You are here

Cai, Jing

Overview:

Image-guided Radiation Therapy (IGRT), Magnetic Resonance Imaging (MRI), Tumor Motion Management, Four-Dimensional Radiation Therapy (4DRT), Stereotatic-Body Radiation Therapy (SBRT), Brachytherapy, Treatment Planning, Lung Cancer, Liver Cancer, Cervical Cancer.



Positions:

Associate Professor of Radiation Oncology

Radiation Oncology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 2006

Ph.D. — University of Virginia

Grants:

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

Administered By
Radiation Oncology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 07, 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
Principal Investigator
Start Date
January 11, 2013
End Date
December 31, 2016

Cross-disciplinary Training in Medical Physics

Administered By
Radiology
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 01, 2007
End Date
June 30, 2013

Publications:

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

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

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 (December 2016).
Source
crossref
Published In
Advances in Radiation Oncology
Publish Date
2016
DOI
10.1016/j.adro.2016.12.002

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

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

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

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

Methods, safety, and early clinical outcomes of dose escalation using simultaneous integrated and sequential boosts in patients with locally advanced gynecologic malignancies.

OBJECTIVE: To evaluate the safety of dose escalated radiotherapy using a simultaneous integrated boost technique in patients with locally advanced gynecological malignancies. METHODS: Thirty-nine women with locally advanced gynecological malignancies were treated with intensity modulated radiation therapy utilizing a simultaneous integrated boost (SIB) technique for gross disease in the para-aortic and/or pelvic nodal basins, sidewall extension, or residual primary disease. Women were treated to 45Gy in 1.8Gy fractions to elective nodal regions. Gross disease was simultaneously treated to 55Gy in 2.2Gy fractions (n=44 sites). An additional sequential boost of 10Gy in 2Gy fractions was delivered if deemed appropriate (n=29 sites). Acute and late toxicity, local control in the treated volumes (LC), overall survival (OS), and distant metastases (DM) were assessed. RESULTS: All were treated with a SIB to a dose of 55Gy. Twenty-four patients were subsequently treated with a sequential boost to a median dose of 65Gy. Median follow-up was 18months. Rates of acute>grade 2 gastrointestinal (GI), genitourinary (GU), and hematologic (heme) toxicities were 2.5%, 0%, and 30%, respectively. There were no grade 4 acute toxicities. At one year, grade 1-2 late GI toxicities were 24.5%. There were no grade 3 or 4 late GI toxicities. Rates of grade 1-2 late GU toxicities were 12.7%. There were no grade 3 or 4 late GU toxicities. CONCLUSION: Dose escalated radiotherapy using a SIB results in acceptable rates of acute toxicity.

Authors
Boyle, J; Craciunescu, O; Steffey, B; Cai, J; Chino, J
MLA Citation
Boyle, J, Craciunescu, O, Steffey, B, Cai, J, and Chino, J. "Methods, safety, and early clinical outcomes of dose escalation using simultaneous integrated and sequential boosts in patients with locally advanced gynecologic malignancies." Gynecologic oncology 135.2 (November 2014): 239-243.
PMID
25192879
Source
epmc
Published In
Gynecologic Oncology
Volume
135
Issue
2
Publish Date
2014
Start Page
239
End Page
243
DOI
10.1016/j.ygyno.2014.08.037

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

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

Body mass index, dose to organs at risk during vaginal brachytherapy, and the role of three-dimensional CT-based treatment planning.

To assess the effect of body mass index (BMI) on dose to organs at risk (OARs) during high-dose-rate vaginal brachytherapy and evaluate the role of three-dimensional dose evaluation during treatment planning.Three-dimensional dosimetric data for rectum, bladder, sigmoid colon, and small bowel for 125 high-dose-rate vaginal brachytherapy fractions were analyzed. Dose-volume histograms were generated for D0.1 cc and D2 cc of each OAR. Contributing factors including the use of urinary catheter and cylinder size were also recorded. As different dose fractionations were used, the OAR doses were tabulated as a percent dose prescribed to 0.5cm. All patients were treated to 4cm of the vaginal length.Median BMI in this cohort was 31.7kg/m(2). The BMI values had a weak inverse correlation with D0.1 cc to sigmoid colon (rs=-0.18, p=0.047) and D0.1 cc to bladder (rs=-0.19, p=0.038). There was a strong inverse correlation of D2 cc and increasing BMI (rs=-0.64, p=0.003). The median D2 cc was 25.1% for BMI higher than 31 and 61.9% for BMI of 31 or lower. For D0.1 cc, there was also a strong inverse correlation with increasing BMI (rs=-0.57, p<0.001). Median D1 cc was 33.5% for BMI >31 and 84.4% for BMI ≤ 31. On multivariate analysis higher BMI remained a significant predictor of lower small bowel D2 cc (p<0.001) and D0.1 cc (p<0.001).Women with a lower BMI receive higher doses to the bladder and small bowel compared with those with a higher BMI. Three-dimensional dose evaluation should be considered in patients with low BMI, particularly when combined with external beam radiation.

Authors
Boyle, JM; Craciunescu, O; Steffey, B; Cai, J; Chino, J
MLA Citation
Boyle, JM, Craciunescu, O, Steffey, B, Cai, J, and Chino, J. "Body mass index, dose to organs at risk during vaginal brachytherapy, and the role of three-dimensional CT-based treatment planning." Brachytherapy 13.4 (July 2014): 332-336.
PMID
24439964
Source
epmc
Published In
Brachytherapy
Volume
13
Issue
4
Publish Date
2014
Start Page
332
End Page
336
DOI
10.1016/j.brachy.2013.12.002

Uveal melanoma treated with iodine-125 episcleral plaque: An analysis of dose on disease control and visual outcomes

Purpose To investigate, in the treatment of uveal melanomas, how tumor control, radiation toxicity, and visual outcomes are affected by the radiation dose at the tumor apex. Methods and Materials A retrospective review was performed to evaluate patients treated for uveal melanoma with 125I plaques between 1988 and 2010. Radiation dose is reported as dose to tumor apex and dose to 5 mm. Primary endpoints included time to local failure, distant failure, and death. Secondary endpoints included eye preservation, visual acuity, and radiation-related complications. Univariate and multivariate analyses were performed to determine associations between radiation dose and the endpoint variables. Results One hundred ninety patients with sufficient data to evaluate the endpoints were included. The 5-year local control rate was 91%. The 5-year distant metastases rate was 10%. The 5-year overall survival rate was 84%. There were no differences in outcome (local control, distant metastases, overall survival) when dose was stratified by apex dose quartile (<69 Gy, 69-81 Gy, 81-89 Gy, >89 Gy). However, increasing apex dose and dose to 5-mm depth were correlated with greater visual acuity loss (P=.02, P=.0006), worse final visual acuity (P=.02, P<.0001), and radiation complications (P<.0001, P=.0009). In addition, enucleation rates were worse with increasing quartiles of dose to 5 mm (P=.0001). Conclusions Doses at least as low as 69 Gy prescribed to the tumor apex achieve rates of local control, distant metastasis-free survival, and overall survival that are similar to radiation doses of 85 Gy to the tumor apex, but with improved visual outcomes. © 2014 Elsevier Inc. All rights reserved.

Authors
Perez, BA; Mettu, P; Vajzovic, L; Rivera, D; Alkaissi, A; Steffey, BA; Cai, J; Stinnett, S; Dutton, JJ; Buckley, EG; Halperin, E; Marks, LB; Mruthyunjaya, P; Kirsch, DG
MLA Citation
Perez, BA, Mettu, P, Vajzovic, L, Rivera, D, Alkaissi, A, Steffey, BA, Cai, J, Stinnett, S, Dutton, JJ, Buckley, EG, Halperin, E, Marks, LB, Mruthyunjaya, P, and Kirsch, DG. "Uveal melanoma treated with iodine-125 episcleral plaque: An analysis of dose on disease control and visual outcomes." International Journal of Radiation Oncology Biology Physics 89.1 (May 1, 2014): 127-136.
Source
scopus
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
89
Issue
1
Publish Date
2014
Start Page
127
End Page
136
DOI
10.1016/j.ijrobp.2014.01.026

Uveal melanoma treated with iodine-125 episcleral plaque: an analysis of dose on disease control and visual outcomes.

