To analyze the correlation between dose-volume-histograms (DVHs) with three patterns (edema, enhancement, and necrosis) of temporal lobe injury (TLI) in patients receiving intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and to determine optimal thresholds to predict the incidence of each TLI pattern, with particular emphasis on the relationship between edema volume and the risk of enhancement and necrosis.A cohort of 4186 NPC patients treated with IMRT was retrospectively reviewed with TLI presenting in 188 patients. The atlases of complication incidence (ACI) for each pattern were constructed using DVH curves of temporal lobes. Optimal threshold for predicting incidence of each pattern was determined using the point closest to top-left of the plot. The accuracy of using edema volume to predict enhancement and necrosis incidence was evaluated via area under curve (AUC) of receiver operator characteristics (ROC).All DVH parameters, Dmean, Dmax, D0.25cc, D0.5cc, D1cc, D3cc, D6cc, V20Gy, V30Gy, V40Gy, V50Gy, V60Gy, and V70Gy, except Dmin showed statistically significant differences between subgroups of each pattern (p < 0.05). For predicting incidence of each pattern, optimal DVH thresholds over the range of D0.25-D1cc, Dmean and V20-V70 were derived. The optimal thresholds of edema volume for predicting enhancement were 0.96 and 2.2cc and for predicting necrosis were 0.94 and 11.5cc.Optimal DVH thresholds were generated for limiting risk of each injury pattern. Edema volume was a strong predictor for risk of enhancement and necrosis, which could potentially be reduced by lowering edema volume below threshold.

Authors

Lu, L; Sheng, Y; Zhang, G; Li, Y; OuYang, P-Y; Ge, Y; Xie, T; Chang, H; Deng, X; Wu, JQ

MLA Citation

Lu, L, Sheng, Y, Zhang, G, Li, Y, OuYang, P-Y, Ge, Y, Xie, T, Chang, H, Deng, X, and Wu, JQ. "Temporal lobe injury patterns following intensity modulated radiotherapy in a large cohort of nasopharyngeal carcinoma patients." Oral Oncology 85 (October 2018): 8-14.

PMID

30220323

Source

epmc

Published In

Oral Oncology

Volume

85

Publish Date

2018

Start Page

8

End Page

14

DOI

10.1016/j.oraloncology.2018.07.020

With the era of big data, the utilization of machine learning algorithms in radiation oncology is rapidly growing with applications including: treatment response modeling, treatment planning, contouring, organ segmentation, image-guidance, motion tracking, quality assurance, and more. Despite this interest, practical clinical implementation of machine learning as part of the day-to-day clinical operations is still lagging. The aim of this white paper is to further promote progress in this new field of machine learning in radiation oncology by highlighting its untapped advantages and potentials for clinical advancement, while also presenting current challenges and open questions for future research. The targeted audience of this paper includes newcomers as well as practitioners in the field of medical physics/radiation oncology. The paper also provides general recommendations to avoid common pitfalls when applying these powerful data analytic tools to medical physics and radiation oncology problems and suggests some guidelines for transparent and informative reporting of machine learning results.

Authors

El Naqa, I; Ruan, D; Valdes, G; Dekker, A; McNutt, T; Ge, Y; Wu, QJ; Oh, JH; Thor, M; Smith, W; Rao, A; Fuller, C; Xiao, Y; Manion, F; Schipper, M; Mayo, C; Moran, JM; Ten Haken, R

MLA Citation

El Naqa, I, Ruan, D, Valdes, G, Dekker, A, McNutt, T, Ge, Y, Wu, QJ, Oh, JH, Thor, M, Smith, W, Rao, A, Fuller, C, Xiao, Y, Manion, F, Schipper, M, Mayo, C, Moran, JM, and Ten Haken, R. "Machine learning and modeling: Data, validation, communication challenges." Medical Physics 45.10 (October 2018): e834-e840.

PMID

30144098

Source

epmc

Published In

Medical Physics

Volume

45

Issue

10

Publish Date

2018

Start Page

e834

End Page

e840

DOI

10.1002/mp.12811

Beam angle configuration is a major planning decision in intensity modulated radiation treatment (IMRT) that has a significant impact on dose distributions and thus quality of treatment, especially in complex planning cases such as those for lung cancer treatment. We propose a novel method to automatically determine beam configurations that incorporates noncoplanar beams. We then present a completely automated IMRT planning algorithm that combines the proposed method with a previously reported OAR DVH prediction model. Finally, we validate this completely automatic planning algorithm using a set of challenging lung IMRT cases. A beam efficiency index map is constructed to guide the selection of beam angles. This index takes into account both the dose contributions from individual beams and the combined effect of multiple beams by introducing a beam-spread term. The effect of the beam-spread term on plan quality was studied systematically and the weight of the term to balance PTV dose conformity against OAR avoidance was determined. For validation, complex lung cases with clinical IMRT plans that required the use of one or more noncoplanar beams were re-planned with the proposed automatic planning algorithm. Important dose metrics for the PTV and OARs in the automatic plans were compared with those of the clinical plans. The results are very encouraging. The PTV dose conformity and homogeneity in the automatic plans improved significantly. And all the dose metrics of the automatic plans, except the lung V5 Gy, were statistically better than or comparable with those of the clinical plans. In conclusion, the automatic planning algorithm can incorporate non-coplanar beam configurations in challenging lung cases and can generate plans efficiently with quality closely approximating that of clinical plans.

Authors

Yuan, L; Zhu, W; Ge, Y; Jiang, Y; Sheng, Y; Yin, F-F; Wu, QJ

MLA Citation

Yuan, L, Zhu, W, Ge, Y, Jiang, Y, Sheng, Y, Yin, F-F, and Wu, QJ. "Lung IMRT planning with automatic determination of beam angle configurations." Physics in Medicine and Biology 63.13 (July 6, 2018): 135024-null.

PMID

29846178

Source

epmc

Published In

Physics in Medicine and Biology

Volume

63

Issue

13

Publish Date

2018

Start Page

135024

DOI

10.1088/1361-6560/aac8b4

To use knowledge-based planning (KBP) as a method of producing high-quality, consistent, protocol-compliant treatment plans in a complex setting of spine stereotactic body radiation therapy on NRG Oncology Radiation Therapy Oncology Group (RTOG) 0631.An internally developed KBP model was applied to an external validation cohort of 22 anonymized cases submitted under NRG Oncology RTOG 0631. The original and KBP plans were compared via their protocol compliance, target conformity and gradient index, dose to critical structures, and dose to surrounding normal tissues.The KBP model generated plans meeting all protocol objectives in a single optimization when tested on both internal and protocol-submitted NRG Oncology RTOG 0631 cases. Two submitted plans that were considered to have a protocol-unacceptable deviation were made protocol compliant through the use of the model. There were no statistically significant differences in protocol spinal cord metrics (D10% and D0.03cc) between the manually optimized plans and the KBP plans. The volume of planning target volume receiving prescription dose increased from 93.3% ± 3.2% to 98.3% ± 1.4% (P = .01) when using KBP. High-dose spillage to surrounding normal tissues (V105%) showed no significant differences (2.1 ± 7.3 cm3 for manual plans to 1.8 ± 0.6 cm3 with KBP), and dosimetric outliers with large amounts of spillage were eliminated through the use of KBP. Knowledge-based planning plans were also found to be significantly more consistent in several metrics, including target coverage and high dose outside of the target.Incorporation of KBP models into the clinical trial setting may have a profound impact on the quality of trial results, owing to the increase in consistency and standardization of planning, especially for treatment sites or techniques that are nonstandard.

Authors

Younge, KC; Marsh, RB; Owen, D; Geng, H; Xiao, Y; Spratt, DE; Foy, J; Suresh, K; Wu, QJ; Yin, F-F; Ryu, S; Matuszak, MM

MLA Citation

Younge, KC, Marsh, RB, Owen, D, Geng, H, Xiao, Y, Spratt, DE, Foy, J, Suresh, K, Wu, QJ, Yin, F-F, Ryu, S, and Matuszak, MM. "Improving Quality and Consistency in NRG Oncology Radiation Therapy Oncology Group 0631 for Spine Radiosurgery via Knowledge-Based Planning." International Journal of Radiation Oncology, Biology, Physics 100.4 (March 2018): 1067-1074.

PMID

29485048

Source

epmc

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

100

Issue

4

Publish Date

2018

Start Page

1067

End Page

1074

DOI

10.1016/j.ijrobp.2017.12.276

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

Authors

Sheng, Y; Li, T; Lee, WR; Yin, F-F; Wu, QJ

MLA Citation

Sheng, Y, Li, T, Lee, WR, Yin, F-F, and Wu, QJ. "Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis." International journal of radiation oncology, biology, physics 98.2 (June 2017): 473-480.

PMID

28463167

Source

epmc

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

98

Issue

2

Publish Date

2017

Start Page

473

End Page

480

DOI

10.1016/j.ijrobp.2017.02.089

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

Authors

Li, T; Wu, QJ; Matzen, T; Yin, F-F; O'Daniel, JC

MLA Citation

Li, T, Wu, QJ, Matzen, T, Yin, F-F, and O'Daniel, JC. "Diode-based transmission detector for IMRT delivery monitoring: a validation study." Journal of applied clinical medical physics 17.5 (September 2016): 1-10.

PMID

28297448

Source

epmc

Published In

Journal of Applied Clinical Medical Physics

Volume

17

Issue

5

Publish Date

2016

Start Page

1

End Page

10

DOI

10.1120/jacmp.v17i5.6204

To establish the feasibility of the dosimetric compliance criteria of the RTOG 1308 trial through testing against Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans.Twenty-six lung IMRT and 26 proton PSPT plans were included in the study. Dose Volume Histograms (DVHs) for targets and normal structures were analyzed. The quality of IMRT plans was assessed using a knowledge-based engineering tool.Most of the RTOG 1308 dosimetric criteria were achieved. The deviation unacceptable rates were less than 10 % for most criteria; however, a deviation unacceptable rate of more than 20 % was computed for the planning target volume minimum dose compliance criterion. Dose parameters for the target volume were very close for the IMRT and PSPT plans. However, the PSPT plans led to lower dose values for normal structures. The dose parameters in which PSPT plans resulted in lower values than IMRT plans were: lung V5Gy (%) (34.4 in PSPT and 47.2 in IMRT); maximum spinal cord dose (31.7 Gy in PSPT and 43.5 Gy in IMRT); heart V5Gy (%) (19 in PSPT and 47 in IMRT); heart V30Gy (%) (11 in PSPT and 19 in IMRT); heart V45Gy (%) (7.8 in PSPT and 12.1 in IMRT); heart V50% (Gy) (7.1 in PSPT and 9.8 in IMRT) and mean heart dose (7.7 Gy in PSPT and 14.9 Gy in IMRT).The revised RTOG 1308 dosimetric compliance criteria are feasible and achievable.

Authors

Giaddui, T; Chen, W; Yu, J; Lin, L; Simone, CB; Yuan, L; Gong, YUT; Wu, QJ; Mohan, R; Zhang, X; Bluett, JB; Gillin, M; Moore, K; O'Meara, E; Presley, J; Bradley, JD; Liao, Z; Galvin, J; Xiao, Y

MLA Citation

Giaddui, T, Chen, W, Yu, J, Lin, L, Simone, CB, Yuan, L, Gong, YUT, Wu, QJ, Mohan, R, Zhang, X, Bluett, JB, Gillin, M, Moore, K, O'Meara, E, Presley, J, Bradley, JD, Liao, Z, Galvin, J, and Xiao, Y. "Establishing the feasibility of the dosimetric compliance criteria of RTOG 1308: phase III randomized trial comparing overall survival after photon versus proton radiochemotherapy for inoperable stage II-IIIB NSCLC." Radiation Oncology (London, England) 11 (May 4, 2016): 66-null.

PMID

27142674

Source

epmc

Published In

Radiation Oncology

Volume

11

Publish Date

2016

Start Page

66

DOI

10.1186/s13014-016-0640-8

Authors

Godfrey, DJ; Ren, L; Wu, QJ; Yin, FF

MLA Citation

Godfrey, DJ, Ren, L, Wu, QJ, and Yin, FF. "Tomosynthesis applications in radiation oncology." Tomosynthesis Imaging. April 19, 2016. 199-212.

