplished within 10~20 minutes by current algorithm, which is only acceptable for off-line reviewing purpose. As the size of image set reduced by a factor of 2~4, the registration time would be 2~4 minutes which is feasible for on-line target localization.

Authors
Yan, H; Lei, R; Wu, J; Di, F; Yin, F-F
MLA Citation
Yan, H, Lei, R, Wu, J, Di, F, and Yin, F-F. "Evaluation of Image Enhancement Method on Target Registration Using Cone Beam CT in Radiation Therapy." Clin Med Oncol 2 (2008): 289-299.
PMID
21892290
Source
pubmed
Published In
Clinical Medicine: Oncology
Volume
2
Publish Date
2008
Start Page
289
End Page
299

Use of the BrainLAB ExacTrac X-Ray 6D system in image-guided radiotherapy.

The ExacTrac X-Ray 6D image-guided radiotherapy (IGRT) system will be described and its performance evaluated. The system is mainly an integration of 2 subsystems: (1) an infrared (IR)-based optical positioning system (ExacTrac) and (2) a radiographic kV x-ray imaging system (X-Ray 6D). The infrared system consists of 2 IR cameras, which are used to monitor reflective body markers placed on the patient's skin to assist in patient initial setup, and an IR reflective reference star, which is attached to the treatment couch and can assist in couch movement with spatial resolution to better than 0.3 mm. The radiographic kV devices consist of 2 oblique x-ray imagers to obtain high-quality radiographs for patient position verification and adjustment. The position verification is made by fusing the radiographs with the simulation CT images using either 3 degree-of-freedom (3D) or 6 degree-of-freedom (6D) fusion algorithms. The position adjustment is performed using the infrared system according to the verification results. The reliability of the fusion algorithm will be described based on phantom and patient studies. The results indicated that the 6D fusion method is better compared to the 3D method if there are rotational deviations between the simulation and setup positions. Recently, the system has been augmented with the capabilities for image-guided positioning of targets in motion due to respiration and for gated treatment of those targets. The infrared markers provide a respiratory signal for tracking and gating of the treatment beam, with the x-ray system providing periodic confirmation of patient position relative to the gating window throughout the duration of the gated delivery.

Authors
Jin, J-Y; Yin, F-F; Tenn, SE; Medin, PM; Solberg, TD
MLA Citation
Jin, J-Y, Yin, F-F, Tenn, SE, Medin, PM, and Solberg, TD. "Use of the BrainLAB ExacTrac X-Ray 6D system in image-guided radiotherapy." Med Dosim 33.2 (2008): 124-134.
PMID
18456164
Source
pubmed
Published In
Medical Dosimetry
Volume
33
Issue
2
Publish Date
2008
Start Page
124
End Page
134
DOI
10.1016/j.meddos.2008.02.005

Comparison of radiation doses between cone beam CT and multi detector CT: TLD measurements.

In recent years, wide beam computed tomography (CT) technique has become standard in radiation oncology whereas there is little information about radiation dose assessments for the technique. A point dose measurement method was employed to assess the radiation doses of cone beams CT (CBCT) and multi detectors CT (MDCT). The radiation doses of both modalities were measured using thermoluminescence dosemeters (TLDs) in head and body CT phantoms. Four TLD chips were placed at the centre and each peripheral channel to measure the doses. From the measurements, the weighted CT dose index for CBCT (CTDI(w)(CBCT)) and volume CT dose index for MDCT (CTDI(vol)(MDCT)) were derived. In the results, the CTDI(w)(CBCT) was 89.7 +/- 4.0 mGy and the CTDI(vol)(MDCT) was 137.0 +/- 7.4 mGy for the head scan. For the body scan, they were 37.9 +/- 1.4 and 74.3 +/- 5.3 mGy, respectively. In conclusion, CTDI(w)(CBCT) for the head scan was 35% lower than CTDI(vol)(MDCT), and CTDI(w)(CBCT) for the body scan was also 49% lower than CTDI(vol)(MDCT).

Authors
Kim, S; Yoshizumi, TT; Toncheva, G; Yoo, S; Yin, F-F
MLA Citation
Kim, S, Yoshizumi, TT, Toncheva, G, Yoo, S, and Yin, F-F. "Comparison of radiation doses between cone beam CT and multi detector CT: TLD measurements." Radiat Prot Dosimetry 132.3 (2008): 339-345.
PMID
19074786
Source
pubmed
Published In
Radiation Protection Dosimetry
Volume
132
Issue
3
Publish Date
2008
Start Page
339
End Page
345
DOI
10.1093/rpd/ncn305

A phantom study on target localization accuracy using cone-beam computed tomography.

The purpose of this study is to evaluate the 3-dimensional target localization accuracy of cone-beam computed tomography (CBCT) using an on-board imager (OBI). An anthropomorphic pelvis phantom was used to simulate a range of offsets in the three translational directions and rotations around each of the three axes. After a translational or rotational offset was applied, a CBCT scan of the phantom was followed by image registration to detect the offsets in six degrees. The detected offsets were compared to the offset actually applied to give the detection error of the phantom position. Afterwards, the phantom was positioned by automatically moving the couch based on the detected offsets. A second CBCT scan followed by image registration was performed to give the residual error of the phantom positioning. On the average the detection errors and their standard deviations along the lateral, longitudinal and vertical axis are 0.3 ± 0.1, 0.3 ± 0.1 and 0.4 ± 0.1 mm respectively with respect to translational shifts ranging from 0 to 10 mm. The corresponding residual errors after positioning are 0.3 ± 0.1, 0.5 ± 0.1 and 0.3 ± 0.1 mm. For simulated rotational shifts ranging from 0 to 5 degrees, the average detection error and their standard deviation around lateral, longitudinal, and vertical axes are 0.1 ± 0.0, 0.2 ± 0.0, and 0.2 ± 0.0 degrees respectively. The residual errors after positioning are 0.4 ± 0.1, 0.6 ± 0.1, and 0.3 ± 0.1 mm along the lateral, longitudinal and vertical directions. These results indicate that target localization based on CBCT is capable of achieving sub-millimeter accuracy.

Authors
Yan, H; Zhang, L; Yin, F-F
MLA Citation
Yan, H, Zhang, L, and Yin, F-F. "A phantom study on target localization accuracy using cone-beam computed tomography." Clin Med Oncol 2 (2008): 501-510.
PMID
21892325
Source
pubmed
Published In
Clinical Medicine: Oncology
Volume
2
Publish Date
2008
Start Page
501
End Page
510

Decision fusion of machine learning models to predict radiotherapyinduced lung pneumonitis

Combining different machine learning models (decision fusion) has been shown to be an effective method for estimating the underlying physical mechanism by allowing the models to reinforce each other when consensus exists, or, conversely, negate each other when there is no consensus. To be effective, decision fusion requires that the different models provide some degree of complementary information. In this work, we fuse the results of four different machine learning models (Boosted Decision Trees, Neural Networks, Support Vector Machines, Self Organizing Maps) to predict the risk of lung pneumonitis in patients undergoing thoracic radiotherapy. Fusion was achieved by simple averaging of the 10-fold cross validated predictions for each patient from all four models. To reduce prediction dependence on the manner in which the data set was split, 10-fold cross-validation was repeated 100 times for random data splitting. The area under the receiver operating characteristics curve for the fused cross-validated results was 0.79, higher than the individual models and with (generally) lower variance. The fusion extracted three important features as the consensus among all four models in predicting radiation pneumonitis risk: chemotherapy prior to radiotherapy, equivalent Uniform Dose (EUD) for exponent a = 1.2 to 3, and female gender. The results show great promise for machine learning in radiotherapy outcomes modeling. © 2008 IEEE.