To investigate, in the treatment of uveal melanomas, how tumor control, radiation toxicity, and visual outcomes are affected by the radiation dose at the tumor apex.A retrospective review was performed to evaluate patients treated for uveal melanoma with (125)I plaques between 1988 and 2010. Radiation dose is reported as dose to tumor apex and dose to 5 mm. Primary endpoints included time to local failure, distant failure, and death. Secondary endpoints included eye preservation, visual acuity, and radiation-related complications. Univariate and multivariate analyses were performed to determine associations between radiation dose and the endpoint variables.One hundred ninety patients with sufficient data to evaluate the endpoints were included. The 5-year local control rate was 91%. The 5-year distant metastases rate was 10%. The 5-year overall survival rate was 84%. There were no differences in outcome (local control, distant metastases, overall survival) when dose was stratified by apex dose quartile (<69 Gy, 69-81 Gy, 81-89 Gy, >89 Gy). However, increasing apex dose and dose to 5-mm depth were correlated with greater visual acuity loss (P=.02, P=.0006), worse final visual acuity (P=.02, P<.0001), and radiation complications (P<.0001, P=.0009). In addition, enucleation rates were worse with increasing quartiles of dose to 5 mm (P=.0001).Doses at least as low as 69 Gy prescribed to the tumor apex achieve rates of local control, distant metastasis-free survival, and overall survival that are similar to radiation doses of 85 Gy to the tumor apex, but with improved visual outcomes.

Authors
Perez, BA; Mettu, P; Vajzovic, L; Rivera, D; Alkaissi, A; Steffey, BA; Cai, J; Stinnett, S; Dutton, JJ; Buckley, EG; Halperin, E; Marks, LB; Mruthyunjaya, P; Kirsch, DG
MLA Citation
Perez, BA, Mettu, P, Vajzovic, L, Rivera, D, Alkaissi, A, Steffey, BA, Cai, J, Stinnett, S, Dutton, JJ, Buckley, EG, Halperin, E, Marks, LB, Mruthyunjaya, P, and Kirsch, DG. "Uveal melanoma treated with iodine-125 episcleral plaque: an analysis of dose on disease control and visual outcomes." International journal of radiation oncology, biology, physics 89.1 (May 2014): 127-136.
PMID
24613808
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
89
Issue
1
Publish Date
2014
Start Page
127
End Page
136
DOI
10.1016/j.ijrobp.2014.01.026

Point/Counterpoint. A 3D-conformal technique is better than IMRT or VMAT for lung SBRT.

Authors
Cai, J; Malhotra, HK; Orton, CG
MLA Citation
Cai, J, Malhotra, HK, and Orton, CG. "Point/Counterpoint. A 3D-conformal technique is better than IMRT or VMAT for lung SBRT." Medical physics 41.4 (April 2014): 040601-.
PMID
24694118
Source
epmc
Published In
Medical physics
Volume
41
Issue
4
Publish Date
2014
Start Page
040601
DOI
10.1118/1.4856175

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

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

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

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. © 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

Body mass index, dose to organs at risk during vaginal brachytherapy, and the role of three-dimensional CT-based treatment planning

Purpose: To assess the effect of body mass index (BMI) on dose to organs at risk (OARs) during high-dose-rate vaginal brachytherapy and evaluate the role of three-dimensional dose evaluation during treatment planning. Methods and Materials: Three-dimensional dosimetric data for rectum, bladder, sigmoid colon, and small bowel for 125 high-dose-rate vaginal brachytherapy fractions were analyzed. Dose-volume histograms were generated for D0.1 cc and D2 cc of each OAR. Contributing factors including the use of urinary catheter and cylinder size were also recorded. As different dose fractionations were used, the OAR doses were tabulated as a percent dose prescribed to 0.5cm. All patients were treated to 4cm of the vaginal length. Results: Median BMI in this cohort was 31.7kg/m2. The BMI values had a weak inverse correlation with D0.1 cc to sigmoid colon (rs=-0.18, p=0.047) and D0.1 cc to bladder (rs=-0.19, p=0.038). There was a strong inverse correlation of D2 cc and increasing BMI (rs=-0.64, p=0.003). The median D2 cc was 25.1% for BMI higher than 31 and 61.9% for BMI of 31 or lower. For D0.1 cc, there was also a strong inverse correlation with increasing BMI (rs=-0.57, p<0.001). Median D1 cc was 33.5% for BMI >31 and 84.4% for BMI ≤ 31. On multivariate analysis higherBMI remained a significant predictor of lower small bowel D2 cc (p<0.001) and D0.1 cc (p<0.001). Conclusions: Women with a lower BMI receive higher doses to the bladder and small bowel compared with those with a higher BMI. Three-dimensional dose evaluation should be considered in patients with low BMI, particularly when combined with external beam radiation. © 2014 American Brachytherapy Society.

Authors
Boyle, JM; Craciunescu, O; Steffey, B; Cai, J; Chino, J
MLA Citation
Boyle, JM, Craciunescu, O, Steffey, B, Cai, J, and Chino, J. "Body mass index, dose to organs at risk during vaginal brachytherapy, and the role of three-dimensional CT-based treatment planning." Brachytherapy 13.4 (January 1, 2014): 332-336.
Source
scopus
Published In
Brachytherapy
Volume
13
Issue
4
Publish Date
2014
Start Page
332
End Page
336
DOI
10.1016/j.brachy.2013.12.002

An adaptive finite element method to cope with a large scale lung deformation in magnetic resonance images

© 2014 IEEE.The purpose of this study is to present an adaptive deformable image registration method to improve the performance of a multi-resolution "demons" registration algorithm in handling large scale lung deformation observed in 4D-MR images. Specifically, a finite element method (FEM) was integrated with MR tagging information to correct registration errors in the lung region. The displacements of 349 tagged grids were calculated with an average of 3.5 cm. The mean error of the demons registration over the tags was 2.5 cm which was reduced to 0.7 cm by the FEM registration. The FEM-generated transformation was merged to the demons deformation map without introducing any discontinuity. This method can help correct deformable registration errors identified in the clinical setting.

Authors
Zhong, H; Cai, J; Glide-Hurst, C; Chetty, IJ
MLA Citation
Zhong, H, Cai, J, Glide-Hurst, C, and Chetty, IJ. "An adaptive finite element method to cope with a large scale lung deformation in magnetic resonance images." January 1, 2014.
Source
scopus
Published In
2014 IEEE 11th International Symposium on Biomedical Imaging, ISBI 2014
Publish Date
2014
Start Page
770
End Page
773

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

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 (DA) between the SBV-derived breathing signal and the RPM signal were calculated. 4D CT reconstructedbased on the SBV surrogate (4D CTSBV) were compared to those clinically generated based on RPM (4D CTRPM). Image quality of the 4D CT were scored (SSBV and SRPM, 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 boxposition (P), breathing period (T), amplitude (A), period variability (VT), amplitude variability (VA), and space-dependent phase shift (F) were determined and correlated to SSBV. The phantom study showed excellent match between the SBV-derivedbreathing signal and the RPM signal (R = 0.99, D= -3.0%, DA = 4.5%). In the patient study, the mean (± standard deviation (SD)) R, D, DA, T, VT, A, VA, 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 DA (p = 0.04 and 0.001, respectively) were found between the lung cancer patients and the abdominal cancer patients. 4D CTRPM slightly outperformed 4DCTSBV: the mean (±SD) SRPM and SSBV 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 cancerpatients. The difference between SRPM and SSBV was insignificant for the abdominal patients (p = 0.59). F correlated moderately with SSBV (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; Jennifer, O; Yoo, S; Hong, G; Kelsey, C; Yin, FF
MLA Citation
Cai, J, Chang, Z, Jennifer, O, Yoo, S, Hong, G, Kelsey, C, and Yin, FF. "Investigation of sliced body volume (SBV) as respiratory surrogate." Journal of Applied Clinical Medical Physics 14.1 (February 14, 2013): 71-80.
Source
scopus
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

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

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

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, FF
MLA Citation
Ge, H, Cai, J, Kelsey, CR, and Yin, FF. "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

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

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

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

Feasibility of MR-alone-based Brachytherapy Treatment Planning Using a Titanium Tandem and Ring Applicator for Cervical Cancer

Authors
Cai, J; Chino, J; Qin, Y; De Oliveira, TR; Adamson, J; Steffey, B; Craciunescu, O
MLA Citation
Cai, J, Chino, J, Qin, Y, De Oliveira, TR, Adamson, J, Steffey, B, and Craciunescu, O. "Feasibility of MR-alone-based Brachytherapy Treatment Planning Using a Titanium Tandem and Ring Applicator for Cervical Cancer." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S803
End Page
S803

Multicatheter Vaginal Balloon Brachytherapy: One Year's Clinical Experience

Authors
Chino, JP; Steffey, B; Cai, J; Adamson, J; Craciunescu, O
MLA Citation
Chino, JP, Steffey, B, Cai, J, Adamson, J, and Craciunescu, O. "Multicatheter Vaginal Balloon Brachytherapy: One Year's Clinical Experience." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S460
End Page
S460

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

Urinary Catheterization Increases the Dose to Bowel During Vaginal Brachytherapy

Authors
Zhu, L; Craciunescu, O; Cai, J; Steffey, B; Adamson, J; Chino, JP
MLA Citation
Zhu, L, Craciunescu, O, Cai, J, Steffey, B, Adamson, J, and Chino, JP. "Urinary Catheterization Increases the Dose to Bowel During Vaginal Brachytherapy." November 1, 2012.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
S455
End Page
S455

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

Commissioning a CT-compatible LDR tandem and ovoid applicator using Monte Carlo calculation and 3D dosimetry.