Source

scopus

Publish Date

2016

Start Page

199

End Page

212

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

Authors

Sheng, Y; Li, T; Zhang, Y; Lee, WR; Yin, F-F; Ge, Y; Wu, QJ

MLA Citation

Sheng, Y, Li, T, Zhang, Y, Lee, WR, Yin, F-F, Ge, Y, and Wu, QJ. "Atlas-guided prostate intensity modulated radiation therapy (IMRT) planning." Physics in medicine and biology 60.18 (September 8, 2015): 7277-7291.

PMID

26348663

Source

epmc

Published In

Physics in Medicine and Biology

Volume

60

Issue

18

Publish Date

2015

Start Page

7277

End Page

7291

DOI

10.1088/0031-9155/60/18/7277

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

Authors

Stanhope, C; Wu, QJ; Yuan, L; Liu, J; Hood, R; Yin, F-F; Adamson, J

MLA Citation

Stanhope, C, Wu, QJ, Yuan, L, Liu, J, Hood, R, Yin, F-F, and Adamson, J. "Utilizing knowledge from prior plans in the evaluation of quality assurance." Physics in Medicine and Biology 60.12 (June 9, 2015): 4873-4891.

PMID

26056801

Source

epmc

Published In

Physics in Medicine and Biology

Volume

60

Issue

12

Publish Date

2015

Start Page

4873

End Page

4891

DOI

10.1088/0031-9155/60/12/4873

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

Authors

Yuan, L; Wu, QJ; Yin, F; Li, Y; Sheng, Y; Kelsey, CR; Ge, Y

MLA Citation

Yuan, L, Wu, QJ, Yin, F, Li, Y, Sheng, Y, Kelsey, CR, and Ge, Y. "Standardized beam bouquets for lung IMRT planning." Physics in Medicine and Biology 60.5 (March 2015): 1831-1843.

PMID

25658486

Source

epmc

Published In

Physics in Medicine and Biology

Volume

60

Issue

5

Publish Date

2015

Start Page

1831

End Page

1843

DOI

10.1088/0031-9155/60/5/1831

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

Authors

Liu, J; Wu, QJ; Kirkpatrick, JP; Yin, F-F; Yuan, L; Ge, Y

MLA Citation

Liu, J, Wu, QJ, Kirkpatrick, JP, Yin, F-F, Yuan, L, and Ge, Y. "From active shape model to active optical flow model: a shape-based approach to predicting voxel-level dose distributions in spine SBRT." Physics in medicine and biology 60.5 (March 2015): N83-N92.

PMID

25675394

Source

epmc

Published In

Physics in Medicine and Biology

Volume

60

Issue

5

Publish Date

2015

Start Page

N83

End Page

N92

DOI

10.1088/0031-9155/60/5/n83

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

Authors

Li, Y; Rodrigues, A; Li, T; Yuan, L; Yin, F-F; Wu, QJ

MLA Citation

Li, Y, Rodrigues, A, Li, T, Yuan, L, Yin, F-F, and Wu, QJ. "Impact of dose calculation accuracy during optimization on lung IMRT plan quality." Journal of applied clinical medical physics 16.1 (January 8, 2015): 5137-.

PMID

25679172

Source

epmc

Published In

Journal of Applied Clinical Medical Physics

Volume

16

Issue

1

Publish Date

2015

Start Page

5137

DOI

10.1120/jacmp.v16i1.5137

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

Authors

Liu, J; Wu, QJ; Yin, FF; Kirkpatrick, JP; Cabrera, A; Ge, Y

MLA Citation

Liu, J, Wu, QJ, Yin, FF, Kirkpatrick, JP, Cabrera, A, and Ge, Y. "An active optical flow model for dose prediction in spinal SBRT plans." January 1, 2015.

Source

scopus

Published In

Lecture Notes in Engineering and Computer Science

Volume

20

Publish Date

2015

Start Page

27

End Page

35

DOI

10.1007/978-3-319-14148-0-3

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

Authors

Liu, J; Jackie Wu, Q; Yin, FF; Kirkpatrick, JP; Cabrera, A; Ge, Y

MLA Citation

Liu, J, Jackie Wu, Q, Yin, FF, Kirkpatrick, JP, Cabrera, A, and Ge, Y. "An active optical flow model for dose prediction in spinal sbrt plans." Lecture Notes in Computational Vision and Biomechanics 20 (January 1, 2015): 27-35.

Source

scopus

Published In

Lecture Notes in Computational Vision and Biomechanics

Volume

20

Publish Date

2015

Start Page

27

End Page

35

DOI

10.1007/978-3-319-14148-0_3

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

Authors

Yang, Y; Li, T; Yuan, L; Ge, Y; Yin, FF; Lee, WR; Wu, QJ

MLA Citation

Yang, Y, Li, T, Yuan, L, Ge, Y, Yin, FF, Lee, WR, and Wu, QJ. "Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: The benefits of DVH prediction." Journal of Applied Clinical Medical Physics 16.2 (January 1, 2015): 241-250.

Source

scopus

Published In

Journal of Applied Clinical Medical Physics

Volume

16

Issue

2

Publish Date

2015

Start Page

241

End Page

250

DOI

10.1120/jacmp.v16i2.5204

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

Authors

Wu, QJ; Yuan, L; Li, T; Yin, F; Ge, Y

MLA Citation

Wu, QJ, Yuan, L, Li, T, Yin, F, and Ge, Y. "Knowledge modeling for computer aided treatment planning." January 1, 2015.

Source

scopus

Published In

Ifmbe Proceedings

Volume

51

Publish Date

2015

Start Page

425

End Page

427

DOI

10.1007/978-3-319-19387-8_103

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

Authors

Yuan, L; Ge, Y; Sheng, Y; Yin, F; Wu, QJ

MLA Citation

Yuan, L, Ge, Y, Sheng, Y, Yin, F, and Wu, QJ. "Knowledge based automatic beam angle determination for lung IMRT planning." January 1, 2015.

Source

scopus

Published In

Ifmbe Proceedings

Volume

51

Publish Date

2015

Start Page

440

End Page

443

DOI

10.1007/978-3-319-19387-8_107

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

Authors

Yuan, L; Ge, Y; Yin, F; Wu, QJ

MLA Citation

Yuan, L, Ge, Y, Yin, F, and Wu, QJ. "A rapid learning approach for the knowledge modeling of radiation therapy plan." January 1, 2015.

Source

scopus

Published In

Ifmbe Proceedings

Volume

51

Publish Date

2015

Start Page

1492

End Page

1494

DOI

10.1007/978-3-319-19387-8_362

© 2015 SPIE. Infrared imaging fault detection which is treated as an ideal, non-contact, non-destructive testing method is applied to the circuit board fault detection. Since Infrared images obtained by handheld infrared camera with wide-Angle lens have both rigid and non-rigid deformations. To solve this problem, a new demons algorithm based on regional information entropy was proposed. The new method overcame the shortcomings of traditional demons algorithm that was sensitive to the intensity. First, the information entropy image was gotten by computing regional information entropy of the image. Then, the deformation between the two images was calculated that was the same as demons algorithm. Experimental results demonstrated that the proposed algorithm has better robustness in intensity inconsistent images registration compared with the traditional demons algorithm. Achieving accurate registration between intensity inconsistent infrared images provided strong support for the temperature contrast..

Authors

Lu, C; Ma, L; Yu, M; Cui, S; Wu, Q

MLA Citation

Lu, C, Ma, L, Yu, M, Cui, S, and Wu, Q. "Infrared image non-rigid registration based on regional information entropy demons algorithm." January 1, 2015.

Source

scopus

Published In

Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics

Volume

9449

Publish Date

2015

DOI

10.1117/12.2075406

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

Authors

Li, T; Wu, Q; Yang, Y; Rodrigues, A; Yin, F-F; Jackie Wu, Q

MLA Citation

Li, T, Wu, Q, Yang, Y, Rodrigues, A, Yin, F-F, and Jackie Wu, Q. "Quality assurance for online adapted treatment plans: benchmarking and delivery monitoring simulation." Medical Physics 42.1 (January 2015): 381-390.

PMID

25563278

Source

epmc

Published In

Medical Physics

Volume

42

Issue

1

Publish Date

2015

Start Page

381

End Page

390

DOI

10.1118/1.4904021

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

Authors

Yuan, L; Wu, QJ; Yin, F-F; Jiang, Y; Yoo, D; Ge, Y

MLA Citation

Yuan, L, Wu, QJ, Yin, F-F, Jiang, Y, Yoo, D, and Ge, Y. "Incorporating single-side sparing in models for predicting parotid dose sparing in head and neck IMRT." Medical physics 41.2 (February 2014): 021728-.

PMID

24506619

Source

epmc

Published In

Medical Physics

Volume

41

Issue

2

Publish Date

2014

Start Page

021728

DOI

10.1118/1.4862075

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

Authors

Qiu, J-J; Chang, Z; Horton, JK; Wu, Q-RJ; Yoo, S; Yin, F-F

MLA Citation

Qiu, J-J, Chang, Z, Horton, JK, Wu, Q-RJ, Yoo, S, and Yin, F-F. "Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)." Medical dosimetry : official journal of the American Association of Medical Dosimetrists 39.2 (January 27, 2014): 152-158.

PMID

24480375

Source

epmc

Published In

Medical Dosimetry

Volume

39

Issue

2

Publish Date

2014

Start Page

152

End Page

158

DOI

10.1016/j.meddos.2013.12.001

The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies including gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V10) or 20Gy (V20) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V5 and D5). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung. In terms of MU and delivery time, V-MAT is significantly more efficient for APBI than for conventional 3D-CRT and static-beam IMRT. © 2014 American Association of Medical Dosimetrists.

Authors

Qiu, JJ; Chang, Z; Horton, JK; Wu, QRJ; Yoo, S; Yin, FF

MLA Citation

Qiu, JJ, Chang, Z, Horton, JK, Wu, QRJ, Yoo, S, and Yin, FF. "Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)." Medical Dosimetry 39.2 (January 1, 2014): 152-158.

Source

scopus

Published In

Medical Dosimetry

Volume

39

Issue

2

Publish Date

2014

Start Page

152

End Page

158

DOI

10.1016/j.meddos.2013.12.001

To build a statistical model to quantitatively correlate the anatomic features of structures and the corresponding dose-volume histogram (DVH) of head and neck (HN) Tomotherapy (Tomo) plans. To study if the model built upon one intensity modulated radiation therapy (IMRT) technique (such as conventional Linac) can be used to predict anticipated organs-at-risk (OAR) DVH of patients treated with a different IMRT technique (such as Tomo). To study if the model built upon the clinical experience of one institution can be used to aid IMRT planning for another institution.Forty-four Tomotherapy intensity modulate radiotherapy plans of HN cases (Tomo-IMRT) from Institution A were included in the study. A different patient group of 53 HN fixed gantry IMRT (FG-IMRT) plans was selected from Institution B. The analyzed OARs included the parotid, larynx, spinal cord, brainstem, and submandibular gland. Two major groups of anatomical features were considered: the volumetric information and the spatial information. The volume information includes the volume of target, OAR, and overlapped volume between target and OAR. The spatial information of OARs relative to PTVs was represented by the distance-to-target histogram (DTH). Important anatomical and dosimetric features were extracted from DTH and DVH by principal component analysis. Two regression models, one for Tomotherapy plan and one for IMRT plan, were built independently. The accuracy of intratreatment-modality model prediction was validated by a leave one out cross-validation method. The intertechnique and interinstitution validations were performed by using the FG-IMRT model to predict the OAR dosimetry of Tomo-IMRT plans. The dosimetry of OARs, under the same and different institutional preferences, was analyzed to examine the correlation between the model prediction and planning protocol.Significant patient anatomical factors contributing to OAR dose sparing in HN Tomotherapy plans have been analyzed and identified. For all the OARs, the discrepancies of dose indices between the model predicted values and the actual plan values were within 2.1%. Similar results were obtained from the modeling of FG-IMRT plans. The parotid gland was spared in a comparable fashion during the treatment planning of two institutions. The model based on FG-IMRT plans was found to predict the median dose of the parotid of Tomotherapy plans quite well, with a mean error of 2.6%. Predictions from the FG-IMRT model suggested the median dose of the larynx, median dose of the brainstem and D2 of the brainstem could be reduced by 10.5%, 12.8%, and 20.4%, respectively, in the Tomo-IMRT plans. This was found to be correlated to the institutional differences in OAR constraint settings. Re-planning of six Tomotherapy patients confirmed the potential of optimization improvement predicted by the FG-IMRT model was correct.The authors established a mathematical model to correlate the anatomical features and dosimetric indexes of OARs of HN patients in Tomotherapy plans. The model can be used for the setup of patient-specific OAR dose sparing goals and quality control of planning results.The institutional clinical experience was incorporated into the model which allows the model from one institution to generate a reference plan for another institution, or another IMRT technique.