Authors
Das, SK; Chen, S; Deasy, JO; Zhou, S; Yin, F-F; Marks, LB
MLA Citation
Das, SK, Chen, S, Deasy, JO, Zhou, S, Yin, F-F, and Marks, LB. "Decision fusion of machine learning models to predict radiotherapyinduced lung pneumonitis." Proceedings - 7th International Conference on Machine Learning and Applications, ICMLA 2008 (2008): 545-550.
Source
scival
Published In
Proceedings - 7th International Conference on Machine Learning and Applications, ICMLA 2008
Publish Date
2008
Start Page
545
End Page
550
DOI
10.1109/ICMLA.2008.122

Response to comments by Dr. Luijik and Dr. Schippers

Authors
Zhou, SM; Hoppenworth, EJ; Das, SK; Wang, ZH; Sun, XJ; Yin, FF; Dewhirst, MW
MLA Citation
Zhou, SM, Hoppenworth, EJ, Das, SK, Wang, ZH, Sun, XJ, Yin, FF, and Dewhirst, MW. "Response to comments by Dr. Luijik and Dr. Schippers." Medical Physics 35.6 (2008): 2560--.
Source
scival
Published In
Medical physics
Volume
35
Issue
6
Publish Date
2008
Start Page
2560-
DOI
10.1118/1.2912367

Evaluation of an electron Monte Carlo dose calculation algorithm for electron beams

The electron Monte Carlo (eMC) dose calculation algorithm of the Eclipse treatment planning system is based heavily upon Monte Carlo simulation of the linac head and modeling of the linac beam characteristics with minimal measurement of beam data. Commissioning of the eMC algorithm on multiple identical linacs provided a unique opportunity to systematically evaluate the algorithm with actual measurements of clinically relevant beam and dose parameters. In this study, measured and eMC calculated dose distributions were compared both along and perpendicular to electron beam direction for electron energy/applicator/ depth combination using measurement data from four Varian CLINAC 21EX linear accelerators (Varian Medical Systems, Palo Alto, CA). Cutout factors for sizes down to 3 × 3 cm were also compared. Comparisons between the measurement and the eMC calculated values show that the R90, R80, R50, and R10 values mostly agree within 3 mm. Measure and calculated bremsstrahlung dose Dx correlates well statistically although eMC calculated Dx values are consistently smaller than the measured, with maximum discrepancy of 1% for the 20 MeV electron beams. Surface dose agrees mostly within 2%. Field width and penumbra agree mostly within 3 mm. Calculation grid size is found to have a significant effect on the dose calculation. A grid size of 5 mm can produce erroneous dose distributions. Using a grid size of 2.5 mm and a 3% accuracy specified for the eMC to stop calculation iteration, the absolute output agrees with measurements within 3% for field sizes of 5 × 5 cm or larger. For cutout of 3 × 3 cm, however, the output disagreement can reach 8%. Our results indicate that the eMC algorithm in Eclipse provides acceptable agreement with measurement data for most clinical situations. Calculation grid size of 2.5 mm or smaller is recommended.

Authors
Hu, YA; Song, H; Chen, Z; Zhou, S; Yin, F-F
MLA Citation
Hu, YA, Song, H, Chen, Z, Zhou, S, and Yin, F-F. "Evaluation of an electron Monte Carlo dose calculation algorithm for electron beams." Journal of Applied Clinical Medical Physics 9.3 (2008): 1-15.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
3
Publish Date
2008
Start Page
1
End Page
15

An on-line adaptive radiation therapy system for intensity modulated radiation therapy: An application of multi-objective optimization

Radiation therapy (RT) is a non-invasive and highly ekective treatment option for Prostate cancer. The goal is to deliver the prescription dose to the tumor (prostate) while minimizing the damages to the surrounding healthy organs namely bladder, rectum, and femoral heads. One major drawback of the conventional RT is that organ positions and shapes vary from day to day and that the original plan that is based on pre-treatment CT images may no longer be appropriate for treatment in subsequent sessions. The usual remedy is to include some margins surrounding the target when planning the treatment. Though this image guided radiation therapy technique allows in-room correction and can eliminate patient setup errors, the uncertainty due to organ deformation still remains. Performing a plan re-optimization will take about 30 minutes which makes it impractical to perform an online correction. In this paper, we develop an Adaptive Radiation Therapy (ART) system for online adaptive IMRT planning to compensate for the internal motion during the course of the prostate cancer treatment. It allows the treatment plan to be quickly modified based on the anatomy-of-the-day.

Authors
Thongphiew, D; Chankong, V; Yin, F-F; Wu, QJ
MLA Citation
Thongphiew, D, Chankong, V, Yin, F-F, and Wu, QJ. "An on-line adaptive radiation therapy system for intensity modulated radiation therapy: An application of multi-objective optimization." Journal of Industrial and Management Optimization 4.3 (2008): 453-475.
Source
scival
Published In
Journal of Industrial and Management Optimization
Volume
4
Issue
3
Publish Date
2008
Start Page
453
End Page
475

Application of distance transformation on parameter optimization of inverse planning in intensity-modulated radiation therapy

In inverse planning for intensity-modulated radiation therapy (IMRT), the dose specification and related weighting factor of an objective function for involved organs is usually predefined by a single value and then iteratively optimized, subject to a set of dose-volume constraints. Because the actual dose distribution is essentially non-uniform and considerably affected by the geometric shape and distribution of the anatomic structures involved, the spatial information regarding those structures should be incorporated such that the predefined parameter distribution is made to approach the clinically expected distribution. Ideally, these parameter distributions should be predefined on a voxel basis in a manual method. However, such an approach is too time-consuming to be feasible in routine use. In the present study, we developed a computer-aided method to achieve the goal described above, producing a non-uniform parameter distribution based on spatial information about the anatomic structures involved. The method consists of two steps: • Use distance transformation technique to calculate the distance distribution of the structures. • Based on the distance distribution, produce the parameter distribution via a conversion function guided by prior knowledge. We use two simulated cases to examine the effectiveness of the method. The results indicate that application of a non-uniform parameter distribution produced by distance transformation clearly improves dose-sparing of critical organs without compromising dose coverage of the planning target.

Authors
Yan, H; Yin, F-F
MLA Citation
Yan, H, and Yin, F-F. "Application of distance transformation on parameter optimization of inverse planning in intensity-modulated radiation therapy." Journal of Applied Clinical Medical Physics 9.2 (2008): 30-44.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
2
Publish Date
2008
Start Page
30
End Page
44

Investigation of the location effect of external markers in respiratory-gated radiotherapy

In 7 lung and breast cancer patients, we investigated the location effect of external markers on the correlation between the motions of external markers and of an internal target under various breathing patterns. Our department developed a tumor tracking system consisting of two infrared cameras and a medical simulator. Using the system, we monitored the simultaneous motions of tumor and external markers placed at various locations on a patient's skin and saved the results for offline analysis. We then used a cross-covariance approach to analyze the correlation between the motions of individual markers and of the tumor. Based on the additive model, we evaluated the predictability of tumor motion from the motions of the external markers. The effect of marker location on the correlation between the motions of the tumor and of the external markers varied widely from patient to patient. At no specific marker location did the surrogate signal consistently present superior correlation with tumor motion in 3 breathing sessions with 7 patients. When the composite external signal generated from multiple external motion signals was correlated with tumor motion, the quality of the correlation improved significantly. In most cases, the composite signal provided the best surrogate signal for correlating with tumor motion. Correlation between the motions of external markers and of a tumor may be affected by several factors, including patient characteristics, marker locations, and breathing pattern. A single external marker cannot provide sufficient and reliable tracking information for tumor motion. A composite signal generated from the motions of multiple external makers provides an excellent surrogate signal, which in this study demonstrated superior correlation with tumor motion as compared with the signal provided by an individual marker. A composite signal would be a more reliable way to track tumor motion during respiratory-gated radiotherapy.