PURPOSE: To determine the geometric and dose attenuation characteristics of a new commercially available CT-compatible LDR tandem and ovoid (T&O) applicator using Monte Carlo calculation and 3D dosimetry. METHODS: For geometric characterization, we quantified physical dimensions and investigated a systematic difference found to exist between nominal ovoid angle and the angle at which the afterloading buckets fall within the ovoid. For dosimetric characterization, we determined source attenuation through asymmetric gold shielding in the buckets using Monte Carlo simulations and 3D dosimetry. Monte Carlo code MCNP5 was used to simulate 1.5 × 10(9) photon histories from a (137)Cs source placed in the bucket to achieve statistical uncertainty of 1% at a 6 cm distance. For 3D dosimetry, the distribution about an unshielded source was first measured to evaluate the system for (137)Cs, after which the distribution was measured about sources placed in each bucket. Cylindrical PRESAGE(®) dosimeters (9.5 cm diameter, 9.2 cm height) with a central channel bored for source placement were supplied by Heuris Inc. The dosimeters were scanned with the Duke Large field of view Optical CT-Scanner before and after delivering a nominal dose at 1 cm of 5-8 Gy. During irradiation the dosimeter was placed in a water phantom to provide backscatter. Optical CT scan time lasted 15 min during which 720 projections were acquired at 0.5° increments, and a 3D distribution was reconstructed with a (0.05 cm)(3) isotropic voxel size. The distributions about the buckets were used to calculate a 3D distribution of transmission rate through the bucket, which was applied to a clinical CT-based T&O implant plan. RESULTS: The systematic difference in bucket angle relative to the nominal ovoid angle (105°) was 3.1°-4.7°. A systematic difference in bucket angle of 1°, 5°, and 10° caused a 1% ± 0.1%, 1.7% ± 0.4%, and 2.6% ± 0.7% increase in rectal dose, respectively, with smaller effect to dose to Point A, bladder, sigmoid, and bowel. For 3D dosimetry, 90.6% of voxels had a 3D γ-index (criteria = 0.1 cm, 3% local signal) below 1.0 when comparing measured and expected dose about the unshielded source. Dose transmission through the gold shielding at a radial distance of 1 cm was 85.9% ± 0.2%, 83.4% ± 0.7%, and 82.5% ± 2.2% for Monte Carlo, and measurement for left and right buckets, respectively. Dose transmission was lowest at oblique angles from the bucket with a minimum of 56.7% ± 0.8%, 65.6% ± 1.7%, and 57.5% ± 1.6%, respectively. For a clinical T&O plan, attenuation from the buckets leads to a decrease in average Point A dose of ∼3.2% and decrease in D(2cc) to bladder, rectum, bowel, and sigmoid of 5%, 18%, 6%, and 12%, respectively. CONCLUSIONS: Differences between dummy and afterloading bucket position in the ovoids is minor compared to effects from asymmetric ovoid shielding, for which rectal dose is most affected. 3D dosimetry can fulfill a novel role in verifying Monte Carlo calculations of complex dose distributions as are common about brachytherapy sources and applicators.

Authors
Adamson, J; Newton, J; Yang, Y; Steffey, B; Cai, J; Adamovics, J; Oldham, M; Chino, J; Craciunescu, O
MLA Citation
Adamson, J, Newton, J, Yang, Y, Steffey, B, Cai, J, Adamovics, J, Oldham, M, Chino, J, and Craciunescu, O. "Commissioning a CT-compatible LDR tandem and ovoid applicator using Monte Carlo calculation and 3D dosimetry." Med Phys 39.7 (July 2012): 4515-4523.
PMID
22830783
Source
pubmed
Published In
Medical physics
Volume
39
Issue
7
Publish Date
2012
Start Page
4515
End Page
4523
DOI
10.1118/1.4730501

A Fourier Technique for Markerless, Self-Sorted 4D-CBCT: Effect of Respiratory Characteristics

Authors
Vergalasova, I; Cai, J; Yin, F
MLA Citation
Vergalasova, I, Cai, J, and Yin, F. "A Fourier Technique for Markerless, Self-Sorted 4D-CBCT: Effect of Respiratory Characteristics." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3902
End Page
3902

Implementing 4D XCAT Phantom for 4D Radiotherapy Research

Authors
Panta, R; Segars, W; Yin, F; Cai, J
MLA Citation
Panta, R, Segars, W, Yin, F, and Cai, J. "Implementing 4D XCAT Phantom for 4D Radiotherapy Research." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3686
End Page
3686

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. "Evaluating Radiation-Induced White Matter Changes in Patients with Recurrent Malignant Gliomas Under Treatment of Stereotactic Radiosurgery Using Diffusion Tensor Imaging." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3937
End Page
3937

Establishing a 4D MRI Program for Imaging Moving Tumors

Authors
Cai, J; Hu, Y; Tryggestad, E; Parikh, P
MLA Citation
Cai, J, Hu, Y, Tryggestad, E, and Parikh, P. "Establishing a 4D MRI Program for Imaging Moving Tumors." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3878
End Page
3879

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

Image Guided Adaptive Brachytherapy for Cervical Cancer

Authors
Craciunescu, O; Cai, J; de Leeuw, A; Kirisits, C
MLA Citation
Craciunescu, O, Cai, J, de Leeuw, A, and Kirisits, C. "Image Guided Adaptive Brachytherapy for Cervical Cancer." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3913
End Page
3913

Commissioning a CT Compatible LDR T&O Applicator Using Analytical Calculation with 1D and 3D Dosimetry

Authors
Adamson, J; Newton, J; Steffey, B; Cai, J; Adamovics, J; Oldham, M; Chino, J; Craciunescu, O
MLA Citation
Adamson, J, Newton, J, Steffey, B, Cai, J, Adamovics, J, Oldham, M, Chino, J, and Craciunescu, O. "Commissioning a CT Compatible LDR T&O Applicator Using Analytical Calculation with 1D and 3D Dosimetry." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3612
End Page
3612

Phase-Matched Digital Tomosynthesis (DTS) Imaging for Simultaneous Target Verification During Volumetric Modulated Arc Therapy (VMAT) Treatment

Authors
Zhang, Y; Ren, L; Vergalasova, I; Cai, J; Yin, F
MLA Citation
Zhang, Y, Ren, L, Vergalasova, I, Cai, J, and Yin, F. "Phase-Matched Digital Tomosynthesis (DTS) Imaging for Simultaneous Target Verification During Volumetric Modulated Arc Therapy (VMAT) Treatment." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3889
End Page
3890

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

4D-MRI Based On Body Area (BA) Surrogate and Sagittal Image Acquisition

Authors
Qin, Y; Chang, Z; Segars, W; Yin, F; Cai, J
MLA Citation
Qin, Y, Chang, Z, Segars, W, Yin, F, and Cai, J. "4D-MRI Based On Body Area (BA) Surrogate and Sagittal Image Acquisition." June 2012.
Source
wos-lite
Published In
Medical physics
Volume
39
Issue
6
Publish Date
2012
Start Page
3622
End Page
3622

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

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

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

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

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

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

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

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

Helical tomotherapy planning for lung cancer based on ventilation magnetic resonance imaging