Authors

Lian, J; Yuan, L; Ge, Y; Chera, BS; Yoo, DP; Chang, S; Yin, F; Wu, QJ

MLA Citation

Lian, J, Yuan, L, Ge, Y, Chera, BS, Yoo, DP, Chang, S, Yin, F, and Wu, QJ. "Modeling the dosimetry of organ-at-risk in head and neck IMRT planning: an intertechnique and interinstitutional study." Medical Physics 40.12 (December 2013): 121704-null.

PMID

24320490

Source

epmc

Published In

Medical Physics

Volume

40

Issue

12

Publish Date

2013

Start Page

121704

DOI

10.1118/1.4828788

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

Authors

Li, T; Wu, Q; Zhang, Y; Vergalasova, I; Lee, WR; Yin, F-F; Wu, QJ

MLA Citation

Li, T, Wu, Q, Zhang, Y, Vergalasova, I, Lee, WR, Yin, F-F, and Wu, QJ. "Strategies for automatic online treatment plan reoptimization using clinical treatment planning system: a planning parameters study." Med Phys 40.11 (November 2013): 111711-.

PMID

24320419

Source

pubmed

Published In

Medical Physics

Volume

40

Issue

11

Publish Date

2013

Start Page

111711

DOI

10.1118/1.4823473

Authors

Yuan, L; Wu, Q; Jiang, Y; Li, T; Yin, F; David, Y; Ge, Y

MLA Citation

Yuan, L, Wu, Q, Jiang, Y, Li, T, Yin, F, David, Y, and Ge, Y. "Incorporating Trade-Off in Knowledge Modeling of Parotid Dose Sparing in Head and Neck IMRT." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S715

End Page

S715

DOI

10.1016/j.ijrobp.2013.06.1893

Authors

Pang, T; Yuan, L; Ge, Y; Jiang, Y; Das, S; Yoo, D; Yin, F; Wu, Q

MLA Citation

Pang, T, Yuan, L, Ge, Y, Jiang, Y, Das, S, Yoo, D, Yin, F, and Wu, Q. "Quality Evaluation of an Automatic VMAT Planning Method for Head-and-Neck Cancer Cases." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S581

End Page

S582

DOI

10.1016/j.ijrobp.2013.06.1542

Authors

Li, H; Bowsher, J; Jiang, Y; Pang, T; Wu, Q; Yan, S; Czito, B; Willett, C; Yin, F

MLA Citation

Li, H, Bowsher, J, Jiang, Y, Pang, T, Wu, Q, Yan, S, Czito, B, Willett, C, and Yin, F. "Effects of PET Reconstruction Parameters on Region-of-Interest Contouring by SUV Threshold." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S340

End Page

S340

DOI

10.1016/j.ijrobp.2013.06.895

Authors

Yuan, L; Lian, J; Chang, S; Wu, Q; Yin, F; Jiang, Y; Ge, Y

MLA Citation

Yuan, L, Lian, J, Chang, S, Wu, Q, Yin, F, Jiang, Y, and Ge, Y. "Modeling Organs at Risk Dose Sparing in Head and Neck Tomotherapy and IMRT Plans: A Comparison Study." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S624

End Page

S624

DOI

10.1016/j.ijrobp.2013.06.1649

Authors

Jiang, Y; Yuan, L; Wu, Q; Yin, F; Ge, Y

MLA Citation

Jiang, Y, Yuan, L, Wu, Q, Yin, F, and Ge, Y. "Normal Tissue Toxicity Criteria in Radiation Therapy." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S621

End Page

S622

DOI

10.1016/j.ijrobp.2013.06.1643

Authors

Yang, Y; Yuan, L; Li, T; Ge, Y; Yin, F; Lee, W; Wu, Q

MLA Citation

Yang, Y, Yuan, L, Li, T, Ge, Y, Yin, F, Lee, W, and Wu, Q. "Quantitative Comparison of Knowledge-Guided IMRT Planning to Expert Planning for Prostate Cancer." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S56

End Page

S56

DOI

10.1016/j.ijrobp.2013.06.145

Authors

Lian, J; Yuan, L; Ge, Y; Chera, B; Yoo, D; Chang, S; Yin, F; Wu, Q

MLA Citation

Lian, J, Yuan, L, Ge, Y, Chera, B, Yoo, D, Chang, S, Yin, F, and Wu, Q. "Intertechnique and Interinstitutional Modeling of the Dosimetry of Organs-at-Risk in Head and Neck IMRT Plans." October 1, 2013.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

87

Issue

2

Publish Date

2013

Start Page

S56

End Page

S56

DOI

10.1016/j.ijrobp.2013.06.146

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

Authors

Good, D; Lo, J; Lee, WR; Wu, QJ; Yin, F-F; Das, SK

MLA Citation

Good, D, Lo, J, Lee, WR, Wu, QJ, Yin, F-F, and Das, SK. "A knowledge-based approach to improving and homogenizing intensity modulated radiation therapy planning quality among treatment centers: an example application to prostate cancer planning." Int J Radiat Oncol Biol Phys 87.1 (September 1, 2013): 176-181.

PMID

23623460

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

87

Issue

1

Publish Date

2013

Start Page

176

End Page

181

DOI

10.1016/j.ijrobp.2013.03.015

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

Authors

Chang, Z; Wu, Q; Yan, H; Yang, Y; Giles, W; Busselberg, C; Lipscomb, R; Yin, F

MLA Citation

Chang, Z, Wu, Q, Yan, H, Yang, Y, Giles, W, Busselberg, C, Lipscomb, R, and Yin, F. "SU-E-T-143: Dosimetric Characteristics of TrueBeam STx System with High Definition Multi-Leaf Collimator: Commissioning of Stereotactic Radiosurgery." Medical physics 40.6Part12 (June 2013): 236-237.

PMID

28518977

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part12

Publish Date

2013

Start Page

236

End Page

237

DOI

10.1118/1.4814578

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

Authors

Liu, B; Adamson, J; Rodrigues, A; Zhou, F; Yin, F; Wu, Q

MLA Citation

Liu, B, Adamson, J, Rodrigues, A, Zhou, F, Yin, F, and Wu, Q. "WE-G-108-08: A Novel Technique for VMAT QA with EPID in Cine Mode On Varian TrueBeam." Medical Physics 40.6Part30 (June 2013): 502-null.

PMID

28519131

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part30

Publish Date

2013

Start Page

502

DOI

10.1118/1.4815632

Correct MLC modeling is essential to the accurate IMRT delivery. Most TPSs use simplified models with parameters of leaf transmission (LT) and dynamic leaf gap (DLG). The common way to determine them is through extrapolation from measurements. In this study, we propose a new technique to determine these parameters with EPID and ion chambers using specially designed fluence pattern.The fluence has symmetric twin peaks separated by 10cm and each has a width of 2cm. The DMLC files were generated based on initial values of LT and DLG from measurements. Plans were delivered to EPID and analyzed in portal dosimetry software. The FWHM of each peak was evaluated. The optimal DLG value was determined by iteratively adjusting its value and repeating calculation to match the FWHM between calculation and measurement. To determine LT, an ion chamber was placed at the central axis where dose is primarily from MLC leakage. Both Millennium MLC (MMLC) and HDMLC in Varian Truebeam were investigated for photon energies of 6X, 10X, 15X. QAs of realistic IMRT plans were performed and compared.The MMLC has measured LT values from 1.3%-1.5%, and corresponding optimal values 1.6-1.9%, an increase of 20% on average. The DLGs extrapolated from measurement are 0.8-0.9 mm, and optimal at 1.2-1.6 mm, a 60% increase. For HDMLC, the LTs are similar. However, the DLGs are much smaller, with extrapolations at 0.15-0.21 mm, and optimal at 0.4-0.7 mm. The portal dosimetry QA for 6X plan with MMLC reduces pixels failing γ (criteria: 3%/1mm) from 9% to 3% with optimal parameters. Similarly, QA for 15X plan with HDMLC reduces from 21% to 6%.We have developed a method to determine optimal MLC parameters that minimize TPS modeling errors. This ensures that patient specific QA reflects the true discrepancies in treatment plan or machine delivery.

Authors

Wu, Q; Chang, Z; Adamson, J; Ren, L; Yin, F

MLA Citation

Wu, Q, Chang, Z, Adamson, J, Ren, L, and Yin, F. "SU-E-T-560: A Method to Determine Optimal Dynamic MLC Parameters for Varian Truebeam with Millennium MLC and HDMLC." Medical Physics 40.6Part19 (June 2013): 334-null.

PMID

28524505

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part19

Publish Date

2013

Start Page

334

DOI

10.1118/1.4814989

Lateral dimensions of the incident electron beam (spot sizes) are essential for accurate modelling of x-ray fields, especially for small field output factors and penumbrae. We present spot sizes measured on the Varian TrueBeam linac and propose an explanation for the observed shapes.Spot were measured on 3 TrueBeam linacs using the 4X, 6X, 6FFF, 8X, 10X, 10FFF, and 15X beams. Two methods were used: a spot camera, and an edge CT reconstruction based on images of a thin plate with edge intersecting the beam at different collimator rotations. 2-dimensional Gaussian functions were fit to the data, with the spot orientation used as a fitting parameter.Spots were consistent for the 3 linacs. Sigmas of the fitted Gaussians were between 0.47 and 1.05 mm for all the beams. The 6X, 6FFF, and 15X beams had a distinct shape: the major axes were 30-40% larger than the minor axes, and the major axes were oriented 40 degrees from the inplane direction. The remaining spots were more symmetric, with major axes at most 15% larger than minor, and a similar orientation. The spot shapes could be explained by positing a helical electron motion at the entrance to the bend magnet, and using the known (non-achromatic) transport through the magnet. Fringe fields of the bend magnet, solenoid, or steering coils could produce the helical motion; the precise source is not known. Spots measured with the edge technique were 10% smaller in size than those measured with the camera. The 10FFF spots were 10% smaller than the 10X spots, as measured with the camera, but the 6X and 6FFF spots were similar to each other.Representative spots for TrueBeam are presented. Values may be used for input to modelling of fluence output, for example using Monte Carlo methods. Several of the authors are employees of Varian Medical Systems, as noted in the affiliations.

Authors

Sawkey, D; Constantin, M; Mansfield, S; Star-Lack, J; Rodrigues, A; Wu, Q; Svatos, M

MLA Citation

Sawkey, D, Constantin, M, Mansfield, S, Star-Lack, J, Rodrigues, A, Wu, Q, and Svatos, M. "SU-E-T-553: Measurement of Incident Electron Spots On TrueBeam." Medical physics 40.6Part19 (June 2013): 332-.

PMID

28524481

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part19

Publish Date

2013

Start Page

332

DOI

10.1118/1.4814982

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

Authors

Rodrigues, A; Yin, F; Wu, Q

MLA Citation

Rodrigues, A, Yin, F, and Wu, Q. "SU-E-T-602: Dynamic Electron Arc Radiotherapy (DEAR): A Planning Study." Medical physics 40.6Part20 (June 2013): 344-.