Authors
Yan, H; Zhu, G; Yang, J; Ajlouni, M; Kim, JH; Yin, F-F
MLA Citation
Yan, H, Zhu, G, Yang, J, Ajlouni, M, Kim, JH, and Yin, F-F. "Investigation of the location effect of external markers in respiratory-gated radiotherapy." Journal of Applied Clinical Medical Physics 9.2 (2008): 57-68.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
2
Publish Date
2008
Start Page
57
End Page
68

Clinical assessment and characterization of a dual tube kilovoltage X-ray localization system in the radiotherapy treatment room

Although flat-panel kilovoltage X-ray imaging devices have been well tested for clinical use in diagnostic radiology, their use as a part of an image-guided radiation therapy (IGRT) system in a treatment room is new and requires systematic assessment. We used the Novalis IGRT system (BrainLAB, Feldkirchen, Germany) for the present study. The system consists of two floor-mounted kilovoltage X-ray tubes projecting obliquely onto two flat-panel detectors mounted on the ceiling. The system can automatically fuse two-dimensional localization images with three-dimensional simulation computed tomography images to provide positioning guidance. We evaluated these system parameters: • Overall performance of the IGRT system, including isocenter correlation between the IGRT system and the linear accelerator (LINAC) • Image quality of the system • Exposure received by patients for a pair of images • Linearity, uniformity, and repeatability of the system The Novalis system uses a daily isocenter calibration procedure to ensure consistency of isocenters between the IGRT and the LINAC systems. The localization accuracy was about 1 mm. We measured the relative modulation transfer function (RMTF) to quantify the spatial resolution of the imaging device, with f50 being 0.7-0.9 line pairs per millimeter. The maximal exposure of an image was 95 mR. We derived an empirical relationship between the exposure and the X-ray technical settings. The other parameters of the system were quantitatively measured and generally met the requirements. The IGRT system is safe and reliable for clinical use as a target localization device. The measured data can be used as a benchmark for a quality assurance procedure.

Authors
Lee, S-W; Jin, J-Y; Guan, H; Martin, F; Kim, JH; Yin, F-F
MLA Citation
Lee, S-W, Jin, J-Y, Guan, H, Martin, F, Kim, JH, and Yin, F-F. "Clinical assessment and characterization of a dual tube kilovoltage X-ray localization system in the radiotherapy treatment room." Journal of Applied Clinical Medical Physics 9.1 (2008): 1-15.
Source
scival
Published In
Journal of applied clinical medical physics / American College of Medical Physics
Volume
9
Issue
1
Publish Date
2008
Start Page
1
End Page
15

Are post-RT cardiac perfusion defects due to cardiac toxicity, or are they artifacts from attenuation changes in surrounding soft tissues?

Authors
Roper, J; Manzoor, A; Bowsher, J; Yin, F; Zhou, S; Wong, T; Borges-Neto, S; Hubbs, J; Demirci, S; Marks, L
MLA Citation
Roper, J, Manzoor, A, Bowsher, J, Yin, F, Zhou, S, Wong, T, Borges-Neto, S, Hubbs, J, Demirci, S, and Marks, L. "Are post-RT cardiac perfusion defects due to cardiac toxicity, or are they artifacts from attenuation changes in surrounding soft tissues?." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S518
End Page
S519
DOI
10.1016/j.ijrobp.2008.06.035

High-definition micro-multileaf collimator in radiosurgery treatment planning for arteriovenous malformations

Authors
Boyd, JA; Kim, DW; Meyer, JJ; Wang, Z; Britz, GW; Wu, J; Yin, F; Kirkpatrick, JP
MLA Citation
Boyd, JA, Kim, DW, Meyer, JJ, Wang, Z, Britz, GW, Wu, J, Yin, F, and Kirkpatrick, JP. "High-definition micro-multileaf collimator in radiosurgery treatment planning for arteriovenous malformations." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S531
End Page
S532
DOI
10.1016/j.ijrobp.2008.06.064

Dosimetrical evaluation of SRS/SBRT techniques

Authors
Wu, QJ; Wang, Z; Kirkpatrick, JP; Chang, Z; Zhou, S; Willett, CG; Yin, F
MLA Citation
Wu, QJ, Wang, Z, Kirkpatrick, JP, Chang, Z, Zhou, S, Willett, CG, and Yin, F. "Dosimetrical evaluation of SRS/SBRT techniques." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S650
End Page
S651
DOI
10.1016/j.ijrobp.2008.06.328

Can cone beam CT replace frame-based localization for stereotactic radiosurgery?

Authors
Wang, Z; Kirkpatrick, JP; Wu, QJ; Chang, Z; Willett, CG; Yin, F
MLA Citation
Wang, Z, Kirkpatrick, JP, Wu, QJ, Chang, Z, Willett, CG, and Yin, F. "Can cone beam CT replace frame-based localization for stereotactic radiosurgery?." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S534
End Page
S534
DOI
10.1016/j.ijrobp.2008.06.070

Can single photon emission computed tomography (SPECT) weighted "Functional" lung dose improve radiation pneumonitis prediction?

Authors
Das, SK; Chen, S; Zhou, S; Yin, F; Marks, LB
MLA Citation
Das, SK, Chen, S, Zhou, S, Yin, F, and Marks, LB. "Can single photon emission computed tomography (SPECT) weighted "Functional" lung dose improve radiation pneumonitis prediction?." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S66
End Page
S66
DOI
10.1016/j.ijrobp.2008.06.916

A novel digital tomosynthesis (DTS) reconstruction method using prior information and a deformation model

Authors
Ren, L; Zhang, J; Thongphiew, D; Wu, Q; Godfrey, DJ; Zhou, S; Yin, F
MLA Citation
Ren, L, Zhang, J, Thongphiew, D, Wu, Q, Godfrey, DJ, Zhou, S, and Yin, F. "A novel digital tomosynthesis (DTS) reconstruction method using prior information and a deformation model." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S109
End Page
S109
DOI
10.1016/j.ijrobp.2008.06.1014

Dosimetrical evaluation of an online adaptive IMRT technique

Authors
Thongphiew, D; Wu, QJ; Lee, WR; Yoo, S; Chankong, V; Yin, F
MLA Citation
Thongphiew, D, Wu, QJ, Lee, WR, Yoo, S, Chankong, V, and Yin, F. "Dosimetrical evaluation of an online adaptive IMRT technique." 2008.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
72
Issue
1
Publish Date
2008
Start Page
S562
End Page
S562
DOI
10.1016/j.ijrobp.2008.06.132

The impact of advanced technologies on treatment deviations in radiation treatment delivery.