To investigate the feasibility of lung ventilation-based treatment planning, computed tomography and hyperpolarized (HP) helium-3 (He-3) magnetic resonance imaging (MRI) ventilation images of 6 subjects were coregistered for intensity-modulated radiation therapy planning in Tomotherapy. Highly-functional lungs (HFL) and less-functional lungs (LFL) were contoured based on their ventilation image intensities, and a cylindrical planning-target-volume was simulated at locations adjacent to both HFL and LFL. Annals of an anatomy-based plan (Plan 1) and a ventilation-based plan (Plan 2) were generated. The following dosimetric parameters were determined and compared between the 2 plans: percentage of total/HFL volume receiving ≥20 Gy, 15 Gy, 10 Gy, and 5 Gy (TLV 20, HFLV 20, TLV 15, HFLV 15, TLV 10, HFLV 10, TLV 5, HFLV 5), mean total/HFL dose (MTLD/HFLD), maximum doses to all organs at risk (OARs), and target dose conformality. Compared with Plan 1, Plan 2 reduced mean HFLD (mean reduction, 0.8 Gy), MTLD (mean reduction, 0.6 Gy), HFLV 20 (mean reduction, 1.9%), TLV 20 (mean reduction, 1.5%), TLV 15 (mean reduction, 1.7%), and TLV 10 (mean reduction, 2.1%). P-values of the above comparisons are less than 0.05 using the Wilcoxon signed rank test. For HFLV 15, HFLV 10, TLV 5, and HTLV 5, Plan 2 resulted in lower values than plan 1 but the differences are not significant (P-value range, 0.063-0.219). Plan 2 did not significantly change maximum doses to OARs (P-value range, 0.063-0.563) and target conformality (P = 1.000). HP He-3 MRI of patients with lung disease shows a highly heterogeneous ventilation capacity that can be utilized for functional treatment planning. Moderate but statistically significant improvements in sparing functional lungs were achieved using helical tomotherapy plans. © 2011.

Authors
Cai, J; McLawhorn, R; Altes, TA; Lange, ED; Read, PW; Larner, JM; Benedict, SH; Sheng, K
MLA Citation
Cai, J, McLawhorn, R, Altes, TA, Lange, ED, Read, PW, Larner, JM, Benedict, SH, and Sheng, K. "Helical tomotherapy planning for lung cancer based on ventilation magnetic resonance imaging." Medical Dosimetry 36.4 (2011): 389-396.
PMID
21377866
Source
scival
Published In
Medical Dosimetry
Volume
36
Issue
4
Publish Date
2011
Start Page
389
End Page
396
DOI
10.1016/j.meddos.2010.09.008

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

An Improved Method for Delineating Individualized ITV for SBRT of Lung Cancer

Authors
Ge, H; Cai, J; Kelsey, C; Yin, E
MLA Citation
Ge, H, Cai, J, Kelsey, C, and Yin, E. "An Improved Method for Delineating Individualized ITV for SBRT of Lung Cancer." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S624-S624.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S624
End Page
S624

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

Imaging Tumor Motion using 4D-MRI

Authors
Cai, J; Chang, Z; Yin, F
MLA Citation
Cai, J, Chang, Z, and Yin, F. "Imaging Tumor Motion using 4D-MRI." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S122-S123.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S122
End Page
S123

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

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

Chest wall volume receiving >30 Gy predicts risk of severe pain and/or rib fracture after lung stereotactic body radiotherapy.

PURPOSE: To identify the dose-volume parameters that predict the risk of chest wall (CW) pain and/or rib fracture after lung stereotactic body radiotherapy. METHODS AND MATERIALS: From a combined, larger multi-institution experience, 60 consecutive patients treated with three to five fractions of stereotactic body radiotherapy for primary or metastatic peripheral lung lesions were reviewed. CW pain was assessed using the Common Toxicity Criteria for pain. Peripheral lung lesions were defined as those located within 2.5 cm of the CW. A minimal point dose of 20 Gy to the CW was required. The CW volume receiving >or=20, >or=30, >or=40, >or=50, and >or=60 Gy was determined and related to the risk of CW toxicity. RESULTS: Of the 60 patients, 17 experienced Grade 3 CW pain and five rib fractures. The median interval to the onset of severe pain and/or fracture was 7.1 months. The risk of CW toxicity was fitted to the median effective concentration dose-response model. The CW volume receiving 30 Gy best predicted the risk of severe CW pain and/or rib fracture (R(2) = 0.9552). A volume threshold of 30 cm(3) was observed before severe pain and/or rib fracture was reported. A 30% risk of developing severe CW toxicity correlated with a CW volume of 35 cm(3) receiving 30 Gy. CONCLUSION: The development of CW toxicity is clinically relevant, and the CW should be considered an organ at risk in treatment planning. The CW volume receiving 30 Gy in three to five fractions should be limited to <30 cm(3), if possible, to reduce the risk of toxicity without compromising tumor coverage.

Authors
Dunlap, NE; Cai, J; Biedermann, GB; Yang, W; Benedict, SH; Sheng, K; Schefter, TE; Kavanagh, BD; Larner, JM
MLA Citation
Dunlap, NE, Cai, J, Biedermann, GB, Yang, W, Benedict, SH, Sheng, K, Schefter, TE, Kavanagh, BD, and Larner, JM. "Chest wall volume receiving >30 Gy predicts risk of severe pain and/or rib fracture after lung stereotactic body radiotherapy." Int J Radiat Oncol Biol Phys 76.3 (March 1, 2010): 796-801.
PMID
19427740
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
76
Issue
3
Publish Date
2010
Start Page
796
End Page
801
DOI
10.1016/j.ijrobp.2009.02.027

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

Pulmonary kinematics from tagged hyperpolarized helium-3 MRI

Purpose: To propose and test the feasibility of a novel method for quantifying 3D regional pulmonary kinematics from hyperpolarized helium-3 tagged MRI in human subjects using a tailored image processing pipeline and a recently developed nonrigid registration framework. Materials and Methods: Following image acquisition, inspiratory and expiratory tagged 3He magnetic resonance (MR) images were preprocessed using various image filtering techniques to enhance the tag surfaces. Segmentation of the three orthogonal sets of tag planes in each lung produced distinct point-set representations of the tag surfaces. Using these labeled point-sets, deformation fields and corresponding strain maps were obtained via nonrigid point-set registration. Kinematic analysis was performed on three volunteers. Results: Tag lines in inspiratory and expiratory images were coregistered producing a continuous 3D correspondence mapping. Average displacement and directional strains were calculated in three subjects in the inferior, mid, and superior portions of the right and left lungs. As expected, the predominant direction of displacements with expiration is from inferior to superior. Conclusion: Kinematic quantitation of pulmonary motion using tagged 3He MRI is feasible using the applied image preprocessing filtering techniques and nonrigid point-set registration. Potential benefits from regional pulmonary kinematic quantitation include the facilitation of diagnosis and local assessment of disease progression. © 2010 Wiley-Liss, Inc.

Authors
Tustison, NJ; Awate, SP; Cai, J; Altes, TA; Miller, GW; Lange, EED; III, JPM; Gee, JC
MLA Citation
Tustison, NJ, Awate, SP, Cai, J, Altes, TA, Miller, GW, Lange, EED, III, JPM, and Gee, JC. "Pulmonary kinematics from tagged hyperpolarized helium-3 MRI." Journal of Magnetic Resonance Imaging 31.5 (2010): 1236-1241.
PMID
20432362
Source
scival
Published In
Journal of Magnetic Resonance Imaging
Volume
31
Issue
5
Publish Date
2010
Start Page
1236
End Page
1241
DOI
10.1002/jmri.22137

SRT and SBRT: Current practices for QA dosimetry and 3D

The major feature that separates stereotactic radiation therapy (cranial SRT) and stereotactic body radiation therapy (SBRT) from conventional radiation treatment is the delivery of large doses in a few fractions which results in a high biological effective dose (BED). In order to minimize the normal tissue toxicity, quality assurance of the conformation of high doses to the target and rapid fall off doses away from the target is critical. The practice of SRT and SBRT therefore requires a high-level of confidence in the accuracy of the entire treatment delivery process. In SRT and SBRT confidence in this accuracy is accomplished by the integration of modern imaging, simulation, treatment planning and delivery technologies into all phases of the treatment process; from treatment simulation and planning and continuing throughout beam delivery. In this report some of the findings of Task group 101 of the AAPM will be presented which outlines the best-practice guidelines for SBRT. The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information in this task group is provided for establishing an SBRT program, including protocols, equipment, resources, and QA procedures. © 2010 IOP Publishing Ltd.