PMID

28519099

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part20

Publish Date

2013

Start Page

344

DOI

10.1118/1.4815030

Experience, knowledge, and guidelines about intensity modulated radiation therapy (IMRT) have been accumulated over the past decade, but they have largely not been formally extracted or modeled to support more efficient and optimal treatment planning. Therefore in routine clinic practice, IMRT/VMAT treatment planning for each individual case is still managed in a time-consuming iterative process, where planner and physician attempt to create the clinically optimal plan. Each patient presents a unique set of anatomic constraints on how much the dose can be "sculpted" to spare normal tissue, which is quantitatively unknown to the planner. Balancing the competing goals; i.e. target coverage and organs at risk (OARs) sparing, is a trial-and-error process guided largely by the planner's and physician's personal experience, skill, and knowledge. Further, for any given dose distribution, likely clinical outcomes (e.g. tumor control rate and normal tissue toxicity) are not readily apparent to physicians. The limited knowledge available in this area (e.g. QUANTEC guidelines, population-based data) is not integrated into treatment planning systems, and physicians are usually left to their intuition and experience. Thus, there is a strong need to explicitly organize, model and integrate the available knowledge from various sources into the planning process. In this session, we will present and discuss some of the early efforts in knowledge development, modeling, and application in treatment planning. These efforts are managed at different levels, from disease sites to institution. We will present clinical examples demonstrating how ready-access and integration of such knowledge into the planning process will improve the efficiency of IMRT/VMAT planning and the overall quality of resulting plans. We will also discuss the potentials and challenges to collaboratively extract, represent, integrate, and apply these various sources of knowledge in the radiation therapy via proper infrastructure management. Finally, we would also discuss the potential of such knowledge integration and sharing in helping small, independent clinics where physicians and physicists often provide services for a broad spectrum of disease sites, and where peer review with in depth specialty knowledge input can be limited.1. Extracting and organizing knowledge at different levels, by different disease site, and in institutional and multi-institutional settings 2. Infrastructure for collaborative knowledge building, modeling and sharing 3. Modeling and representation of knowledge for treatment planning, leading to cost and quality effective standardization of plan optimization Q-R Jackie Wu: Research grant from Varian Medical Systems and NIH; Ying Xiao: Research grants from NIH/ACR and Pennsylvania State Dept of Health; Charles Mayo: Research grant from Varian Medical Systems; Wilko Verbakel: The department of radiation oncology of VUmc has a research agreement with Varian Medical Systems. Verbakel and Dahele have received honorarium / travel expenses from Varian Medical Systems. Yaorong Ge: Research grant from NIH.

Authors

Mayo, C; Verbakel, W; Wu, Q; Xiao, Y; Ge, Y

MLA Citation

Mayo, C, Verbakel, W, Wu, Q, Xiao, Y, and Ge, Y. "TH-C-500-01: Collaborative Knowledge Modeling and Integration for Radiation Therapy Planning." Medical physics 40.6Part32 (June 2013): 535-.

PMID

28517892

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part32

Publish Date

2013

Start Page

535

DOI

10.1118/1.4815757

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

Authors

Sheng, Y; Li, T; Yuan, L; Yin, F; Wu, Q

MLA Citation

Sheng, Y, Li, T, Yuan, L, Yin, F, and Wu, Q. "TH-C-137-11: Dose-Guided Automatic IMRT Planning: A Feasibility Study." Medical physics 40.6Part32 (June 2013): 535-.

PMID

28517871

Source

epmc

Published In

Medical Physics

Volume

40

Issue

6Part32

Publish Date

2013

Start Page

535

DOI

10.1118/1.4815754

Authors

Li, T; Wu, QJ; Matzen, T; O' Daniel, J

MLA Citation

Li, T, Wu, QJ, Matzen, T, and O' Daniel, J. "TU-C-108-07: Transmission Detector Array System for RT Delivery Monitoring: Validation Testing." June 2013.

Source

crossref

Published In

Medical Physics

Volume

40

Issue

6Part26

Publish Date

2013

Start Page

431

End Page

432

DOI

10.1118/1.4815371

Authors

Lu, S; Yuan, L; Yin, F; Wu, QJ

MLA Citation

Lu, S, Yuan, L, Yin, F, and Wu, QJ. "SU-E-T-707: Evaluation of the Quality of Organs-At-Risk Dose Sparing in Anorectal and Prostate IMRT Plans." June 2013.

Source

crossref

Published In

Medical Physics

Volume

40

Issue

6Part22

Publish Date

2013

Start Page

369

End Page

369

DOI

10.1118/1.4815134

Authors

Yuan, L; Pang, T; Ge, Y; Li, T; Yin, F; Wu, QJ

MLA Citation

Yuan, L, Pang, T, Ge, Y, Li, T, Yin, F, and Wu, QJ. "TH-C-137-08: Dosimetric Quality of An Automatic IMRT Planning Method for Head and Neck Cancer Cases." June 2013.

Source

crossref

Published In

Medical Physics

Volume

40

Issue

6Part32

Publish Date

2013

Start Page

534

End Page

534

DOI

10.1118/1.4815751

Authors

Yuan, L; Pang, T; Ge, Y; Li, T; Jiang, Y; Yin, F; Wu, QJ

MLA Citation

Yuan, L, Pang, T, Ge, Y, Li, T, Jiang, Y, Yin, F, and Wu, QJ. "SU-E-CAMPUS-T-05: Quality Evaluation of An Automatic VMAT Planning Method for Head and Neck Cancer Cases." June 2013.

Source

crossref

Published In

Medical Physics

Volume

40

Issue

6Part22

Publish Date

2013

Start Page

380

End Page

380

DOI

10.1118/1.4815183

Authors

Rodrigues, A; Yin, F; Wu, Q

MLA Citation

Rodrigues, A, Yin, F, and Wu, Q. "TU-E-108-02: Dynamic Electron Arc Radiotherapy (DEAR): A Feasibility Study." June 2013.

Source

crossref

Published In

Medical Physics

Volume

40

Issue

6Part26

Publish Date

2013

Start Page

443

End Page

443

DOI

10.1118/1.4815417

BACKGROUND AND PURPOSE: To report single institution's IGRT and dosimetry analysis on the 37 Gy/5 fraction prostate SBRT clinical trial. MATERIALS/METHODS: The IRB (Duke University Medical Center) approved clinical trial has treated 28 patients with stage T1-T2c prostate cancer with a regimen of 37 Gy in 5 fractions using IMRT and IGRT protocols since 2009. The clinical trial protocol requires CT/MRI imaging for the prostate delineation; a margin of 3 mm in posterior direction and 5 mm elsewhere for planning target volume (PTV); and strict dose constraints for primary organs-at-risks (OARs) including the bladder, the rectum, and the femoral heads. Rigid IGRT process is also an essential part of the protocol. Precise patient and prostate positioning and dynamic tracking of prostate motion are performed with electromagnetic localization device (Calypso) and on-board imaging (OBI) system. Initial patient and target alignment is performed based on fiducials with OBI imaging system and Calypso system. Prior to treatment, cone-beam CT (CBCT) is performed for soft tissue alignment verification. During treatment, per-beam corrections for target motion using translational couch movements is performed before irradiating each field, based on electromagnetic localization or on-board imaging localization. Dosimetric analysis on target coverage and OAR sparing is performed based on key DVH parameters corresponding to protocol guidance. IGRT analysis is focused on the average frequency and magnitude of corrections during treatment, and overall intra-fractional target drift. A margin value is derived using actual target motion data and the margin recipe from Van Herk et al., and is compared to the current one in practice. In addition, cumulative doses with and without per-beam IGRT corrections are compared to assess the benefit of online IGRT. RESULTS: 1. No deviation has been found in 10 of 14 dosimetric constraints, with minor deviations in the rest 4 constraints.2. Online IGRT techniques including Calypso, OBI and CBCT supplement each other to create an effective and reliable system on tracking target and correcting intra-fractional motion.3. On average ½ corrections have been performed per fraction, with magnitude of (0.22 ± 0.11) cm. Average target drift magnitude is (0.7 ± 1.3) mm in one direction during each fraction.4. Benefit from per-beam correction in overall review is small: most differences from no correction are < 0.1 Gy for PTV D1cc/Dmean and < 1%/1.5 cc for OAR parameters. Up to 1.5 Gy reduction was seen in PTV D99% without online correction. Largest differences for OARs are -4.1 cc and +1.6 cc in the V50% for the bladder and the rectum, respectively. However, online IGRT helps to catch unexpected significant target motion.5. Margin derived from actual target motion is 2.5 mm isotropic, consist with current practice. CONCLUSIONS: Clinical experience of the 37 Gy/5-fraction prostate SBRT from a single institution is reported. Dosimetric analysis demonstrated excellent target coverage and OAR sparing for our first 28 patients in this trial. Online IGRT techniques implemented are both effective and reliable. Per-beam correction in general provides a small benefit in dosimetry. Target motion measured by online localization devices confirms that current margin selection is adequate.

Authors

Wu, QJ; Li, T; Yuan, L; Yin, F-F; Lee, WR

MLA Citation

Wu, QJ, Li, T, Yuan, L, Yin, F-F, and Lee, WR. "Single institution's dosimetry and IGRT analysis of prostate SBRT." Radiation Oncology (London, England) 8 (January 2013): 215-null.

PMID

24034234

Source

epmc

Published In

Radiation Oncology

Volume

8

Publish Date

2013

Start Page

215

DOI

10.1186/1748-717X-8-215

Authors

Li, T; Wu, Q; Yuan, L; Yin, F; Lee, W

MLA Citation

Li, T, Wu, Q, Yuan, L, Yin, F, and Lee, W. "Prostate SBRT in 5 Fractions: Initial Report on Dosimetric Results and IGRT Experiences." November 1, 2012.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

84

Issue

3

Publish Date

2012

Start Page

S815

End Page

S815

DOI

10.1016/j.ijrobp.2012.07.2180

Authors

Wu, Q; Yuan, L; Li, T; Kirkpatrick, J; Yin, F; Ge, Y

MLA Citation

Wu, Q, Yuan, L, Li, T, Kirkpatrick, J, Yin, F, and Ge, Y. "Knowledge-based Organ-at-Risk Sparing Models and Individualized Trade-offs in Intensity Modulated Radiation Therapy Planning." November 1, 2012.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

84

Issue

3

Publish Date

2012

Start Page

S27

End Page

S27

DOI

10.1016/j.ijrobp.2012.07.075

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

Authors

Yuan, L; Ge, Y; Lee, WR; Yin, FF; Kirkpatrick, JP; Wu, QJ

MLA Citation

Yuan, L, Ge, Y, Lee, WR, Yin, FF, Kirkpatrick, JP, and Wu, QJ. "Quantitative analysis of the factors which affect the interpatient organ-at-risk dose sparing variation in IMRT plans." Medical Physics 39.11 (November 2012): 6868-6878.

PMID

23127079

Source

epmc

Published In

Medical Physics

Volume

39

Issue

11

Publish Date

2012

Start Page

6868

End Page

6878

DOI

10.1118/1.4757927

A TrueBeam linear accelerator (TB-LINAC) is designed to deliver standard flattened and flattening-filter-free (FFF) beams. In our institute, three TB-LINAC units are installed. In this work, composite data of the three units and multi-unit comparison are presented.Each TB-LINAC can deliver photon beams from 4MV to 15MV, electron beams from 6MeV to 22MeV, and 6MV-FFF and 10MV-FFF. Dosimetric characteristics are systematically measured for commissioning including percent depth dose (PDD), beam profile, relative scatter factor, dynamic leaf shift, output factor and MLC leakage. Critic considerations of Pion of FFF photon beams and dosimetric penumbra are investigated.All measured PDDs and profiles of photon and electron matched well across the three machines. Beam data were quantitatively compared and combined through average to yield composite beam data. The discrepancies among the machines were quantified using standard deviation (SD). For example, the mean SD of the PDDs among the three units is 0.12%, and the mean SD of the profiles is 0.40% for 10MV-FFF open fields. The variations of Pion of the chamber CC13 is 1.2±0.1% under 6MV-FFF and 2.0±0.5% from dmax to the 18cm-off-axis point at 35cm depth under 40×40cm2 . The measured relative output factors range from 0.866 to 1.141 with the mean discrepancy of 0.06±0.04% among the three units. The measured wedge factors range from 0.863 to 1.254 with the mean overall discrepancy of 0.04±0.04%. The mean MLC transmission and dynamic leaf shift were measured from 1.0% to 1.5% and from 0.77mm to 0.96 mm from 4MV to 15MV. The mean penumbra of various photon beams are measured from 5.88±0.09mm to 5.99±0.13mm from 4MV to 15MV at 10cm depth of 10×10 cm2 .Dosimetric data demonstrated that the three units could and had been matched well. The systematically measured data might be useful for future reference.