PURPOSE: To assess the impact of new technologies on deviation rates in radiation therapy (RT). METHODS AND MATERIALS: Treatment delivery deviations in RT were prospectively monitored during a time of technology upgrade. In January 2003, our department had three accelerators, none with "modern" technologies (e.g., without multileaf collimators [MLC]). In 2003 to 2004, we upgraded to five new accelerators, four with MLC, and associated advanced capabilities. The deviation rates among patients treated on "high-technology" versus "low-technology" machines (defined as those with vs. without MLC) were compared over time using the two-tailed Fisher's exact test. RESULTS: In 2003, there was no significant difference between the deviation rate in the "high-technology" versus "low-technology" groups (0.16% vs. 0.11%, p = 0.45). In 2005 to 2006, the deviation rate for the "high-technology" groups was lower than the "low-technology" (0.083% vs. 0.21%, p = 0.009). This difference was caused by a decline in deviations on the "high-technology" machines over time (p = 0.053), as well as an unexpected trend toward an increase in deviations over time on the "low-technology" machines (p = 0.15). CONCLUSIONS: Advances in RT delivery systems appear to reduce the rate of treatment deviations. Deviation rates on "high-technology" machines with MLC decline over time, suggesting a learning curve after the introduction of new technologies. Associated with the adoption of "high-technology" was an unexpected increase in the deviation rate with "low-technology" approaches, which may reflect an over-reliance on tools inherent to "high-technology" machines. With the introduction of new technologies, continued diligence is needed to ensure that staff remain proficient with "low-technology" approaches.

Authors
Marks, LB; Light, KL; Hubbs, JL; Georgas, DL; Jones, EL; Wright, MC; Willett, CG; Yin, FF
MLA Citation
Marks, LB, Light, KL, Hubbs, JL, Georgas, DL, Jones, EL, Wright, MC, Willett, CG, and Yin, FF. "The impact of advanced technologies on treatment deviations in radiation treatment delivery." Int J Radiat Oncol Biol Phys 69.5 (December 1, 2007): 1579-1586.
PMID
18035214
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
69
Issue
5
Publish Date
2007
Start Page
1579
End Page
1586
DOI
10.1016/j.ijrobp.2007.08.017

Cone-beam CT localization of internal target volumes for stereotactic body radiotherapy of lung lesions.

PURPOSE: In this study, we investigate a technique of matching internal target volumes (ITVs) in four-dimensional (4D) simulation computed tomography (CT) to the composite target volume in free-breathing on-board cone-beam (CB) CT. The technique is illustrated by using both phantom and patient cases. METHODS AND MATERIALS: A dynamic phantom with a target ball simulating respiratory motion with various amplitude and cycle times was used to verify localization accuracy. The dynamic phantom was scanned using simulation CT with a phase-based retrospective sorting technique. The ITV was then determined based on 10 sets of sorted images. The size and epicenter of the ITV identified from 4D simulation CT images and the composite target volume identified from on-board CBCT images were compared to assess localization accuracy. Similarly, for two clinical cases of patients with lung cancer, ITVs defined from 4D simulation CT images and CBCT images were compared. RESULTS: For the phantom, localization accuracy between the ITV in 4D simulation CT and the composite target volume in CBCT was within 1 mm, and ITV was within 8.7%. For patient cases, ITVs on simulation CT and CBCT were within 8.0%. CONCLUSION: This study shows that CBCT is a useful tool to localize ITV for targets affected by respiratory motion. Verification of the ITV from 4D simulation CT using on-board free-breathing CBCT is feasible for the target localization of lung tumors.

Authors
Wang, Z; Wu, QJ; Marks, LB; Larrier, N; Yin, F-F
MLA Citation
Wang, Z, Wu, QJ, Marks, LB, Larrier, N, and Yin, F-F. "Cone-beam CT localization of internal target volumes for stereotactic body radiotherapy of lung lesions." Int J Radiat Oncol Biol Phys 69.5 (December 1, 2007): 1618-1624.
PMID
18035215
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
69
Issue
5
Publish Date
2007
Start Page
1618
End Page
1624
DOI
10.1016/j.ijrobp.2007.08.030

Intra-fraction motion during tangential treatment of the left breast: how consistently is the heart actually blocked?

Authors
Wang, Z; Yin, F-F; Maurer, J; Wu, QJ; Hubbs, J; Marks, LB
MLA Citation
Wang, Z, Yin, F-F, Maurer, J, Wu, QJ, Hubbs, J, and Marks, LB. "Intra-fraction motion during tangential treatment of the left breast: how consistently is the heart actually blocked?." December 2007.
Source
wos-lite
Published In
Breast Cancer Research and Treatment
Volume
106
Publish Date
2007
Start Page
S194
End Page
S194

On-board patient positioning for head-and-neck IMRT: comparing digital tomosynthesis to kilovoltage radiography and cone-beam computed tomography.

PURPOSE: High-precision intensity-modulated radiotherapy demands high patient positioning accuracy. On-board digital tomosynthesis (DTS) provides three-dimensional (3D) image guidance for daily positioning with a lower imaging dose, faster acquisition, and more geometric flexibility than 3D cone-beam computed tomography (CBCT). This clinical study evaluated DTS as a daily imaging technique for patient positioning and compared the results with 3D CBCT and two-dimensional (2D) radiography. METHODS AND MATERIALS: Head and neck cancer patients undergoing intensity-modulated radiotherapy were studied. For each session, the patient was positioned using laser marks. On-board imaging data sets, including 2D kilovoltage radiographs, DTS, and CBCT, were obtained to measure the daily patient positioning variations. The mean and standard deviations of the positioning variations in the translational and rotational directions were calculated. The positioning differences among 2D radiography, DTS, and CBCT were analyzed. RESULTS: Image data sets were collected from 65 treatment fractions for 10 patients. The systematic patient positioning variation was <0.10 cm and 1.0 degrees one dimensionally. The random variations were 0.27-0.34 cm in the translational and 0.93 degrees -1.99 degrees in the rotational direction. The mean vector isocenter variation was 0.48 cm. DTS with 40 degrees and 20 degrees scan angles in the coronal or sagittal directions yielded the same results for patient positioning. DTS performance was comparable to that of CBCT, with positioning differences of <0.1 cm and 0.5 degrees . The positioning difference between 2D radiography and DTS was approximately 0.1 cm and 0.2 cm in the vertical/longitudinal and lateral directions. CONCLUSION: Our results have demonstrated that DTS is a comparable 3D imaging technique to CBCT for daily patient positioning of head-and-neck patients as determined by manual registration of bony anatomy.

Authors
Wu, QJ; Godfrey, DJ; Wang, Z; Zhang, J; Zhou, S; Yoo, S; Brizel, DM; Yin, F-F
MLA Citation
Wu, QJ, Godfrey, DJ, Wang, Z, Zhang, J, Zhou, S, Yoo, S, Brizel, DM, and Yin, F-F. "On-board patient positioning for head-and-neck IMRT: comparing digital tomosynthesis to kilovoltage radiography and cone-beam computed tomography." Int J Radiat Oncol Biol Phys 69.2 (October 1, 2007): 598-606.
PMID
17869673
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
69
Issue
2
Publish Date
2007
Start Page
598
End Page
606
DOI
10.1016/j.ijrobp.2007.05.045

Investigation of the support vector machine algorithm to predict lung radiation-induced pneumonitis.