Authors
Benedict, SH; Cai, J; Libby, B; Lovelock, M; Schlesinger, D; Sheng, K; Yang, W
MLA Citation
Benedict, SH, Cai, J, Libby, B, Lovelock, M, Schlesinger, D, Sheng, K, and Yang, W. "SRT and SBRT: Current practices for QA dosimetry and 3D." Journal of Physics: Conference Series 250 (2010): 272-282.
Source
scival
Published In
Journal of Physics
Volume
250
Publish Date
2010
Start Page
272
End Page
282
DOI
10.1088/1742-6596/250/1/012057

A short-breath-hold technique for lung pO2 mapping with 3He MRI

A pulse-sequence strategy was developed for generating regional maps of alveolar oxygen partial pressure (pO2) in a single 6-sec breath hold, for use in human subjects with impaired lung function. Like previously described methods, pO2 values are obtained by measuring the oxygen-induced T1 relaxation of inhaled hyperpolarized 3He. Unlike other methods, only two 3He images are acquired: one with reverse-centric and the other with centric phase-encoding order. This phase-encoding arrangement minimizes the effects of regional flip-angle variations, so that an accurate map of instantaneous pO2 can be calculated from two images acquired a few seconds apart. By combining this phase-encoding strategy with variable flip angles, the vast majority of the hyperpolarized magnetization goes directly into the T1 measurement, minimizing noise in the resulting pO2 map. The short-breathhold pulse sequence was tested in phantoms containing known O2 concentrations. The mean difference between measured and prepared pO2 values was 1 mm Hg. The method was also tested in four healthy volunteers and three lung-transplant patients. Maps of healthy subjects were largely uniform, whereas focal regions of abnormal pO2 were observed in diseased subjects. Mean pO2 values varied with inhaled O2 concentration. Mean pO2 was consistent with normal steady-state values in subjects who inhaled 3He diluted only with room air. © 2009 Wiley-Liss, Inc.

Authors
Miller, GW; III, JPM; Altes, TA; Cai, J; Mata, JF; Lange, EED; Tobias, WA; Cates, GD; Brookeman, JR
MLA Citation
Miller, GW, III, JPM, Altes, TA, Cai, J, Mata, JF, Lange, EED, Tobias, WA, Cates, GD, and Brookeman, JR. "A short-breath-hold technique for lung pO2 mapping with 3He MRI." Magnetic Resonance in Medicine 63.1 (2010): 127-136.
PMID
19918891
Source
scival
Published In
Magnetic Resonance in Medicine
Volume
63
Issue
1
Publish Date
2010
Start Page
127
End Page
136
DOI
10.1002/mrm.22181

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

Dynamic MRI of grid-tagged hyperpolarized helium-3 for the assessment of lung motion during breathing.

PURPOSE: To develop a dynamic magnetic resonance imaging (MRI) tagging technique using hyperpolarized helium-3 (HP He-3) to track lung motion. METHODS AND MATERIALS: An accelerated non-Cartesian k-space trajectory was used to gain acquisition speed, at the cost of introducing image artifacts, providing a viable strategy for obtaining whole-lung coverage with adequate temporal resolution. Multiple-slice two-dimensional dynamic images of the lung were obtained in three healthy subjects after inhaling He-3 gas polarized to 35%-40%. Displacement, strain, and ventilation maps were computed from the observed motion of the grid peaks. RESULTS: Both temporal and spatial variations of pulmonary mechanics were observed in normal subjects, including shear motion between different lobes of the same lung. CONCLUSION: These initial results suggest that dynamic imaging of grid-tagged hyperpolarized magnetization may potentially be a powerful tool for observing and quantifying pulmonary biomechanics on a regional basis and for assessing, validating, and improving lung deformable image registration algorithms.

Authors
Cai, J; Sheng, K; Benedict, SH; Read, PW; Larner, JM; Mugler, JP; de Lange, EE; Cates, GD; Miller, GW
MLA Citation
Cai, J, Sheng, K, Benedict, SH, Read, PW, Larner, JM, Mugler, JP, de Lange, EE, Cates, GD, and Miller, GW. "Dynamic MRI of grid-tagged hyperpolarized helium-3 for the assessment of lung motion during breathing." Int J Radiat Oncol Biol Phys 75.1 (September 1, 2009): 276-284.
PMID
19540059
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
75
Issue
1
Publish Date
2009
Start Page
276
End Page
284
DOI
10.1016/j.ijrobp.2009.03.051

Tracking brain motion during the cardiac cycle using spiral cine-DENSE MRI.

Cardiac-synchronized brain motion is well documented, but the accurate measurement of such motion on the pixel-by-pixel basis has been hampered by the lack of proper imaging technique. In this article, the authors present the implementation of an autotracking spiral cine displacement-encoded stimulation echo (DENSE) magnetic resonance imaging (MRI) technique for the measurement of pulsatile brain motion during the cardiac cycle. Displacement-encoded dynamic MR images of three healthy volunteers were acquired throughout the cardiac cycle using the spiral cine-DENSE pulse sequence gated to the R wave of an electrocardiogram. Pixelwise Lagrangian displacement maps were computed, and 2D displacement as a function of time was determined for selected regions of interests. Different intracranial structures exhibited characteristic motion amplitude, direction, and pattern throughout the cardiac cycle. Time-resolved displacement curves revealed the pathway of pulsatile motion from brain stem to peripheral brain lobes. These preliminary results demonstrated that the spiral cine-DENSE MRI technique can be used to measure cardiac-synchronized pulsatile brain motion on the pixel-by-pixel basis with high temporal/spatial resolution and sensitivity.

Authors
Zhong, X; Meyer, CH; Schlesinger, DJ; Sheehan, JP; Epstein, FH; Larner, JM; Benedict, SH; Read, PW; Sheng, K; Cai, J
MLA Citation
Zhong, X, Meyer, CH, Schlesinger, DJ, Sheehan, JP, Epstein, FH, Larner, JM, Benedict, SH, Read, PW, Sheng, K, and Cai, J. "Tracking brain motion during the cardiac cycle using spiral cine-DENSE MRI." Med Phys 36.8 (August 2009): 3413-3419.
PMID
19746774
Source
pubmed
Published In
Medical physics
Volume
36
Issue
8
Publish Date
2009
Start Page
3413
End Page
3419
DOI
10.1118/1.3157109

A rabbit irradiation platform for outcome assessment of lung stereotactic radiosurgery.

PURPOSE: To evaluate a helical tomotherapy-based rodent radiosurgery platform that reproduces human image-guided radiosurgery treatment to study radiobiologic effects of stereotactic radiosurgery on lung tissues using functional magnetic resonance imaging (MRI). METHODS AND MATERIALS: Hypofractionated radisourgery (20 Gy x 3) was delivered to the right lung of three New Zealand rabbits using Helical TomoTherapy with MVCT image guidance. Contrast-enhanced MR perfusion, hyperpolarized helium-3 MR ventilation, and CT were obtained before radiation and monthly for 4 months after radiation. All MRI was performed on a 1.5-T whole-body scanner with broad-band capabilities. RESULTS: Precise dose delivery to 1.6 cc of the lower right lung was achieved without additional immobilization. No deficits were detected at baseline with respect to perfusion and ventilation. Lung perfusion deficits in the irradiated lung regions began at 2 months after radiation and worsened with time. No ventilation deficits were observed after radiation. Decrease in lung CT density in irradiated regions was observed after radiation, but the changes were less significant than those in perfusion MRI. CONCLUSIONS: We demonstrated that highly conformal radiation can be reproducibly delivered to a small volume of rodent lung on a widely available clinical unit. The radiation-induced lung injury can be detected as early as 2 months after radiation with perfusion MRI. The primary pattern of injury agrees with previously reported endothelial damage to radiosurgical radiation doses. This experimental design provides a cost-effective methodology for producing radiosurgical injuries in rodents that reproduces current human treatments for studying radiation injury and agents that might affect it.

Authors
Cai, J; Mata, JF; Orton, MD; Hagspiel, KD; Mugler, JP; Larner, JM; Sheng, K; Read, PW
MLA Citation
Cai, J, Mata, JF, Orton, MD, Hagspiel, KD, Mugler, JP, Larner, JM, Sheng, K, and Read, PW. "A rabbit irradiation platform for outcome assessment of lung stereotactic radiosurgery." Int J Radiat Oncol Biol Phys 73.5 (April 1, 2009): 1588-1595.
PMID
19306756
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
73
Issue
5
Publish Date
2009
Start Page
1588
End Page
1595
DOI
10.1016/j.ijrobp.2008.11.038

Reproducibility of interfraction lung motion probability distribution function using dynamic MRI: statistical analysis.