Authors

Chang, Z; Wu, Q; Adamson, J; Ren, L; Bowsher, J; Yan, H; Thomas, A; Yin, F

MLA Citation

Chang, Z, Wu, Q, Adamson, J, Ren, L, Bowsher, J, Yan, H, Thomas, A, and Yin, F. "SU-E-T-104: Commissioning and Dosimetric Characteristics of TrueBeam System: Composite Data of Three TrueBeam Machines." Medical Physics 39.6Part11 (June 2012): 3726-null.

PMID

28517167

Source

epmc

Published In

Medical Physics

Volume

39

Issue

6Part11

Publish Date

2012

Start Page

3726

DOI

10.1118/1.4735162

To study prostate-bed motion after prostatectomy using the surgical clips as a surrogate.On the treatment planning CT, surgical clips within the PTV are identified and contoured. They are also identified and contoured in each daily CBCT. The center of mass (COM) coordinates for each clip within the native reference frame of each image set of CT and CBCT are recorded. Each CBCT (for daily image guidance) is registered to the planning CT based on the pelvic bony structure. The resulted 3D transformation matrix is used to convert the clip coordinates in the CBCT to the planning CT reference frame. Difference between the converted COM coordinates and the one in planning CT is taken as the rigid motion of the prostate bed relative to the pelvic bony structure during the course of radiation therapy. The motion data are then analyzed using statistical error analysis and quantified by the commonly defined M (average over all fractions and all patients), S (stdev of averages per patient, the systematic motion), and s (root mean square of stdev per patient, the random motion). Among a large pool of patients, seven patients were selected for this retrospective study, each with 3 to 11 identifiable clips and 17 to 26 CBCT sets. The total number of clips is 44 and total daily CBCT sets 160.In the (right-left, anterio-posterior, foot-head) directions, the M values are (0.2 mm, 0.4 mm, -0.6 mm), S (0.2, 2.5, 3.2), and s (1.7, 2.6, 2.1).Relative to the bony pelvic structure, the prostate bed motion characteristics are similar to that of intact prostate, as summarized in Table 2 of Rasch et al 2005 ('Target Definition in Prostate, Head, and Neck.' Semin Radiat Oncol 15:136-145).

Authors

Song, H; Salama, J; Yoo, D; Oleson, J; Wu, Q

MLA Citation

Song, H, Salama, J, Yoo, D, Oleson, J, and Wu, Q. "SU-E-J-23: Prostate Bed Motion Study Using Surgical Clips Based on Daily CBCT." Medical physics 39.6Part6 (June 2012): 3657-.

PMID

28517607

Source

epmc

Published In

Medical Physics

Volume

39

Issue

6Part6

Publish Date

2012

Start Page

3657

DOI

10.1118/1.4734856

To report the inter-fractional prostate bed motion (PBM) during post-prostatectomy radiotherapy using cone-beam CT (CBCT). The correlations between PBM, anterior rectal wall and posterior bladder wall shifts were also investigated.Seventy CBCT and 8 planning CT scans from 8 patients treated with prostate bed radiotherapy were retrospectively analyzed. For each CBCT-CT pair, two rigid image registrations were performed: one based on surgical clips and the other based on pelvic bony anatomy. Each registration gives a displacement vector. The difference between the two registration displacements represents the PBM. In addition, rectum/bladder contours on CT and CBCT scans were compared to identify the organ wall motion. Shifts of the anterior rectal wall and posterior bladder wall were assessed by averaging the slice-by-slice distances between contours on two image sets, measured along an anterior-posterior line passing through the symphysis pubis.The prostate bed motion in the left-right (LR), anterior-posterior (AP) and superior-inferior (SI) directions was (0.1±0.9)mm, (0.9±1.6)mm, and (-0.4±1.9)mm, respectively. The derived PTV-CTV margin for LR, AP and SI motion was 3mm, 5mm, and 6mm, respectively. Pearson's correlation coefficients between PBM and anterior rectal wall (whole length) shifts, PBM and the cranial half of anterior rectal wall shifts, and PBM and posterior bladder wall shifts, were 0.43, 0.47, and 0.67, respectively.The magnitude of PBM relative to pelvic bony anatomy in all three directions was small. The correlation between average anterior rectal wall shifts and PBM was weak-to-moderate, which may be due to rectum contouring inconsistency. Possible sources for this inconsistency include: non-uniform rectal wall motion through its length, low CBCT image contrast, and artifacts due to filling. Significant correlation between average posterior bladder wall shifts and PBM suggests bladder wall motion may also be a suitable surrogate for PBM in the AP direction.

Authors

Xu, Z; Li, T; Lee, W; Hood, R; Godfrey, D; Wu, Q

MLA Citation

Xu, Z, Li, T, Lee, W, Hood, R, Godfrey, D, and Wu, Q. "SU-E-J-16: Prostate Bed Motion during Post-Prostatectomy Radiotherapy." Medical physics 39.6Part6 (June 2012): 3655-.

PMID

28517611

Source

epmc

Published In

Medical Physics

Volume

39

Issue

6Part6

Publish Date

2012

Start Page

3655

DOI

10.1118/1.4734849

To implement a quality assurance (QA) system for the treatment delivery of online adaptive radiation therapy utilizing Dynamic Machine Information (DMI).DMI provides the expected/actual MLC leaf-positions, delivered MU, and beam-on status every 50ms during delivery. In this study a stream of DMI inputs is simulated by playing back Dynalog information recorded while delivering a test fluence map (FM). Based on these DMI inputs, the QA system performs three levels of monitoring/verification on the plan delivery process: (1) Following each input, actual and expected FMs delivered up to the current MLC position is dynamically updated using corresponding MLC positions in the DMI. The magnitude and frequency of pixel-by-pixel fluence differences between these two FMs are calculated and visualized in histograms.(2) At each control point, actual MLC positions are verified against the treatment plan for potential errors in data transfer between the treatment planning system (TPS) and the MLC controller.(3) Both (1) and (2) can signal beam-hold with a user-specified error tolerance.(4) After treatment, delivered dose is reconstructed in TPS based on DMI data during delivery, and compared to planned dose.(1) Efficiency: Average latency from DMI input to the completion of fluence difference calculation is <1ms.(2) Efficacy: For test FM, transient error in leaf positions is (-0.07±0.28)mm; cumulative errors in delivered fluence is (0.003±0.183)% of the maximal fluence. The system can also identify data transfer errors between TPS and MLC controller. Off-line dose reconstruction and evaluation show <0.5% dosimetric discrepancy from planned dose distribution for the test FM.This QA system is capable of identifying MLC position/fluence errors in near real-time, and assessing dosimetric impact of the treatment delivery process. It is thus a valuable tool for clinical implementation of online adaptive radiation therapy. (Research partially supported by Varian) Research partially supported by Varian Medical Systems.

Authors

Li, T; Yuan, L; Wu, Q; Yin, F; Wu, QJ

MLA Citation

Li, T, Yuan, L, Wu, Q, Yin, F, and Wu, QJ. "MO-D-BRB-09: Treatment Delivery QA for Online Adaptive Radiation Therapy Based on Dynamic Machine Information (DMI): A Feasibility Study." Medical physics 39.6Part21 (June 2012): 3867-3868.

PMID

28518229

Source

epmc

Published In

Medical Physics

Volume

39

Issue

6Part21

Publish Date

2012

Start Page

3867

End Page

3868

DOI

10.1118/1.4735790

To investigate th applicability of the flattening filter free (FFF) to fractionated radiotherapy of head and neck cancer.Twelve patients previously treated with IMRT were selected. A SIB protocol was chosen so that 66/54 Gy were prescribed to the gross tumors/elective nodal volumes in 30 fractions. Photon beams of 6X(6X-FFF) were used for both IMRT (@ 9 gantry angles) and VMAT (single and dual full arcs). Consistent optimization and acceptance criteria were used for all plans, with prescription dose to cover 90% of PTV66 and hot spots limited to 110% and within PTV66. Both plan quality and deliver-ability were compared.All plans met clinical objectives. The IMRT plan quality is similar or slightly better than VMAT, except that PTV66 conformity index is significantly better in 2-arc VMAT (1.18) than IMRT (1.32). The total MUs for IMRT are 1680/2090 for 6X/6X-FFF, a 24% increase. However, the total beam-on time (BOT) under treatment automation is 430/400 seconds for 6X(@300 MU/min)/6X-FFF (@400 MU/min), a 6% decrease. Increasing dose rate to the maximum (600/1400 for 6X and 6X-FFF) can reduce BOT by up to 50%, but at a cost of increased MU (up to 40%) and degraded plan quality. Significant reduction in MU and BOT are realized in VMAT, with ∼600 MU for both 6X and 6X-FFF and either single or dual-arcs. The BOT for VMAT is governed by the gantry speed and approximately 1 min for single arc and 2 min for dual arcs.Plan quality is similar between IMRT and 2-arc VMAT for both 6X and 6X-FFF. Total MU for IMRT and delivery time is significantly higher for IMRT than VMAT, but not much different between flat and non-flat beams. For standard fractionated radiotherapy of HN cancer, there is no advantage for the non-flat beam. The recommended choice is 2-arc VMAT.

Authors

Wu, Q; Yoo, S; Das, S; Yin, F

MLA Citation

Wu, Q, Yoo, S, Das, S, and Yin, F. "SU-E-T-559: Evaluation of Flatening Filter Free (FFF) Beams in Radiotherapy of Head and Neck Cancer." Medical physics 39.6Part19 (June 2012): 3834-.

PMID

28517087

Source

epmc

Published In

Medical Physics

Volume

39

Issue

6Part19

Publish Date

2012

Start Page

3834

DOI

10.1118/1.4735648

Authors

Chang, Z; Wu, Q; Adamson, J; Ren, L; Bowsher, J; Yan, H; Thomas, A; Yin, F

MLA Citation

Chang, Z, Wu, Q, Adamson, J, Ren, L, Bowsher, J, Yan, H, Thomas, A, and Yin, F. "SU-E-T-74: Assessing Effects of Ion Collection Efficiency in Flattening Filter-Free (FFF) Beams on Three TrueBeam Machines." June 2012.

Source

crossref

Published In

Medical Physics

Volume

39

Issue

6Part10

Publish Date

2012

Start Page

3719

End Page

3719

DOI

10.1118/1.4735130

Authors

Ashmeg, S; O'Daniel, J; Wu, Q; Yin, F

MLA Citation

Ashmeg, S, O'Daniel, J, Wu, Q, and Yin, F. "TH-E-BRB-11: Benchmarking Flattening-Filter Free Photons for IMRT/VMAT." June 2012.

Source

crossref

Published In

Medical Physics

Volume

39

Issue

6Part31

Publish Date

2012

Start Page

4011

End Page

4011

DOI

10.1118/1.4736361

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

Authors

Li, T; Yuan, L; Lee, W; Yin, F; Wu, QJ

MLA Citation

Li, T, Yuan, L, Lee, W, Yin, F, and Wu, QJ. "SU-E-T-406: Online Image-Guidance for Prostate SBRT: Dosimetric Benefits and Margin Analysis." June 2012.

PMID

28517233

Source

epmc

Published In

Medical Physics

Volume

39

Issue

6Part16

Publish Date

2012

Start Page

3798

DOI

10.1118/1.4735495

Authors

Li, T; Yuan, L; Wu, Q; Yin, F; Wu, QJ

MLA Citation

Li, T, Yuan, L, Wu, Q, Yin, F, and Wu, QJ. "Treatment Delivery QA for Online Adaptive Radiation Therapy Based On Dynamic Machine Information (DMI): A Feasibility Study." June 2012.

Source

wos-lite

Published In

Medical Physics

Volume

39

Issue

6

Publish Date

2012

Start Page

3867

End Page

3868

DOI

10.1118/1.4735790

Authors

Xu, Z; Li, T; Lee, W; Hood, R; Godfrey, D; Wu, Q

MLA Citation

Xu, Z, Li, T, Lee, W, Hood, R, Godfrey, D, and Wu, Q. "Prostate Bed Motion During Post-Prostatectomy Radiotherapy." June 2012.