The purpose of this study is to build and test a support vector machine (SVM) model to predict for the occurrence of lung radiation-induced Grade 2+ pneumonitis. SVM is a sophisticated statistical technique capable of separating the two categories of patients (with/without pneumonitis) using a boundary defined by a complex hypersurface. Despite the complexity, the SVM boundary is only minimally influenced by outliers that are difficult to separate. By contrast, the simple hyperplane boundary computed by the more commonly used and related linear discriminant analysis method is heavily influenced by outliers. Two SVM models were built using data from 219 patients with lung cancer treated using radiotherapy (34 diagnosed with pneumonitis). One model (SVM(all)) selected input features from all dose and non-dose factors. For comparison, the other model (SVM(dose)) selected input features only from lung dose-volume factors. Model predictive ability was evaluated using ten-fold cross-validation and receiver operating characteristics (ROC) analysis. For the model SVM(all), the area under the cross-validated ROC curve was 0.76 (sensitivity/specificity = 74%/75%). Compared to the corresponding SVM(dose) area of 0.71 (sensitivity/specificity = 68%/68%), the predictive ability of SVM(all) was improved, indicating that non-dose features are important contributors to separating patients with and without pneumonitis. Among the input features selected by model SVM(all), the two with highest importance for predicting lung pneumonitis were: (a) generalized equivalent uniform doses close to the mean lung dose, and (b) chemotherapy prior to radiotherapy. The model SVM(all) is publicly available via internet access.

Authors
Chen, S; Zhou, S; Yin, F-F; Marks, LB; Das, SK
MLA Citation
Chen, S, Zhou, S, Yin, F-F, Marks, LB, and Das, SK. "Investigation of the support vector machine algorithm to predict lung radiation-induced pneumonitis." Med Phys 34.10 (October 2007): 3808-3814.
PMID
17985626
Source
pubmed
Published In
Medical physics
Volume
34
Issue
10
Publish Date
2007
Start Page
3808
End Page
3814
DOI
10.1118/1.2776669

Accelerating reconstruction of reference digital tomosynthesis using graphics hardware.

The successful implementation of digital tomosynthesis (DTS) for on-board image guided radiation therapy (IGRT) requires fast DTS image reconstruction. Both target and reference DTS image sets are required to support an image registration application for IGRT. Target images are usually DTS image sets reconstructed from on-board projections, which can be accomplished quickly using the conventional filtered backprojection algorithm. Reference images are DTS image sets reconstructed from digitally reconstructed radiographs (DRRs) previously generated from conventional planning CT data. Generating a set of DRRs from planning CT is relatively slow using the conventional ray-casting algorithm. In order to facilitate DTS reconstruction within a clinically acceptable period of time, we implemented a high performance DRR reconstruction algorithm on a graphics processing unit of commercial PC graphics hardware. The performance of this new algorithm was evaluated and compared with that which is achieved using the conventional software-based ray-casting algorithm. DTS images were reconstructed from DRRs previously generated by both hardware and software algorithms. On average, the DRR reconstruction efficiency using the hardware method is improved by a factor of 67 over the software method. The image quality of the DRRs was comparable to those generated using the software-based ray-casting algorithm. Accelerated DRR reconstruction significantly reduces the overall time required to produce a set of reference DTS images from planning CT and makes this technique clinically practical for target localization for radiation therapy.

Authors
Yan, H; Ren, L; Godfrey, DJ; Yin, F-F
MLA Citation
Yan, H, Ren, L, Godfrey, DJ, and Yin, F-F. "Accelerating reconstruction of reference digital tomosynthesis using graphics hardware." Med Phys 34.10 (October 2007): 3768-3776.
PMID
17985622
Source
pubmed
Published In
Medical physics
Volume
34
Issue
10
Publish Date
2007
Start Page
3768
End Page
3776
DOI
10.1118/1.2779945

The management of imaging dose during image-guided radiotherapy: report of the AAPM Task Group 75.

Radiographic image guidance has emerged as the new paradigm for patient positioning, target localization, and external beam alignment in radiotherapy. Although widely varied in modality and method, all radiographic guidance techniques have one thing in common--they can give a significant radiation dose to the patient. As with all medical uses of ionizing radiation, the general view is that this exposure should be carefully managed. The philosophy for dose management adopted by the diagnostic imaging community is summarized by the acronym ALARA, i.e., as low as reasonably achievable. But unlike the general situation with diagnostic imaging and image-guided surgery, image-guided radiotherapy (IGRT) adds the imaging dose to an already high level of therapeutic radiation. There is furthermore an interplay between increased imaging and improved therapeutic dose conformity that suggests the possibility of optimizing rather than simply minimizing the imaging dose. For this reason, the management of imaging dose during radiotherapy is a different problem than its management during routine diagnostic or image-guided surgical procedures. The imaging dose received as part of a radiotherapy treatment has long been regarded as negligible and thus has been quantified in a fairly loose manner. On the other hand, radiation oncologists examine the therapy dose distribution in minute detail. The introduction of more intensive imaging procedures for IGRT now obligates the clinician to evaluate therapeutic and imaging doses in a more balanced manner. This task group is charged with addressing the issue of radiation dose delivered via image guidance techniques during radiotherapy. The group has developed this charge into three objectives: (1) Compile an overview of image-guidance techniques and their associated radiation dose levels, to provide the clinician using a particular set of image guidance techniques with enough data to estimate the total diagnostic dose for a specific treatment scenario, (2) identify ways to reduce the total imaging dose without sacrificing essential imaging information, and (3) recommend optimization strategies to trade off imaging dose with improvements in therapeutic dose delivery. The end goal is to enable the design of image guidance regimens that are as effective and efficient as possible.

Authors
Murphy, MJ; Balter, J; Balter, S; BenComo, JA; Das, IJ; Jiang, SB; Ma, CM; Olivera, GH; Rodebaugh, RF; Ruchala, KJ; Shirato, H; Yin, F-F
MLA Citation
Murphy, MJ, Balter, J, Balter, S, BenComo, JA, Das, IJ, Jiang, SB, Ma, CM, Olivera, GH, Rodebaugh, RF, Ruchala, KJ, Shirato, H, and Yin, F-F. "The management of imaging dose during image-guided radiotherapy: report of the AAPM Task Group 75." Med Phys 34.10 (October 2007): 4041-4063.
PMID
17985650
Source
pubmed
Published In
Medical physics
Volume
34
Issue
10
Publish Date
2007
Start Page
4041
End Page
4063
DOI
10.1118/1.2775667

Minimizing image noise in on-board CT reconstruction using both kilovoltage and megavoltage beam projections.

We studied a recently proposed aggregated CT reconstruction technique which combines the complementary advantages of kilovoltage (kV) and megavoltage (MV) x-ray imaging. Various phantoms were imaged to study the effects of beam orientations and geometry of the imaging object on image quality of reconstructed CT. It was shown that the quality of aggregated CT was correlated with both kV and MV beam orientations and the degree of this correlation depended upon the geometry of the imaging object. The results indicated that the optimal orientations were those when kV beams pass through the thinner portion and MV beams pass through the thicker portion of the imaging object. A special preprocessing procedure was also developed to perform contrast conversions between kV and MV information prior to image reconstruction. The performance of two reconstruction methods, one filtered backprojection method and one iterative method, were compared. The effects of projection number, beam truncation, and contrast conversion on the CT image quality were investigated.

Authors
Zhang, J; Yin, F-F
MLA Citation
Zhang, J, and Yin, F-F. "Minimizing image noise in on-board CT reconstruction using both kilovoltage and megavoltage beam projections." Med Phys 34.9 (September 2007): 3665-3673.
PMID
17926970
Source
pubmed
Published In
Medical physics
Volume
34
Issue
9
Publish Date
2007
Start Page
3665
End Page
3673
DOI
10.1118/1.2768862

A neural network model to predict lung radiation-induced pneumonitis.