PURPOSE: To investigate the statistical reproducibility of craniocaudal probability distribution function (PDF) of interfraction lung motion using dynamic magnetic resonance imaging. METHODS AND MATERIALS: A total of 17 subjects, 9 healthy volunteers and 8 lung tumor patients, underwent two to three continuous 300-s magnetic resonance imaging scans in the sagittal plane, repeated 2 weeks apart. Three pulmonary vessels from different lung regions (upper, middle, and lower) in the healthy subjects and lung tumor patients were selected for tracking, and the displacement PDF reproducibility was evaluated as a function of scan time and frame rate. RESULTS: For both healthy subjects and patients, the PDF reproducibility improved with increased scan time and converged to an equilibrium state during the 300-s scan. The PDF reproducibility at 300 s (mean, 0.86; range, 0.70-0.96) were significantly (p < 0.001) increased compared with those at 5 s (mean, 0.65; range, 0.25-0.79). PDF reproducibility showed less sensitivity to imaging frame rates that were >2 frames/s. CONCLUSION: A statistically significant improvement in PDF reproducibility was observed with a prolonged scan time among the 17 participants. The confirmation of PDF reproducibility over times much shorter than stereotactic body radiotherapy delivery duration is a vital part of the initial validation process of probability-based treatment planning for stereotactic body radiotherapy for lung cancer.

Authors
Cai, J; Read, PW; Larner, JM; Jones, DR; Benedict, SH; Sheng, K
MLA Citation
Cai, J, Read, PW, Larner, JM, Jones, DR, Benedict, SH, and Sheng, K. "Reproducibility of interfraction lung motion probability distribution function using dynamic MRI: statistical analysis." Int J Radiat Oncol Biol Phys 72.4 (November 15, 2008): 1228-1235.
PMID
18954717
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
72
Issue
4
Publish Date
2008
Start Page
1228
End Page
1235
DOI
10.1016/j.ijrobp.2008.07.028

The effect of respiratory motion variability and tumor size on the accuracy of average intensity projection from four-dimensional computed tomography: an investigation based on dynamic MRI.

Composite images such as average intensity projection (AIP) and maximum intensity projection (MIP) derived from four-dimensional computed tomography (4D-CT) images are commonly used in radiation therapy for treating lung and abdominal tumors. It has been reported that the quality of 4D-CT images is influenced by the patient respiratory variability, which can be assessed by the standard deviation of the peak and valley of the respiratory trajectory. Subsequently, the resultant MIP underestimates the actual tumor motion extent. As a more general application, AIP comprises not only the tumor motion extent but also the probability that the tumor is present. AIP generated from 4D-CT can also be affected by the respiratory variability. To quantitate the accuracy of AIP and develop clinically relevant parameters for determining suitability of the 4D-CT study for AIP-based treatment planning, real time sagittal dynamic magnetic resonance imaging (dMRI) was used as the basis for generating simulated 4D-CT. Five-minute MRI scans were performed on seven healthy volunteers and eight lung tumor patients. In addition, images of circular phantoms with diameter 1, 3, or 5 cm were generated by software to simulate lung tumors. Motion patterns determined by dMRI images were reproduced by the software generated phantoms. Resorted dMRI using a 4D-CT acquisition method (RedCAM) based on phantom or patient images was reconstructed by simulating the imaging rebinning processes. AIP images and the corresponding color intensity projection (CIP) images were reconstructed from RedCAM and the full set of dMRI for comparison. AIP similarity indicated by the Dice index between RedCAM and dMRI was calculated and correlated with respiratory variability (v) and tumor size (s). The similarity of percentile intrafractional motion target area (IMTA), defined by the area that the tumor presented for a given percentage of time, and MIP-to-percentile IMTA similarity as a function of percentile were also determined. As a result, AIP similarity depends on both respiratory variability and tumor sizes. The AIP similarity correlated linearly with the respiratory variability normalized by tumor sizes (R2 equal to 0.82 and 0.91 for the phantom study and the patient study, respectively). For both studies, MIP derived from RedCAM was close to the area that the tumor presented 90% or more of the time and missed the region where the tumor appeared less than 10% of the time. In conclusion, the accuracy of composite images such as AIP and MIP derived from 4D-CT to define the tumor motion and position is affected by patient-specific respiratory variability and tumor sizes. Based on our study, normalized respiratory variability appears to be a pertinent parameter to assess the suitability of a 4D-CT image set for ALP-based treatment planning.

Authors
Cai, J; Read, PW; Sheng, K
MLA Citation
Cai, J, Read, PW, and Sheng, K. "The effect of respiratory motion variability and tumor size on the accuracy of average intensity projection from four-dimensional computed tomography: an investigation based on dynamic MRI." Med Phys 35.11 (November 2008): 4974-4981.
PMID
19070231
Source
pubmed
Published In
Medical physics
Volume
35
Issue
11
Publish Date
2008
Start Page
4974
End Page
4981
DOI
10.1118/1.2982245

Imaging the lung in radiotherapy: Where 4D meets multimodality

The increasing research and clinical interest in the intrafractional motion management of lung tumour radiation treatment is in part fuelled by the availability of multiple 4D modalities that resolve temporal information of the tumour motion. These improved imaging modalities allow the escalation of dose to the tumour besides enhancing the conformality of the dose to a moving tumour, which could improve the local control rate. Magnetic resonance imaging (MRI; including dynamic MRI and hyperpolarized 3He tagging), 4DCT, fluoroscopy and EM transponders are reviewed in this article. The working mechanisms, advantages/disadvantages and unique information of these techniques and their contribution to the management of lung cancer are discussed. © 2008 Blackwell Publishing Ltd.

Authors
Sheng, K; Cai, J; Libby, B; Benedict, S
MLA Citation
Sheng, K, Cai, J, Libby, B, and Benedict, S. "Imaging the lung in radiotherapy: Where 4D meets multimodality." Imaging Decisions MRI 12.1 (2008): 25-31.
Source
scival
Published In
Imaging Decisions MRI
Volume
12
Issue
1
Publish Date
2008
Start Page
25
End Page
31
DOI
10.1111/j.1617-0830.2008.00117.x

Point-set registration of tagged HE-3 images using a structurally-based Jensen-Shannon divergence measure within a deterministic annealing framework

Helium-3 tagged magnetic resonance imaging has demonstrated potential for calculating pulmonary deformation from medical imagery. Such measurements are useful for determining the biomechanical properties of the lung. Unfortunately, the relative facility of visually tracking deformation via the high contrast tag lines has not transferred readily to the algorithmic domain of automatically establishing tag-line correspondences. We proffer a solution to this dilemma by translating the problem into a unique point-set registration scenario. Not only does this permit capitalizing on certain spectral aspects of tagged MRI but registration can be performed within a deterministic annealing framework for decreased susceptibility to local minima. ©2008 IEEE.

Authors
Tustison, NJ; Awate, SP; Altes, TA; Gee, JC; Cai, J; Miller, GW; Lange, EED; III, JPM
MLA Citation
Tustison, NJ, Awate, SP, Altes, TA, Gee, JC, Cai, J, Miller, GW, Lange, EED, and III, JPM. "Point-set registration of tagged HE-3 images using a structurally-based Jensen-Shannon divergence measure within a deterministic annealing framework." 2008 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, Proceedings, ISBI (2008): 772-775.
Source
scival
Published In
2008 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, Proceedings, ISBI
Publish Date
2008
Start Page
772
End Page
775
DOI
10.1109/ISBI.2008.4541110

Estimation of error in maximal intensity projection-based internal target volume of lung tumors: a simulation and comparison study using dynamic magnetic resonance imaging.