Source

wos-lite

Published In

Medical Physics

Volume

39

Issue

6

Publish Date

2012

Start Page

3655

End Page

3655

DOI

10.1118/1.4734849

Authors

Yuan, L; Ge, Y; Li, T; Yin, F; Wu, QJ

MLA Citation

Yuan, L, Ge, Y, Li, T, Yin, F, and Wu, QJ. "Individualized Trade-Off of Dose Coverage and Sparing in IMRT Planning." June 2012.

PMID

28517546

Source

wos-lite

Published In

Medical Physics

Volume

39

Issue

6

Publish Date

2012

Start Page

3850

End Page

3850

DOI

10.1118/1.4735716

Authors

Yuan, L; Ge, Y; Li, T; Yin, F; Wu, QJ

MLA Citation

Yuan, L, Ge, Y, Li, T, Yin, F, and Wu, QJ. "Modeling Inter-Patient Variation of Organ-At-Risk Sparing in IMRT Plans: An Evidence-Based Plan Quality Evaluation." June 2012.

PMID

28518274

Source

wos-lite

Published In

Medical Physics

Volume

39

Issue

6

Publish Date

2012

Start Page

3868

End Page

3868

DOI

10.1118/1.4735791

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

Authors

O'Daniel, J; Das, S; Wu, QJ; Yin, F-F

MLA Citation

O'Daniel, J, Das, S, Wu, QJ, and Yin, F-F. "Volumetric-modulated arc therapy: effective and efficient end-to-end patient-specific quality assurance." Int J Radiat Oncol Biol Phys 82.5 (April 1, 2012): 1567-1574.

PMID

21470797

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

82

Issue

5

Publish Date

2012

Start Page

1567

End Page

1574

DOI

10.1016/j.ijrobp.2011.01.018

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

Authors

Ren, L; Chetty, IJ; Zhang, J; Jin, J-Y; Wu, QJ; Yan, H; Brizel, DM; Lee, WR; Movsas, B; Yin, F-F

MLA Citation

Ren, L, Chetty, IJ, Zhang, J, Jin, J-Y, Wu, QJ, Yan, H, Brizel, DM, Lee, WR, Movsas, B, and Yin, F-F. "Development and clinical evaluation of a three-dimensional cone-beam computed tomography estimation method using a deformation field map." Int J Radiat Oncol Biol Phys 82.5 (April 1, 2012): 1584-1593.

PMID

21477945

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

82

Issue

5

Publish Date

2012

Start Page

1584

End Page

1593

DOI

10.1016/j.ijrobp.2011.02.002

The risk of sterility in males undergoing radiotherapy in the pelvic region indicates the use of a shielding device, which offers protection to the testes for patients wishing to maintain fertility. The use of such devices in the realm of intensity-modulated radiotherapy (IMRT) in the pelvic region can pose many obstacles during simulation, treatment planning, and delivery of radiotherapy. This work focuses on the development and execution of an IMRT plan for the treatment of anal cancer using a scrotal shielding device on a clinical patient. An IMRT plan was developed using Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA), using a wide array of gantry angles as well as fixed jaw and fluence editing techniques. When possible, the entire target volume was encompassed by the treatment field. When the beam was incident on the scrotal shield, the jaw was fixed to avoid the device and the collimator rotation optimized to irradiate as much of the target as possible. This technique maximizes genital sparing and allows minimal irradiation of the gonads. When this fixed-jaw technique was found to compromise adequate coverage of the target, manual fluence editing techniques were used to avoid the shielding device. Special procedures for simulation, imaging, and treatment verification were also developed. In vivo dosimetry was used to verify and ensure acceptable dose to the gonads. The combination of these techniques resulted in a highly conformal plan that spares organs and risk and avoids the genitals as well as entrance of primary radiation onto the shielding device.

Authors

Hood, RC; Wu, QJ; McMahon, R; Czito, B; Willett, C

MLA Citation

Hood, RC, Wu, QJ, McMahon, R, Czito, B, and Willett, C. "IMRT treatment of anal cancer with a scrotal shield." Med Dosim 37.4 (2012): 432-435.

PMID

22538113

Source

pubmed

Published In

Medical Dosimetry

Volume

37

Issue

4

Publish Date

2012

Start Page

432

End Page

435

DOI

10.1016/j.meddos.2012.03.007

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

Authors

Wu, QJ; Thongphiew, D; Wang, Z; Willett, C; Marks, L; Yin, F-F

MLA Citation

Wu, QJ, Thongphiew, D, Wang, Z, Willett, C, Marks, L, and Yin, F-F. "Development of a 4D dosimetry simulation system in radiotherapy." International Journal of Biomedical Engineering and Technology 8.2-3 (2012): 230-244.

Source

scival

Published In

International Journal of Biomedical Engineering and Technology

Volume

8

Issue

2-3

Publish Date

2012

Start Page

230

End Page

244

DOI

10.1504/IJBET.2012.046088

Authors

Adamson, J; Wu, Q

MLA Citation

Adamson, J, and Wu, Q. "WE-E-BRB-07: EPID Based Verification of Delivered Fluence for VMAT with High Angular Resolution." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part32

Publish Date

2011

Start Page

3817

End Page

3817

DOI

10.1118/1.3613374

Authors

Galvin, J; Yin, F; Wu, Q; Xiao, Y

MLA Citation

Galvin, J, Yin, F, Wu, Q, and Xiao, Y. "WE-E-301-01: Practical Tips for VMAT Implementation." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part33

Publish Date

2011

Start Page

3823

End Page

3823

DOI

10.1118/1.3613395

Authors

Wu, Q; McMahon, R; Hood, R; Willett, C; Czito, B

MLA Citation

Wu, Q, McMahon, R, Hood, R, Willett, C, and Czito, B. "SU-E-T-419: Clinical Protocol for the Use of Scrotal Shields in IMRT Treatment of Anal Cancer." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part17

Publish Date

2011

Start Page

3584

End Page

3584

DOI

10.1118/1.3612373

Authors

Maurer, J; Godfrey, D; Wu, Q

MLA Citation

Maurer, J, Godfrey, D, and Wu, Q. "MO-D-BRC-07: Reducing Artifacts in Cone-Beam CT Images Caused by the Presence of An Array Used for Tracking Transponders during Radiotherapy." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part26

Publish Date

2011

Start Page

3713

End Page

3713

DOI

10.1118/1.3612971

Authors

Ge, Y; Minta, T; Kirkpatrick, J; Yuan, L; Wu, Q

MLA Citation

Ge, Y, Minta, T, Kirkpatrick, J, Yuan, L, and Wu, Q. "SU-E-T-23: Ontological Representation of Radiation Treatment Guidelines." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part10

Publish Date

2011

Start Page

3490

End Page

3490

DOI

10.1118/1.3611973

Authors

Yin, F; Thomas, A; Yan, H; Vergalasova, I; Adamovics, J; Wu, Q; Oldham, M

MLA Citation

Yin, F, Thomas, A, Yan, H, Vergalasova, I, Adamovics, J, Wu, Q, and Oldham, M. "SU-E-T-99: A Patient Specific QA Protocol for Verification of 4D Dosimetry." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part11

Publish Date

2011

Start Page

3508

End Page

3508

DOI

10.1118/1.3612050

Authors

Liu, H; Wu, Q

MLA Citation

Liu, H, and Wu, Q. "SU-E-T-773: Dosimetric and Geometric Evaluation of a Hybrid Strategy of Online Image Guidance and Offline Adaptive Planning for Prostate Cancer Radiotherapy." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part23

Publish Date

2011

Start Page

3668

End Page

3669

DOI

10.1118/1.3612737

Authors

Wu, Q; Liu, H

MLA Citation

Wu, Q, and Liu, H. "SU-E-T-782: A Novel Geometric Index to Evaluate Image Guidance Strategies for Prostate Cancer Adaptive Radiotherapy." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part23

Publish Date

2011

Start Page

3671

End Page

3671

DOI

10.1118/1.3612746

Authors

Liu, H; Wu, Q

MLA Citation

Liu, H, and Wu, Q. "SU-E-T-270: A “Rolling Average” Adaptive Planning Technique to Compensate Target Volume Changes in Prostate Cancer Radiotherapy." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part14

Publish Date

2011

Start Page

3549

End Page

3549

DOI

10.1118/1.3612221

Authors

Li, T; Zhang, Y; Wu, Q; Yuan, L; Yin, F; Wu, Q

MLA Citation

Li, T, Zhang, Y, Wu, Q, Yuan, L, Yin, F, and Wu, Q. "SU-C-110-01: Strategies for Online Plan Re-Optimization: Objective Settings and Starting Stage." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part2

Publish Date

2011

Start Page

3374

End Page

3374

DOI

10.1118/1.3611485

Authors

Yuan, L; Ge, Y; Li, T; Zhu, X; Yin, F; Wu, Q

MLA Citation

Yuan, L, Ge, Y, Li, T, Zhu, X, Yin, F, and Wu, Q. "SU-E-T-854: Key Anatomical Factors Influencing OAR Dose-Volume Distribution in Prostate IMRT Plans." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part24

Publish Date

2011

Start Page

3688

End Page

3688

DOI

10.1118/1.3612818

Authors

Yuan, L; Ge, Y; Li, T; Zhu, X; Yin, F; Wu, Q

MLA Citation

Yuan, L, Ge, Y, Li, T, Zhu, X, Yin, F, and Wu, Q. "TH-E-BRB-05: Modeling the Correlation Between OAR Dose Sparing and Patientˈs Anatomy in Head and Neck IMRT." June 2011.

Source

crossref

Published In

Medical Physics

Volume

38

Issue

6Part35

Publish Date

2011

Start Page

3867

End Page

3867

DOI

10.1118/1.3613562

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

Authors

Wu, QJ; Li, T; Wu, Q; Yin, F-F

MLA Citation

Wu, QJ, Li, T, Wu, Q, and Yin, F-F. "Adaptive radiation therapy: technical components and clinical applications." Cancer Journal (Sudbury, Mass.) 17.3 (May 2011): 182-189. (Review)

PMID

21610472

Source

epmc

Published In

Cancer Journal (Sudbury, Mass.)

Volume

17

Issue

3

Publish Date

2011

Start Page

182

End Page

189

DOI

10.1097/ppo.0b013e31821da9d8

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

Authors

Li, T; Thongphiew, D; Zhu, X; Lee, WR; Vujaskovic, Z; Yin, F-F; Wu, QJ

MLA Citation

Li, T, Thongphiew, D, Zhu, X, Lee, WR, Vujaskovic, Z, Yin, F-F, and Wu, QJ. "Adaptive prostate IGRT combining online re-optimization and re-positioning: a feasibility study." Physics in Medicine and Biology 56.5 (March 2011): 1243-1258.

PMID

21285485

Source

epmc

Published In

Physics in Medicine and Biology

Volume

56

Issue

5

Publish Date

2011

Start Page

1243

End Page

1258

DOI

10.1088/0031-9155/56/5/002

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

Authors

Zhu, X; Ge, Y; Li, T; Thongphiew, D; Yin, F-F; Wu, QJ

MLA Citation

Zhu, X, Ge, Y, Li, T, Thongphiew, D, Yin, F-F, and Wu, QJ. "A planning quality evaluation tool for prostate adaptive IMRT based on machine learning." Medical Physics 38.2 (February 2011): 719-726.

PMID

21452709

Source

epmc

Published In

Medical Physics

Volume

38

Issue

2

Publish Date

2011

Start Page

719

End Page

726

DOI

10.1118/1.3539749

We present a technique for planning and verification of craniospinal treatment with the patient in the supine position. Treatment delivery and verification is streamlined through the use of modern imaging techniques. Treatments use two lateral brain fields abutted to a single or pair of posterior spine fields. Treatment delivery is simplified by aligning all isocenters in the anterior-posterior and lateral directions. Patient positioning is accomplished via on-board kV imaging. Verification of field shape and junctions is accomplished with BB placement and MV portal imaging. Daily treatment is simplified by using only longitundinal couch shifts, which are recorded in the patient chart and RV database. The technique is simple to implement in a clinic that is already using a similar beam arrangement with the patient prone. It requires no additional devices to be fabricated (for immobilization or QA), and it takes advantage of all the existing elements of a modern linac.