A feed-forward neural network was investigated to predict the occurrence of lung radiation-induced Grade 2+ pneumonitis. The database consisted of 235 patients with lung cancer treated using radiotherapy, of whom 34 were diagnosed with Grade 2+ pneumonitis at follow-up. The network was constructed using an algorithm that alternately grew and pruned it, starting from the smallest possible network, until a satisfactory solution was found. The weights and biases of the network were computed using the error back-propagation approach. Momentum and variable leaning techniques were used to speed convergence. Using the growing/pruning approach, the network selected features from 66 dose and 27 non-dose variables. During network training, the 235 patients were randomly split into ten groups of approximately equal size. Eight groups were used to train the network, one group was used for early stopping training to prevent overfitting, and the remaining group was used as a test to measure the generalization capability of the network (cross-validation). Using this methodology, each of the ten groups was considered, in turn, as the test group (ten-fold cross-validation). For the optimized network constructed with input features selected from dose and non-dose variables, the area under the receiver operating characteristics (ROC) curve for cross-validated testing was 0.76 (sensitivity: 0.68, specificity: 0.69). For the optimized network constructed with input features selected only from dose variables, the area under the ROC curve for cross-validation was 0.67 (sensitivity: 0.53, specificity: 0.69). The difference between these two areas was statistically significant (p = 0.020), indicating that the addition of non-dose features can significantly improve the generalization capability of the network. A network for prospective testing was constructed with input features selected from dose and non-dose variables (all data were used for training). The optimized network architecture consisted of six input nodes (features), four hidden nodes, and one output node. The six input features were: lung volume receiving > 16 Gy (V16), generalized equivalent uniform dose (gEUD) for the exponent a = 1 (mean lung dose), gEUD for the exponent a = 3.5, free expiratory volume in 1 s (FEV1), diffusion capacity of carbon monoxide (DLCO%), and whether or not the patient underwent chemotherapy prior to radiotherapy. The significance of each input feature was individually evaluated by omitting it during network training and gauging its impact by the consequent deterioration in cross-validated ROC area. With the exception of FEV1 and whether or not the patient underwent chemotherapy prior to radiotherapy, all input features were found to be individually significant (p < 0.05). The network for prospective testing is publicly available via internet access.

Authors
Chen, S; Zhou, S; Zhang, J; Yin, F-F; Marks, LB; Das, SK
MLA Citation
Chen, S, Zhou, S, Zhang, J, Yin, F-F, Marks, LB, and Das, SK. "A neural network model to predict lung radiation-induced pneumonitis." Med Phys 34.9 (September 2007): 3420-3427.
PMID
17926943
Source
pubmed
Published In
Medical physics
Volume
34
Issue
9
Publish Date
2007
Start Page
3420
End Page
3427
DOI
10.1118/1.2759601

Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS).

Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-angle scan, with typical scan angles ranging from 10 degrees to 40 degrees and acquisition times of less than 10 s. The resulting DTS slices show soft tissue contrast approaching that of full cone-beam CT. External beam radiotherapy target localization using DTS requires the registration of on-board DTS images with corresponding reference image data. This study evaluates three types of reference volume: original reference CT, exact reference DTS (RDTS), and a more computationally efficient approximate reference DTS (RDTSapprox), as well as three different DTS scan angles (22 degrees, 44 degrees, and 65 degrees) for the DTS target localization task. Three-dimensional mutual information (MI) shared between reference and onboard DTS volumes was computed in a region surrounding the spine of a chest phantom, as translations spanning +/-5 mm and rotations spanning +/-5 degrees were simulated along each dimension in the reference volumes. The locations of the MI maxima were used as surrogates for registration accuracy, and the width of the MI peaks were used to characterize the registration robustness. The results show that conventional treatment planning CT volumes are inadequate reference volumes for direct registration with on-board DTS data. The efficient RDTSapprox method also appears insufficient for MI-based registration without further refinement of the technique, though it may be suitable for manual registration performed by a human observer. The exact RDTS volumes, on the other hand, delivered a 3D DTS localization accuracy of 0.5 mm and 0.50 along each axis, using only a single 44 degrees coronal on-board DTS scan of the chest phantom.

Authors
Godfrey, DJ; Ren, L; Yan, H; Wu, Q; Yoo, S; Oldham, M; Yin, FF
MLA Citation
Godfrey, DJ, Ren, L, Yan, H, Wu, Q, Yoo, S, Oldham, M, and Yin, FF. "Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS)." Med Phys 34.8 (August 2007): 3374-3384.
PMID
17879800
Source
pubmed
Published In
Medical physics
Volume
34
Issue
8
Publish Date
2007
Start Page
3374
End Page
3384
DOI
10.1118/1.2756941

Comparison of similarity measures for rigid-body CT/Dual X-ray image registrations.

A set of experiments were conducted to evaluate six similarity measures for intensity-based rigid-body 3D/2D image registration. Similarity measure is an index that measures the similarity between a digitally reconstructed radiograph (DRR) and an x-ray planar image. The registration is accomplished by maximizing the sum of the similarity measures between biplane x-ray images and the corresponding DRRs in an iterative fashion. We have evaluated the accuracy and attraction ranges of the registrations using six different similarity measures on phantom experiments for head, thorax, and pelvis. The images were acquired using Varian Medial System On-Board Imager. Our results indicated that normalized cross correlation and entropy of difference showed a wide attraction range (62 deg and 83 mm mean attraction range, omega(mean)), but the worst accuracy (4.2 mm maximum error, e(max)). The gradient-based similarity measures, gradient correlation and gradient difference, and the pattern intensity showed sub-millimeter accuracy, but narrow attraction ranges (omega(mean)=29 deg, 31 mm). Mutual information was in-between of these two groups (e(max)=2.5 mm, omega(mean)= 48 deg, 52 mm). On the data of 120 x-ray pairs from eight IRB approved prostate patients, the gradient difference showed the best accuracy. In the clinical applications, registrations starting with the mutual information followed by the gradient difference may provide the best accuracy and the most robustness.

Authors
Kim, J; Li, S; Pradhan, D; Hammoud, R; Chen, Q; Yin, F-F; Zhao, Y; Kim, JH; Movsas, B
MLA Citation
Kim, J, Li, S, Pradhan, D, Hammoud, R, Chen, Q, Yin, F-F, Zhao, Y, Kim, JH, and Movsas, B. "Comparison of similarity measures for rigid-body CT/Dual X-ray image registrations." Technol Cancer Res Treat 6.4 (August 2007): 337-346.
PMID
17668942
Source
pubmed
Published In
Technology in cancer research & treatment
Volume
6
Issue
4
Publish Date
2007
Start Page
337
End Page
346
DOI
10.1177/153303460700600411

Predicting lung radiotherapy-induced pneumonitis using a model combining parametric Lyman probit with nonparametric decision trees.