PURPOSE: To evaluate the error in four-dimensional computed tomography (4D-CT) maximal intensity projection (MIP)-based lung tumor internal target volume determination using a simulation method based on dynamic magnetic resonance imaging (dMRI). METHODS AND MATERIALS: Eight healthy volunteers and six lung tumor patients underwent a 5-min MRI scan in the sagittal plane to acquire dynamic images of lung motion. A MATLAB program was written to generate re-sorted dMRI using 4D-CT acquisition methods (RedCAM) by segmenting and rebinning the MRI scans. The maximal intensity projection images were generated from RedCAM and dMRI, and the errors in the MIP-based internal target area (ITA) from RedCAM (epsilon), compared with those from dMRI, were determined and correlated with the subjects' respiratory variability (nu). RESULTS: Maximal intensity projection-based ITAs from RedCAM were comparatively smaller than those from dMRI in both phantom studies (epsilon = -21.64% +/- 8.23%) and lung tumor patient studies (epsilon = -20.31% +/- 11.36%). The errors in MIP-based ITA from RedCAM correlated linearly (epsilon = -5.13nu - 6.71, r(2) = 0.76) with the subjects' respiratory variability. CONCLUSIONS: Because of the low temporal resolution and retrospective re-sorting, 4D-CT might not accurately depict the excursion of a moving tumor. Using a 4D-CT MIP image to define the internal target volume might therefore cause underdosing and an increased risk of subsequent treatment failure. Patient-specific respiratory variability might also be a useful predictor of the 4D-CT-induced error in MIP-based internal target volume determination.

Authors
Cai, J; Read, PW; Baisden, JM; Larner, JM; Benedict, SH; Sheng, K
MLA Citation
Cai, J, Read, PW, Baisden, JM, Larner, JM, Benedict, SH, and Sheng, K. "Estimation of error in maximal intensity projection-based internal target volume of lung tumors: a simulation and comparison study using dynamic magnetic resonance imaging." Int J Radiat Oncol Biol Phys 69.3 (November 1, 2007): 895-902.
PMID
17889270
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
69
Issue
3
Publish Date
2007
Start Page
895
End Page
902
DOI
10.1016/j.ijrobp.2007.07.2322

MR grid-tagging using hyperpolarized helium-3 for regional quantitative assessment of pulmonary biomechanics and ventilation.

A new technique is demonstrated in six healthy human subjects that combines grid-tagging and hyperpolarized helium-3 MRI to assess regional lung biomechanical function and quantitative ventilation. 2D grid-tagging, achieved by applying sinc-modulated RF-pulse trains along the frequency- and phase-encoding directions, was followed by a multislice fast low-angle shot (FLASH)-based acquisition at inspiration and expiration. The displacement vectors, first and second principal strains, and quantitative ventilation were computed, and mean values were calculated for the upper, middle, and lower lung regions. Displacements in the lower region were significantly greater than those in either the middle or upper region (P < 0.005), while there were no significant differences between the three regions for the two principal strains and quantitative ventilation (P = 0.11-0.92). Variations in principal strains and ventilation were greater between subjects than between lung zones within individual subjects. This technique has the potential to provide insight into regional biomechanical alterations of lung function in a variety of lung diseases.

Authors
Cai, J; Altes, TA; Miller, GW; Sheng, K; Read, PW; Mata, JF; Zhong, X; Cates, GD; de Lange, EE; Mugler, JP; Brookeman, JR
MLA Citation
Cai, J, Altes, TA, Miller, GW, Sheng, K, Read, PW, Mata, JF, Zhong, X, Cates, GD, de Lange, EE, Mugler, JP, and Brookeman, JR. "MR grid-tagging using hyperpolarized helium-3 for regional quantitative assessment of pulmonary biomechanics and ventilation." Magn Reson Med 58.2 (August 2007): 373-380.
PMID
17654579
Source
pubmed
Published In
Magnetic Resonance in Medicine
Volume
58
Issue
2
Publish Date
2007
Start Page
373
End Page
380
DOI
10.1002/mrm.21288

Dose as a function of lung volume and planned treatment volume in helical tomotherapy intensity-modulated radiation therapy-based stereotactic body radiation therapy for small lung tumors.

PURPOSE: To evaluate the limitations of Hi-Art Helical Tomotherapy (Middleton, WI) stereotactic body radiotherapy (SBRT) for lung lesions, and to provide an initial report on patients treated with this method. Stereotactic body radiotherapy was shown to be an effective, well-tolerated treatment for early-stage, non-small-cell lung carcinoma (NSCLC). The Radiation Therapy Oncology Group (RTOG) 0236 protocol is currently evaluating three-dimensional conformal SBRT that delivers 60 Gy in three fractions. METHODS AND MATERIALS: Inverse treatment planning for hypothetical lung gross tumor volumes (GTV) and planned treatment volume (PTV) expansions were performed. We tested the hypothesis that the maximum acceptable dose (MAD) to be delivered to the lesion by SBRT could be predicted by PTV and lung volume. Dose constraints on normal tissue were as designated by the RTOG protocol. Inverse planning was performed to find the maximum tolerated SBRT dose up to 60 Gy. RESULTS: Regression analysis of the data obtained indicated a linear relationship between MAD, PTV, and lung volume. This generated two equations which may be useful predictive tools. Seven patients with Stage I and II NSCLC treated at the University of Virginia with this method tolerated the treatment extremely well, and suffered no greater than grade I toxicity, with no evidence of disease recurrence in follow-up from 2-20 months. CONCLUSIONS: Helical tomotherapy SBRT for lung lesions is well-tolerated. In addition, the likely MAD for patients considered for this type of treatment can be predicted by PTV and lung volume.

Authors
Baisden, JM; Romney, DA; Reish, AG; Cai, J; Sheng, K; Jones, DR; Benedict, SH; Read, PW; Larner, JM
MLA Citation
Baisden, JM, Romney, DA, Reish, AG, Cai, J, Sheng, K, Jones, DR, Benedict, SH, Read, PW, and Larner, JM. "Dose as a function of lung volume and planned treatment volume in helical tomotherapy intensity-modulated radiation therapy-based stereotactic body radiation therapy for small lung tumors." Int J Radiat Oncol Biol Phys 68.4 (July 15, 2007): 1229-1237.
PMID
17513066
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
68
Issue
4
Publish Date
2007
Start Page
1229
End Page
1237
DOI
10.1016/j.ijrobp.2007.03.024

Direct measurement of lung motion using hyperpolarized helium-3 MR tagging.

PURPOSE: To measure lung motion between end-inhalation and end-exhalation using a hyperpolarized helium-3 (HP (3)He) magnetic resonance (MR) tagging technique. METHODS AND MATERIALS: Three healthy volunteers underwent MR tagging studies after inhalation of 1 L HP (3)He gas diluted with nitrogen. Multiple-slice two-dimensional and volumetric three-dimensional MR tagged images of the lungs were obtained at end-inhalation and end-exhalation, and displacement vector maps were computed. RESULTS: The grids of tag lines in the HP (3)He MR images were well defined at end-inhalation and remained evident at end-exhalation. Displacement vector maps clearly demonstrated the regional lung motion and deformation that occurred during exhalation. Discontinuity and differences in motion pattern between two adjacent lung lobes were readily resolved. CONCLUSIONS: Hyperpolarized helium-3 MR tagging technique can be used for direct in vivo measurement of respiratory lung motion on a regional basis. This technique may lend new insights into the regional pulmonary biomechanics and thus provide valuable information for the deformable registration of lung.

Authors
Cai, J; Miller, GW; Altes, TA; Read, PW; Benedict, SH; de Lange, EE; Cates, GD; Brookeman, JR; Mugler, JP; Sheng, K
MLA Citation
Cai, J, Miller, GW, Altes, TA, Read, PW, Benedict, SH, de Lange, EE, Cates, GD, Brookeman, JR, Mugler, JP, and Sheng, K. "Direct measurement of lung motion using hyperpolarized helium-3 MR tagging." Int J Radiat Oncol Biol Phys 68.3 (July 1, 2007): 650-653.
PMID
17445997
Source
pubmed
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
68
Issue
3
Publish Date
2007
Start Page
650
End Page
653
DOI
10.1016/j.ijrobp.2007.02.011

Evaluation of emphysema severity and progression in a rabbit model: comparison of hyperpolarized 3He and 129Xe diffusion MRI with lung morphometry.