Authors

McMahon, RL; Larrier, NA; Wu, QJ

MLA Citation

McMahon, RL, Larrier, NA, and Wu, QJ. "An image-guided technique for planning and verification of supine craniospinal irradiation." Journal of Applied Clinical Medical Physics 12.2 (January 31, 2011): 3310-null.

PMID

21587173

Source

epmc

Published In

Journal of Applied Clinical Medical Physics

Volume

12

Issue

2

Publish Date

2011

Start Page

3310

DOI

10.1120/jacmp.v12i2.3310

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

Authors

Wu, QJ; Meyer, J; Fuller, J; Godfrey, D; Wang, Z; Zhang, J; Yin, F-F

MLA Citation

Wu, QJ, Meyer, J, Fuller, J, Godfrey, D, Wang, Z, Zhang, J, and Yin, F-F. "Digital tomosynthesis for respiratory gated liver treatment: clinical feasibility for daily image guidance." Int J Radiat Oncol Biol Phys 79.1 (January 1, 2011): 289-296.

PMID

20646848

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

79

Issue

1

Publish Date

2011

Start Page

289

End Page

296

DOI

10.1016/j.ijrobp.2010.01.047

We present a technique for planning and verification of craniospinal treatment with the patient in the supine position. Treatment delivery and verification is streamlined through the use of modern imaging techniques. Treatments use two lateral brain fields abutted to a single or pair of posterior spine fields. Treatment delivery is simplified by aligning all isocenters in the anterior-posterior and lateral directions. Patient positioning is accomplished via on-board kV imaging. Verification of field shape and junctions is accomplished with BB placement and MV portal imaging. Daily treatment is simplified by using only longitundinal couch shifts, which are recorded in the patient chart and RV database. The technique is simple to implement in a clinic that is already using a similar beam arrangement with the patient prone. It requires no additional devices to be fabricated (for immobilization or QA), and it takes advantage of all the existing elements of a modern linac.

Authors

McMahon, RL; Larrier, NA; Wu, QJ

MLA Citation

McMahon, RL, Larrier, NA, and Wu, QJ. "An image-guided technique for planning and verification of supine craniospinal irradiation." Journal of Applied Clinical Medical Physics 12.2 (2011): 184-190.

Source

scival

Published In

Journal of Applied Clinical Medical Physics

Volume

12

Issue

2

Publish Date

2011

Start Page

184

End Page

190

Authors

Zhu, X; Li, T; Yin, F-F; Wu, QJ; Ge, Y

MLA Citation

Zhu, X, Li, T, Yin, F-F, Wu, QJ, and Ge, Y. "Response to comment on: A planning quality evaluation tool for prostate adaptive IMRT based on machine learning' Med. Phys. 38, 719 (2011)." Medical Physics 38.5 (2011): 2821--.

Source

scival

Published In

Medical Physics

Volume

38

Issue

5

Publish Date

2011

Start Page

2821-

DOI

10.1118/1.3578613

PURPOSE: Intensity-modulated radiation therapy (IMRT) has the potential to reduce toxicities associated with chemoradiotherapy in the treatment of anal cancer. This study reports the results of using IMRT in the treatment of anal cancer. METHODS AND MATERIALS: Records of patients with anal malignancies treated with IMRT at Duke University were reviewed. Acute toxicity was graded using the NCI CTCAEv3.0 scale. Overall survival (OS), metastasis-free survival (MFS), local-regional control (LRC) and colostomy-free survival (CFS) were calculated using the Kaplan-Meier method. RESULTS: Forty-seven patients with anal malignancy (89% canal, 11% perianal skin) were treated with IMRT between August 2006 and September 2008. Median follow-up was 14 months (19 months for SCC patients). Median radiation dose was 54 Gy. Eight patients (18%) required treatment breaks lasting a median of 5 days (range, 2-7 days). Toxicity rates were as follows: Grade 4: leukopenia (7%), thrombocytopenia (2%); Grade 3: leukopenia (18%), diarrhea (9%), and anemia (4%); Grade 2: skin (93%), diarrhea (24%), and leukopenia (24%). The 2-year actuarial overall OS, MFS, LRC, and CFS rates were 85%, 78%, 90% and 82%, respectively. For SCC patients, the 2-year OS, MFS, LRC, and CFS rates were 100%, 100%, 95%, and 91%, respectively. CONCLUSIONS: IMRT-based chemoradiotherapy for anal cancer results in significant reductions in normal tissue dose and acute toxicities versus historic controls treated without IMRT, leading to reduced rates of toxicity-related treatment interruption. Early disease-related outcomes seem encouraging. IMRT is emerging as a standard therapy for anal cancer.

Authors

Pepek, JM; Willett, CG; Wu, QJ; Yoo, S; Clough, RW; Czito, BG

MLA Citation

Pepek, JM, Willett, CG, Wu, QJ, Yoo, S, Clough, RW, and Czito, BG. "Intensity-modulated radiation therapy for anal malignancies: a preliminary toxicity and disease outcomes analysis." International Journal of Radiation Oncology, Biology, Physics 78.5 (December 2010): 1413-1419.

PMID

20231064

Source

epmc

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

78

Issue

5

Publish Date

2010

Start Page

1413

End Page

1419

DOI

10.1016/j.ijrobp.2009.09.046

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

Authors

Qiu, J-J; Chang, Z; Wu, QJ; Yoo, S; Horton, J; Yin, F-F

MLA Citation

Qiu, J-J, Chang, Z, Wu, QJ, Yoo, S, Horton, J, and Yin, F-F. "Impact of volumetric modulated arc therapy technique on treatment with partial breast irradiation." Int J Radiat Oncol Biol Phys 78.1 (September 1, 2010): 288-296.

PMID

20444558

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

78

Issue

1

Publish Date

2010

Start Page

288

End Page

296

DOI

10.1016/j.ijrobp.2009.10.036

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

Authors

Zhu, X; Thongphiew, D; McMahon, R; Li, T; Chankong, V; Yin, F-F; Wu, QJ

MLA Citation

Zhu, X, Thongphiew, D, McMahon, R, Li, T, Chankong, V, Yin, F-F, and Wu, QJ. "Arc-modulated radiation therapy based on linear models." Phys Med Biol 55.13 (July 7, 2010): 3873-3883.

PMID

20571210

Source

pubmed

Published In

Physics in Medicine and Biology

Volume

55

Issue

13

Publish Date

2010

Start Page

3873

End Page

3883

DOI

10.1088/0031-9155/55/13/020

Authors

Yoo, S; Das, S; Wu, Q; Brizel, D; Yin, F

MLA Citation

Yoo, S, Das, S, Wu, Q, Brizel, D, and Yin, F. "SU-GG-T-136: Treatment Plans Comparison with Static-Gantry IMRT and RapidArcTM for Head-And-Neck Cancers Involving Cervical Lymph Nodes." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part17

Publish Date

2010

Start Page

3216

End Page

3216

DOI

10.1118/1.3468526

Authors

O'Daniel, J; Kishore, M; Das, S; Wu, Q; Yoo, S; Yin, F

MLA Citation

O'Daniel, J, Kishore, M, Das, S, Wu, Q, Yoo, S, and Yin, F. "SU-GG-T-225: Gantry-Angle Dependence of a 2D Ion Chamber Array for IMAT QA." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part19

Publish Date

2010

Start Page

3237

End Page

3237

DOI

10.1118/1.3468616

Authors

Wu, Q; Yin, F; McMahon, R; Zhu, X; Das, S

MLA Citation

Wu, Q, Yin, F, McMahon, R, Zhu, X, and Das, S. "SU-GG-T-137: Similarities between Static and Rotational Intensity Modulated Plans." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part17

Publish Date

2010

Start Page

3216

End Page

3216

DOI

10.1118/1.3468527

Authors

Yoo, S; O'Daniel, J; Horton, J; Wu, Q; Yin, F

MLA Citation

Yoo, S, O'Daniel, J, Horton, J, Wu, Q, and Yin, F. "SU-GG-T-583: Dosimetric Comparison of Anisotropic Analytical and Pencil Beam Convolution Algorithms in Breast Cancer Radiation Treatment Planning." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part25

Publish Date

2010

Start Page

3321

End Page

3321

DOI

10.1118/1.3468984

Authors

Zhu, X; Thongphiew, D; McMahon, R; Li, T; Chankong, V; Yin, F; Wu, Q

MLA Citation

Zhu, X, Thongphiew, D, McMahon, R, Li, T, Chankong, V, Yin, F, and Wu, Q. "SU-EE-A1-03: Arc Modulated Radiation Therapy Based on Linear Models." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part25

Publish Date

2010

Start Page

3094

End Page

3095

DOI

10.1118/1.3468008

Authors

Li, T; Thongphiew, D; Zhu, X; Yin, F; Wu, Q

MLA Citation

Li, T, Thongphiew, D, Zhu, X, Yin, F, and Wu, Q. "WE-B-BRA-03: Adaptive Image-Guided Radiation Therapy (AIGRT) for Hypo-Fractionated Prostate Cancer Treatment." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part27

Publish Date

2010

Start Page

3414

End Page

3415

DOI

10.1118/1.3469343

Authors

Zhu, X; Li, T; Thongphiew, D; Ge, Y; Yin, F; Wu, Q

MLA Citation

Zhu, X, Li, T, Thongphiew, D, Ge, Y, Yin, F, and Wu, Q. "TU-E-BRB-03: A Planning Quality Evaluation Tool for Adaptive IMRT Treatment Based on Machine Learning." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part27

Publish Date

2010

Start Page

3400

End Page

3400

DOI

10.1118/1.3469286

Authors

Zhuang, T; Wu, Q

MLA Citation

Zhuang, T, and Wu, Q. "TU-B-BRA-01: Total Body Irradiation (TBI): Looking from Differrent Angles." June 2010.

Source

crossref

Published In

Medical Physics

Volume

37

Issue

6Part26

Publish Date

2010

Start Page

3375

End Page

3375

DOI

10.1118/1.3469185

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

Authors

Yoo, S; Wu, QJ; Lee, WR; Yin, F-F

MLA Citation

Yoo, S, Wu, QJ, Lee, WR, and Yin, F-F. "Radiotherapy treatment plans with RapidArc for prostate cancer involving seminal vesicles and lymph nodes." Int J Radiat Oncol Biol Phys 76.3 (March 1, 2010): 935-942.

PMID

20044214

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

76

Issue

3

Publish Date

2010

Start Page

935

End Page

942

DOI

10.1016/j.ijrobp.2009.07.1677

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

Authors

Wu, QJ; Yin, F-F; McMahon, R; Zhu, X; Das, SK

MLA Citation

Wu, QJ, Yin, F-F, McMahon, R, Zhu, X, and Das, SK. "Similarities between static and rotational intensity-modulated plans." Phys Med Biol 55.1 (January 7, 2010): 33-43.

PMID

19949257

Source

pubmed

Published In

Physics in Medicine and Biology

Volume

55

Issue

1

Publish Date

2010

Start Page

33

End Page

43

DOI

10.1088/0031-9155/55/1/003

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

Authors

Li, T; Zhu, X; Thongphiew, D; Lee, WR; Vujaskovic, Z; Wu, Q; Yin, F-F; Wu, QJ

MLA Citation

Li, T, Zhu, X, Thongphiew, D, Lee, WR, Vujaskovic, Z, Wu, Q, Yin, F-F, and Wu, QJ. "On-line adaptive radiation therapy: feasibility and clinical study." J Oncol 2010 (2010): 407236-.

PMID

21113304

Source

pubmed

Published In

Journal of Oncology

Volume

2010

Publish Date

2010

Start Page

407236

DOI

10.1155/2010/407236

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

Authors

O'Daniel, J; Das, S; Wu, J; Yin, F-F

MLA Citation

O'Daniel, J, Das, S, Wu, J, and Yin, F-F. "Patient specific quality assurance: Transition from IMRT to IMAT." Journal of Physics: Conference Series 250 (2010): 231-234.