PURPOSE: To develop and test a model to predict for lung radiation-induced Grade 2+ pneumonitis. METHODS AND MATERIALS: The model was built from a database of 234 lung cancer patients treated with radiotherapy (RT), of whom 43 were diagnosed with pneumonitis. The model augmented the predictive capability of the parametric dose-based Lyman normal tissue complication probability (LNTCP) metric by combining it with weighted nonparametric decision trees that use dose and nondose inputs. The decision trees were sequentially added to the model using a "boosting" process that enhances the accuracy of prediction. The model's predictive capability was estimated by 10-fold cross-validation. To facilitate dissemination, the cross-validation result was used to extract a simplified approximation to the complicated model architecture created by boosting. Application of the simplified model is demonstrated in two example cases. RESULTS: The area under the model receiver operating characteristics curve for cross-validation was 0.72, a significant improvement over the LNTCP area of 0.63 (p = 0.005). The simplified model used the following variables to output a measure of injury: LNTCP, gender, histologic type, chemotherapy schedule, and treatment schedule. For a given patient RT plan, injury prediction was highest for the combination of pre-RT chemotherapy, once-daily treatment, female gender and lowest for the combination of no pre-RT chemotherapy and nonsquamous cell histologic type. Application of the simplified model to the example cases revealed that injury prediction for a given treatment plan can range from very low to very high, depending on the settings of the nondose variables. CONCLUSIONS: Radiation pneumonitis prediction was significantly enhanced by decision trees that added the influence of nondose factors to the LNTCP formulation.

Authors
Das, SK; Zhou, S; Zhang, J; Yin, F-F; Dewhirst, MW; Marks, LB
MLA Citation
Das, SK, Zhou, S, Zhang, J, Yin, F-F, Dewhirst, MW, and Marks, LB. "Predicting lung radiotherapy-induced pneumonitis using a model combining parametric Lyman probit with nonparametric decision trees." Int J Radiat Oncol Biol Phys 68.4 (July 15, 2007): 1212-1221.
PMID
17637394
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
68
Issue
4
Publish Date
2007
Start Page
1212
End Page
1221
DOI
10.1016/j.ijrobp.2007.03.064

Self-consistent tumor control probability and normal tissue complication probability models based on generalized EUDa).

Traditional methods to compute the tumor control probability (TCP) or normal tissue complication probability (NTCP) typically require a heterogeneous radiation dose distribution to be converted into a simple uniform dose distribution with an equivalent biological effect. Several power-law type dose-volume-histogram reduction schemes, particularly Niemierko's generalized equivalent uniform dose model [Med. Phys. 26, 1000 (1999)], have been proposed to achieve this goal. In this study, we carefully examine the mathematical outcome of these schemes. We demonstrate that (1) for tumors, with each tumor cell independently responding to local radiation dose, a closed-form analytical solution for tumor survival fraction and TCP can be obtained; (2) for serial structured normal tissues, an exponential power-law form relating survival to functional sub-unit (FSU) radiation is required, and a closed-form analytical solution for the related NTCP is provided; (3) in the case of a parallel structured normal tissue, when NTCP is determined solely by the number of the surviving FSUs, a mathematical solution is available only when there is a non-zero threshold dose and/or a finite critical dose defining the radiotherapy response. Some discussion is offered for the partial irradiation effect on normal tissues in this category; (4) for normal tissues with alternative architectures, where the radiation response of FSU is inhomogeneous, there is no exact global mathematical solution for SF or NTCP within the available schemes. Finally, numerical fits of our models to some experimental data are also presented.

Authors
Zhou, S-M; Das, SK; Wang, Z; Sun, X; Dewhirst, M; Yin, F-F; Marks, LB
MLA Citation
Zhou, S-M, Das, SK, Wang, Z, Sun, X, Dewhirst, M, Yin, F-F, and Marks, LB. "Self-consistent tumor control probability and normal tissue complication probability models based on generalized EUDa)." Medical physics 34.7 (July 2007): 2807-2815.
PMID
28523806
Source
epmc
Published In
Medical physics
Volume
34
Issue
7
Publish Date
2007
Start Page
2807
End Page
2815
DOI
10.1118/1.2740010

Self-consistent tumor control probability and normal tissue complication probability models based on generalized EUD.

Traditional methods to compute the tumor control probability (TCP) or normal tissue complication probability (NTCP) typically require a heterogeneous radiation dose distribution to be converted into a simple uniform dose distribution with an equivalent biological effect. Several power-law type dose-volume-histogram reduction schemes, particularly Niemierko's generalized equivalent uniform dose model [Med. Phys. 26, 1000 (1999)], have been proposed to achieve this goal. In this study, we carefully examine the mathematical outcome of these schemes. We demonstrate that (1) for tumors, with each tumor cell independently responding to local radiation dose, a closed-form analytical solution for tumor survival fraction and TCP can be obtained; (2) for serial structured normal tissues, an exponential power-law form relating survival to functional sub-unit (FSU) radiation is required, and a closed-form analytical solution for the related NTCP is provided; (3) in the case of a parallel structured normal tissue, when NTCP is determined solely by the number of the surviving FSUs, a mathematical solution is available only when there is a non-zero threshold dose and/or a finite critical dose defining the radiotherapy response. Some discussion is offered for the partial irradiation effect on normal tissues in this category; (4) for normal tissues with alternative architectures, where the radiation response of FSU is inhomogeneous, there is no exact global mathematical solution for SF or NTCP within the available schemes. Finally, numerical fits of our models to some experimental data are also presented.

Authors
Zhou, S-M; Das, SK; Wang, Z; Sun, X; Dewhirst, M; Yin, F-F; Marks, LB
MLA Citation
Zhou, S-M, Das, SK, Wang, Z, Sun, X, Dewhirst, M, Yin, F-F, and Marks, LB. "Self-consistent tumor control probability and normal tissue complication probability models based on generalized EUD." Med Phys 34.7 (July 2007): 2807-2815.
PMID
17821988
Source
pubmed
Published In
Medical physics
Volume
34
Issue
7
Publish Date
2007
Start Page
2807
End Page
2815
DOI
10.1118/1.2740010

SU-FF-T-148: Developing a Convenient and Effective IMRT QA Procedure Using MLC Dynalog Files

Authors
Luo, W; Ma, C; Yin, F; Fan, J
MLA Citation
Luo, W, Ma, C, Yin, F, and Fan, J. "SU-FF-T-148: Developing a Convenient and Effective IMRT QA Procedure Using MLC Dynalog Files." June 2007.
Source
crossref
Published In
Medical physics
Volume
34
Issue
6Part9
Publish Date
2007
Start Page
2435
End Page
2435
DOI
10.1118/1.2760807

SU-FF-T-246: Implementation of Helical CT Source in DOSXYZnrc/EGSnrc Monte Carlo Code

Authors
Kim, S; Yoshizumi, T; Yin, F
MLA Citation
Kim, S, Yoshizumi, T, and Yin, F. "SU-FF-T-246: Implementation of Helical CT Source in DOSXYZnrc/EGSnrc Monte Carlo Code." June 2007.
Source
crossref
Published In
Medical physics
Volume
34
Issue
6Part11
Publish Date
2007
Start Page
2458
End Page
2458
DOI
10.1118/1.2760907

TH-D-M100E-07: Determining the Geometric and Dosimetric Accuracy of MRI Based IMRT Treatment Plan for Patients with Prostate, Brain, and Head and Neck Cancers

Authors
Ahmed, S; Das, S; Yin, F
MLA Citation
Ahmed, S, Das, S, and Yin, F. "TH-D-M100E-07: Determining the Geometric and Dosimetric Accuracy of MRI Based IMRT Treatment Plan for Patients with Prostate, Brain, and Head and Neck Cancers." Medical Physics 34.6Part24 (June 2007): 2644-2644.
Source
crossref
Published In
Medical physics
Volume
34
Issue
6Part24
Publish Date
2007
Start Page
2644
End Page
2644
DOI
10.1118/1.2761734

MO-D-M100F-01: Emerging Techniques Using Digital Tomosynthesis

Authors
Yin, F
MLA Citation
Yin, F. "MO-D-M100F-01: Emerging Techniques Using Digital Tomosynthesis." Medical Physics 34.6Part15 (June 2007): 2518-2518.
Source
crossref
Published In
Medical physics
Volume
34
Issue
6Part15
Publish Date
2007
Start Page
2518
End Page
2518
DOI
10.1118/1.2761225

A model for optimizing adenoviral delivery in human cancer gene therapy trials.