The apparent diffusion coefficients (ADCs) of hyperpolarized (3)He and (129)Xe gases were measured in the lungs of rabbits with elastase-induced emphysema and correlated against the mean chord length from lung histology. In vivo measurements were performed at baseline and 2, 4, 6, and 8 wk after instillation of elastase (mild and moderate emphysema groups) or saline (control group). ADCs were determined from acquisitions that used two b values. To investigate the effect of b value on the results, b-value pairs of 0 and 1.6 s/cm(2) and 0 and 4.0 s/cm(2) were used for (3)He, and b-value pairs of 0 and 5.0 s/cm(2) and 0 and 10.0 s/cm(2) were used for (129)Xe. At 8 wk after instillation, the rabbits were euthanized, and the lungs were analyzed histologically and morphometrically. ADCs for the rabbits in the control group did not change significantly from baseline to week 8, whereas ADCs for the rabbits in the emphysema groups increased significantly (P < 0.05) for all gas and b-value combinations except (129)Xe with the b-value pair of 0 and 5.0 s/cm(2). The largest percent change in mean ADC from baseline to week 8 (15.3%) occurred with (3)He and the b-value pair of 0 and 1.6 s/cm(2) for rabbits in the moderate emphysema group. ADCs (all b values) were strongly correlated (r = 0.62-0.80, P < 0.001) with mean chord lengths from histology. These results further support the ability of diffusion-weighted MRI with hyperpolarized gases to detect regional and global structural changes of emphysema within the lung.

Authors
Mata, JF; Altes, TA; Cai, J; Ruppert, K; Mitzner, W; Hagspiel, KD; Patel, B; Salerno, M; Brookeman, JR; de Lange, EE; Tobias, WA; Wang, H-TJ; Cates, GD; Mugler, JP
MLA Citation
Mata, JF, Altes, TA, Cai, J, Ruppert, K, Mitzner, W, Hagspiel, KD, Patel, B, Salerno, M, Brookeman, JR, de Lange, EE, Tobias, WA, Wang, H-TJ, Cates, GD, and Mugler, JP. "Evaluation of emphysema severity and progression in a rabbit model: comparison of hyperpolarized 3He and 129Xe diffusion MRI with lung morphometry." J Appl Physiol (1985) 102.3 (March 2007): 1273-1280.
PMID
17110518
Source
pubmed
Published In
Journal of applied physiology (Bethesda, Md. : 1985)
Volume
102
Issue
3
Publish Date
2007
Start Page
1273
End Page
1280
DOI
10.1152/japplphysiol.00418.2006

Evaluation of the reproducibility of lung motion probability distribution function (PDF) using dynamic MRI.

Treatment planning based on probability distribution function (PDF) of patient geometries has been shown a potential off-line strategy to incorporate organ motion, but the application of such approach highly depends upon the reproducibility of the PDF. In this paper, we investigated the dependences of the PDF reproducibility on the imaging acquisition parameters, specifically the scan time and the frame rate. Three healthy subjects underwent a continuous 5 min magnetic resonance (MR) scan in the sagittal plane with a frame rate of approximately 10 f s-1, and the experiments were repeated with an interval of 2 to 3 weeks. A total of nine pulmonary vessels from different lung regions (upper, middle and lower) were tracked and the dependences of their displacement PDF reproducibility were evaluated as a function of scan time and frame rate. As results, the PDF reproducibility error decreased with prolonged scans and appeared to approach equilibrium state in subjects 2 and 3 within the 5 min scan. The PDF accuracy increased in the power function with the increase of frame rate; however, the PDF reproducibility showed less sensitivity to frame rate presumably due to the randomness of breathing which dominates the effects. As the key component of the PDF-based treatment planning, the reproducibility of the PDF affects the dosimetric accuracy substantially. This study provides a reference for acquiring MR-based PDF of structures in the lung.

Authors
Cai, J; Read, PW; Altes, TA; Molloy, JA; Brookeman, JR; Sheng, K
MLA Citation
Cai, J, Read, PW, Altes, TA, Molloy, JA, Brookeman, JR, and Sheng, K. "Evaluation of the reproducibility of lung motion probability distribution function (PDF) using dynamic MRI." Phys Med Biol 52.2 (January 21, 2007): 365-373.
PMID
17202620
Source
pubmed
Published In
Physics in Medicine and Biology
Volume
52
Issue
2
Publish Date
2007
Start Page
365
End Page
373
DOI
10.1088/0031-9155/52/2/004

Evaluation of thoracic spinal cord motion using dynamic MRI

The aim of study was to assess the thoracic spinal cord motion during normal breathing using dynamic magnetic resonance imaging (dMRI). We found that the mean motion range at different thoracic levels is typically within 0.5 mm. The good stability makes this an excellent position for stereotactic radiotherapy (SBRT). © 2007 Elsevier Ireland Ltd. All rights reserved.

Authors
Cai, J; Sheng, K; Sheehan, JP; Benedict, SH; Larner, JM; Read, PW
MLA Citation
Cai, J, Sheng, K, Sheehan, JP, Benedict, SH, Larner, JM, and Read, PW. "Evaluation of thoracic spinal cord motion using dynamic MRI." Radiotherapy and Oncology 84.3 (2007): 279-282.
PMID
17692979
Source
scival
Published In
Radiotherapy & Oncology
Volume
84
Issue
3
Publish Date
2007
Start Page
279
End Page
282
DOI
10.1016/j.radonc.2007.06.008

Pulmonary kinematics from hyperpolarized helium-3 tagged magnetic resonance imaging

Recent innovations in hyperpolarized Helium-3 magnetic resonance imaging (MRI) include the employment of MR tagging techniques for assessment of pulmonary deformation. Historically, such tagging methods have been successfully applied to cardiac research inspiring the development of computational techniques for the quantitative analysis of myocardial deformation. We present related research which concerns the calculation of kinematic quantities, such as displacement and strain, in the lung. Utilizing the high contrast tag lines as landmarks in the images and a recently developed fast n-D B-spline approximation algorithm, we fit a parametric object to the sparse tag line data to smoothly interpolate the underlying deformation field and, subsequently, extract lung kinematic information. We present results from a single human volunteer. © 2007 IEEE.

Authors
Tustison, NJ; Altes, TA; Gee, JC; Cai, J; Lange, EED; III, JPM
MLA Citation
Tustison, NJ, Altes, TA, Gee, JC, Cai, J, Lange, EED, and III, JPM. "Pulmonary kinematics from hyperpolarized helium-3 tagged magnetic resonance imaging." 2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - Proceedings (2007): 368-371.
Source
scival
Published In
2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - Proceedings
Publish Date
2007
Start Page
368
End Page
371
DOI
10.1109/ISBI.2007.356865

A computer simulated phantom study of tomotherapy dose optimization based on probability density functions (PDF) and potential errors caused by low reproducibility of PDF.

Lung tumor motion trajectories measured by four-dimensional CT or dynamic MRI can be converted to a probability density function (PDF), which describes the probability of the tumor at a certain position, for PDF based treatment planning. Using this method in simulated sequential tomotherapy, we study the dose reduction of normal tissues and more important, the effect of PDF reproducibility on the accuracy of dosimetry. For these purposes, realistic PDFs were obtained from two dynamic MRI scans of a healthy volunteer within a 2 week interval. The first PDF was accumulated from a 300 s scan and the second PDF was calculated from variable scan times from 5 s (one breathing cycle) to 300 s. Optimized beam fluences based on the second PDF were delivered to the hypothetical gross target volume (GTV) of a lung phantom that moved following the first PDF The reproducibility between two PDFs varied from low (78%) to high (94.8%) when the second scan time increased from 5 s to 300 s. When a highly reproducible PDF was used in optimization, the dose coverage of GTV was maintained; phantom lung receiving 10%-20% prescription dose was reduced by 40%-50% and the mean phantom lung dose was reduced by 9.6%. However, optimization based on PDF with low reproducibility resulted in a 50% underdosed GTV. The dosimetric error increased nearly exponentially as the PDF error increased. Therefore, although the dose of the tumor surrounding tissue can be theoretically reduced by PDF based treatment planning, the reliability and applicability of this method highly depend on if a reproducible PDF exists and is measurable. By correlating the dosimetric error and PDF error together, a useful guideline for PDF data acquisition and patient qualification for PDF based planning can be derived.

Authors
Sheng, K; Cai, J; Brookeman, J; Molloy, J; Christopher, J; Read, P
MLA Citation
Sheng, K, Cai, J, Brookeman, J, Molloy, J, Christopher, J, and Read, P. "A computer simulated phantom study of tomotherapy dose optimization based on probability density functions (PDF) and potential errors caused by low reproducibility of PDF." Med Phys 33.9 (September 2006): 3321-3326.
PMID
17022227
Source
pubmed
Published In
Medical physics
Volume
33
Issue
9
Publish Date
2006
Start Page
3321
End Page
3326
DOI
10.1118/1.2222331
Show More