Optimization of adenoviral delivery to the target volume is required for adenovirus-mediated cancer gene therapy to reach its maximal potential. The purpose of these studies was to develop a model of gene expression to improve adenovirus-mediated cancer gene therapy in the clinic. We measured the distribution of gene expression after a single deposit of a replication-competent adenovirus carrying the human sodium iodide symporter (hNIS) reporter gene was delivered to naive canine prostate and to human tumor xenografts. We generated hypothetical treatment plans for two prospective prostate cancer patients, using standard brachytherapy algorithms. In both models, the gene expression distribution from a single adenoviral deposit could be accurately described by a Gaussian function. In the naive canine prostate, a 0.1-ml deposit of 3 x 10(11) viral particles (VP) resulted in a gene expression volume of 1.14 +/- 0.70 cm(3), indicating that a minimum of 40 adenoviral deposits would be required to cover a 40-cm(3) prostate with therapeutic gene expression. On a viral particle basis, the gene expression volume obtained in human tumor xenografts (7 x 10(-12) cm(3)/VP) was twice that (3.5 x 10(-12) cm(3)/VP) measured in the naive canine prostate. Hypothetical treatment plans for two prostates indicated that 26 and 57 0.1-ml adenoviral deposits would be required to cover, respectively, 24- and 49-cm(3) prostates with gene expression. Although our studies focused on prostate, we believe the methodology to model gene expression presented here has much broader application to optimize treatment plans in other solid tumor sites; this assertion should be confirmed experimentally.

Authors
Barton, KN; Freytag, SO; Nurushev, T; Yoo, S; Lu, M; Yin, F-F; Li, S; Movsas, B; Kim, JH; Brown, SL
MLA Citation
Barton, KN, Freytag, SO, Nurushev, T, Yoo, S, Lu, M, Yin, F-F, Li, S, Movsas, B, Kim, JH, and Brown, SL. "A model for optimizing adenoviral delivery in human cancer gene therapy trials." Hum Gene Ther 18.6 (June 2007): 562-572.
PMID
17594241
Source
pubmed
Published In
Human Gene Therapy
Volume
18
Issue
6
Publish Date
2007
Start Page
562
End Page
572
DOI
10.1089/hum.2007.004

Predicting late skin effects using digital infrared imaging for breast cancer patients treated with radiation

Authors
Mbibi, O; Craciunescu, O; Fatunase, T; Marks, L; Yin, F
MLA Citation
Mbibi, O, Craciunescu, O, Fatunase, T, Marks, L, and Yin, F. "Predicting late skin effects using digital infrared imaging for breast cancer patients treated with radiation." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2392
End Page
2392
DOI
10.1118/1.2760610

Clinical evaluation using digital tomosynthesis for positioning verification of breath-hold liver treatment

Authors
Fuller, J; Wu, Q; Godfrey, D; Zhang, I; Wang, Z; Yoo, S; Yin, F
MLA Citation
Fuller, J, Wu, Q, Godfrey, D, Zhang, I, Wang, Z, Yoo, S, and Yin, F. "Clinical evaluation using digital tomosynthesis for positioning verification of breath-hold liver treatment." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2381
End Page
2381
DOI
10.1118/1.2760563

Three-dimensional MRI and cone-beam CT matching for localization of prostate cancer treatment

Authors
Wang, Z; Wu, QJ; Lee, WR; Yin, F
MLA Citation
Wang, Z, Wu, QJ, Lee, WR, and Yin, F. "Three-dimensional MRI and cone-beam CT matching for localization of prostate cancer treatment." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2379
End Page
2379
DOI
10.1118/1.2760553

Improvement of localization accuracy by using 3D cone beam CT for stereotactic body radiation therapy of liver, lung and spine lesions

Authors
Wang, Z; Nelson, J; Yoo, S; Wu, QJ; Kirkpatrick, J; Larrier, N; Meyer, J; Willett, C; Yin, F
MLA Citation
Wang, Z, Nelson, J, Yoo, S, Wu, QJ, Kirkpatrick, J, Larrier, N, Meyer, J, Willett, C, and Yin, F. "Improvement of localization accuracy by using 3D cone beam CT for stereotactic body radiation therapy of liver, lung and spine lesions." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2459
End Page
2459
DOI
10.1118/1.2760913

Development of clinical application platform using digital tomosynthesis for target localization

Authors
Yan, H; Ren, L; Godfrey, D; Yin, F
MLA Citation
Yan, H, Ren, L, Godfrey, D, and Yin, F. "Development of clinical application platform using digital tomosynthesis for target localization." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2346
End Page
2347
DOI
10.1118/1.2760416

Dosimetric comparison of MapCheck with Monte Carlo simulations

Authors
Luo, W; Yin, F; Ma, C; Fan, J; Song, H
MLA Citation
Luo, W, Yin, F, Ma, C, Fan, J, and Song, H. "Dosimetric comparison of MapCheck with Monte Carlo simulations." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2440
End Page
2440
DOI
10.1118/1.2760831

On the use of ice as a water-equivalent solid medium for brachytherapy dosimetry measurement

Authors
Song, H; Chen, Z; Yue, N; Wu, QJ; Yin, F
MLA Citation
Song, H, Chen, Z, Yue, N, Wu, QJ, and Yin, F. "On the use of ice as a water-equivalent solid medium for brachytherapy dosimetry measurement." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2476
End Page
2476
DOI
10.1118/1.2760989

A high MU efficiency dynamic MLC leaf sequencing algorithm

Authors
Thongphiew, D; Wu, Q; Chankong, V; Song, H; Yin, F
MLA Citation
Thongphiew, D, Wu, Q, Chankong, V, Song, H, and Yin, F. "A high MU efficiency dynamic MLC leaf sequencing algorithm." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2404
End Page
2404
DOI
10.1118/1.2760659

Real-time lung tumor motion prediction using neural network based models constructed from unsorted cine CT images

Authors
Maurer, J; Yan, H; Wang, Z; Yin, F
MLA Citation
Maurer, J, Yan, H, Wang, Z, and Yin, F. "Real-time lung tumor motion prediction using neural network based models constructed from unsorted cine CT images." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2573
End Page
2573
DOI
10.1118/1.2761447

The impact of SBRT treatment techniques on dose delivery in presence of organ motion and deformation

Authors
Wu, Q; Thongphiew, D; Wang, Z; Yin, F
MLA Citation
Wu, Q, Thongphiew, D, Wang, Z, and Yin, F. "The impact of SBRT treatment techniques on dose delivery in presence of organ motion and deformation." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2642
End Page
2642
DOI
10.1118/1.2761726

Amplitude gated breath-hold treatment for upper abdominal lesions with on board imaging guidance

Authors
Wang, Z; Yin, F; Czito, B; Wu, QJ; Zhou, S; Willett, C
MLA Citation
Wang, Z, Yin, F, Czito, B, Wu, QJ, Zhou, S, and Willett, C. "Amplitude gated breath-hold treatment for upper abdominal lesions with on board imaging guidance." June 2007.
Source
wos-lite
Published In
Medical physics
Volume
34
Issue
6
Publish Date
2007
Start Page
2649
End Page
2649
DOI
10.1118/1.2761753

On-line re-optimization of prostate IMR