Source

scival

Published In

Journal of Physics: Conference Series

Volume

250

Publish Date

2010

Start Page

231

End Page

234

DOI

10.1088/1742-6596/250/1/012050

Authors

Chang, Z; Wang, Z; Ma, J; Wu, Q; Kirkpatrick, J; Yin, F

MLA Citation

Chang, Z, Wang, Z, Ma, J, Wu, Q, Kirkpatrick, J, and Yin, F. "Cone-Beam CT 6 Degree-of-Freedom Image-Guidance for Intracranial Frameless Stereotactic RadioSurgery using 6D Robotic Couch." 2010.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

78

Issue

3

Publish Date

2010

Start Page

S280

End Page

S280

DOI

10.1016/j.ijrobp.2010.07.667

Authors

O'Daniel, JC; Das, S; Wu, Q; Yin, F

MLA Citation

O'Daniel, JC, Das, S, Wu, Q, and Yin, F. "Intensity Modulated Arc Therapy: Effective and Efficient End-to-end Patient Specific Quality Assurance." 2010.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

78

Issue

3

Publish Date

2010

Start Page

S763

End Page

S763

DOI

10.1016/j.ijrobp.2010.07.1766

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

Authors

Wu, QJ; Yoo, S; Kirkpatrick, JP; Thongphiew, D; Yin, F-F

MLA Citation

Wu, QJ, Yoo, S, Kirkpatrick, JP, Thongphiew, D, and Yin, F-F. "Volumetric arc intensity-modulated therapy for spine body radiotherapy: comparison with static intensity-modulated treatment." Int J Radiat Oncol Biol Phys 75.5 (December 1, 2009): 1596-1604.

PMID

19733447

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

75

Issue

5

Publish Date

2009

Start Page

1596

End Page

1604

DOI

10.1016/j.ijrobp.2009.05.005

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

Authors

Ma, J; Chang, Z; Wang, Z; Jackie Wu, Q; Kirkpatrick, JP; Yin, F-F

MLA Citation

Ma, J, Chang, Z, Wang, Z, Jackie Wu, Q, Kirkpatrick, JP, and Yin, F-F. "ExacTrac X-ray 6 degree-of-freedom image-guidance for intracranial non-invasive stereotactic radiotherapy: comparison with kilo-voltage cone-beam CT." Radiother Oncol 93.3 (December 2009): 602-608.

PMID

19846229

Source

pubmed

Published In

Radiotherapy and Oncology

Volume

93

Issue

3

Publish Date

2009

Start Page

602

End Page

608

DOI

10.1016/j.radonc.2009.09.009

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

Authors

Zhu, X; Bourland, JD; Yuan, Y; Zhuang, T; O'Daniel, J; Thongphiew, D; Wu, QJ; Das, SK; Yoo, S; Yin, FF

MLA Citation

Zhu, X, Bourland, JD, Yuan, Y, Zhuang, T, O'Daniel, J, Thongphiew, D, Wu, QJ, Das, SK, Yoo, S, and Yin, FF. "Tradeoffs of integrating real-time tracking into IGRT for prostate cancer treatment." Physics in Medicine and Biology 54.17 (September 2009): N393-N401.

PMID

19661570

Source

epmc

Published In

Physics in Medicine and Biology

Volume

54

Issue

17

Publish Date

2009

Start Page

N393

End Page

N401

DOI

10.1088/0031-9155/54/17/n03

Authors

Chang, Z; Wang, Z; Wu, Q; Bowsher, J; Yoo, S; Yin, F

MLA Citation

Chang, Z, Wang, Z, Wu, Q, Bowsher, J, Yoo, S, and Yin, F. "SU-FF-T-309: Quality Assurance for Imaging Guided Stereotactic RadioSurgery with Novalis Tx™ System." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part13

Publish Date

2009

Start Page

2592

End Page

2592

DOI

10.1118/1.3181789

Authors

Yoo, S; Das, S; Wu, Q; Brizel, D; Yoo, D; Yin, F

MLA Citation

Yoo, S, Das, S, Wu, Q, Brizel, D, Yoo, D, and Yin, F. "SU-FF-T-130: Radiotherapy Treatment Plans with RapidArc for Head-And-Neck Cancer." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part10

Publish Date

2009

Start Page

2549

End Page

2550

DOI

10.1118/1.3181604

Authors

Chang, Z; Wang, Z; Wu, Q; Kirkpatrick, J; Yin, F

MLA Citation

Chang, Z, Wang, Z, Wu, Q, Kirkpatrick, J, and Yin, F. "SU-EE-A3-02: Imaging Guided Frameless Stereotactic RadioSurgery Using CBCT 6D Image Registration and 6D Couch On Novalis Tx™ System." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part2

Publish Date

2009

Start Page

2430

End Page

2431

DOI

10.1118/1.3181106

Authors

Wang, Z; Kirkpatrick, J; Wu, Q; Chang, Z; Willett, C; Yin, F

MLA Citation

Wang, Z, Kirkpatrick, J, Wu, Q, Chang, Z, Willett, C, and Yin, F. "SU-FF-T-548: Comparison of Cone-Beam CT and Frame-Based Localizations for Stereotactic Radiosurgery with Fixed Head Rings and Removable Frames." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part17

Publish Date

2009

Start Page

2650

End Page

2650

DOI

10.1118/1.3182046

Authors

Wu, Q; McMahon, R; Chang, Z; Zhuang, T; O'Daniel, J; Yoo, S; Zhu, X; Yin, F

MLA Citation

Wu, Q, McMahon, R, Chang, Z, Zhuang, T, O'Daniel, J, Yoo, S, Zhu, X, and Yin, F. "SU-FF-T-301: Clinical Implementation and Commission of Volumetric Modulated Arc Therapy." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part13

Publish Date

2009

Start Page

2590

End Page

2590

DOI

10.1118/1.3181779

Authors

O'Daniel, J; McMahon, R; Chang, Z; Yan, H; Sakhalkar, H; Das, S; Wu, Q; Yin, F

MLA Citation

O'Daniel, J, McMahon, R, Chang, Z, Yan, H, Sakhalkar, H, Das, S, Wu, Q, and Yin, F. "SU-FF-T-314: Patient-Specific Quality Assurance Techniques for RapidArc Radiotherapy." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part13

Publish Date

2009

Start Page

2593

End Page

2594

DOI

10.1118/1.3181794

Authors

Zhu, X; Bourland, J; Yuan, Y; Zhuang, T; O'Daniel, J; Thongphiew, D; Wu, Q; Das, S; Yoo, S; Yin, F

MLA Citation

Zhu, X, Bourland, J, Yuan, Y, Zhuang, T, O'Daniel, J, Thongphiew, D, Wu, Q, Das, S, Yoo, S, and Yin, F. "SU-FF-J-56: Integrating Real-Time Tracking Into Image Guided Radiation Therapy for Prostate Cancer Treatment." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part6

Publish Date

2009

Start Page

2488

End Page

2488

DOI

10.1118/1.3181348

Authors

Yin, F; Wu, Q; Godfrey, D; Ren, L; Yoo, S; Maurer, J; Yan, H

MLA Citation

Yin, F, Wu, Q, Godfrey, D, Ren, L, Yoo, S, Maurer, J, and Yan, H. "TH-A-211A-01: Digital Tomosynthesis for Target Localization." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part26

Publish Date

2009

Start Page

2790

End Page

2791

DOI

10.1118/1.3182588

Authors

Wu, Q; Yoo, S; Kirkpatrick, J; McMahon, R; Thongphiew, D; Yin, F

MLA Citation

Wu, Q, Yoo, S, Kirkpatrick, J, McMahon, R, Thongphiew, D, and Yin, F. "SU-FF-T-567: Volumetric Modulated Arc Therapy for Spine Body Radiotherapy: Comparison with Static Intensity Modulated Treatment." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part18

Publish Date

2009

Start Page

2655

End Page

2655

DOI

10.1118/1.3182065

Authors

O'Daniel, J; Wu, Q; McMahon, R; Maurer, J; Lee, W; Yin, F

MLA Citation

O'Daniel, J, Wu, Q, McMahon, R, Maurer, J, Lee, W, and Yin, F. "SU-FF-J-55: Acceptance Testing and Quality-Assurance Protocols for the Calypso® 4D Localization System™ and Q-Fix®/Calypso® Couchtop." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part6

Publish Date

2009

Start Page

2488

End Page

2488

DOI

10.1118/1.3181347

Authors

Wu, Q; Lei, Y

MLA Citation

Wu, Q, and Lei, Y. "SU-FF-J-105: Is Offline Adaptive Planning Necessary for Online Image-Guided Radiotherapy of Prostate Cancer?." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part7

Publish Date

2009

Start Page

2500

End Page

2500

DOI

10.1118/1.3181397

Authors

Thongphiew, D; Zhu, X; Wu, Q; Wu, Q; Yin, F

MLA Citation

Thongphiew, D, Zhu, X, Wu, Q, Wu, Q, and Yin, F. "SU-FF-T-80: Hybrid Image Guided Radiation Therapy for Hypofractionated Prostate IMRT: Feasibility Study." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part9

Publish Date

2009

Start Page

2537

End Page

2538

DOI

10.1118/1.3181553

Authors

Yoo, S; Wu, Q; Lee, W; Yin, F

MLA Citation

Yoo, S, Wu, Q, Lee, W, and Yin, F. "SU-FF-T-574: Radiotherapy Treatment Plans with RapidArc for Prostate Cancer Involving Seminal Vesicles." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part18

Publish Date

2009

Start Page

2656

End Page

2656

DOI

10.1118/1.3182072

Authors

Lei, Y; Wu, Q

MLA Citation

Lei, Y, and Wu, Q. "MO-D-BRB-08: A Hybrid Strategy of Offline Adaptive Planning and Online Image Guidance for Prostate Cancer Radiotherapy." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part20

Publish Date

2009

Start Page

2694

End Page

2694

DOI

10.1118/1.3182218

Authors

Worthy, D; Wu, Q

MLA Citation

Worthy, D, and Wu, Q. "SU-FF-J-95: Dosimetric Margin Assessment for Rigid Setup Error by CBCT for HN-IMRT." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part7

Publish Date

2009

Start Page

2498

End Page

2498

DOI

10.1118/1.3181387

Authors

Wu, Q; Worthy, D

MLA Citation

Wu, Q, and Worthy, D. "SU-FF-T-102: Is Average Fractional Dose Representative of Cumulative Dose for HN-IMRT?." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part10

Publish Date

2009

Start Page

2543

End Page

2543

DOI

10.1118/1.3181576

Authors

Luo, W; Yin, F; Wu, Q; Fan, J

MLA Citation

Luo, W, Yin, F, Wu, Q, and Fan, J. "SU-FF-T-223: A New IMRT/RapidArc QA Procedure Utilizing MLC Dynalog Files." June 2009.

Source

crossref

Published In

Medical Physics

Volume

36

Issue

6Part12

Publish Date

2009

Start Page

2572

End Page

2572

DOI

10.1118/1.3181699

This study compares three online image guidance techniques (IGRT) for prostate IMRT treatment: bony-anatomy matching, soft-tissue matching, and online replanning. Six prostate IMRT patients were studied. Five daily CBCT scans from the first week were acquired for each patient to provide representative "snapshots" of anatomical variations during the course of treatment. Initial IMRT plans were designed for each patient with seven coplanar 15 MV beams on a Eclipse treatment planning system. Two plans were created, one with a PTV margin of 10 mm and another with a 5 mm PTV margin. Based on these plans, the delivered dose distributions to each CBCT anatomy was evaluated to compare bony-anatomy matching, soft-tissue matching, and online replanning. Matching based on bony anatomy was evaluated using the 10 mm PTV margin ("bone10"). Soft-tissue matching was evaluated using both the 10 mm ("soft10") and 5 mm ("soft5") PTV margins. Online reoptimization was evaluated using the 5 mm PTV margin ("adapt"). The replanning process utilized the original dose distribution as the basis and linear goal programming techniques for reoptimization. The reoptimized plans were finished in less than 2 min for all cases. Using each IGRT technique, the delivered dose distribution was evaluated on all 30 CBCT scans (6 patients x 5 CBCT/patient). The mean minimum dose (in percentage of prescription dose) to the CTV over five treatment fractions were in the ranges of 99%-100% (SD = 0.1%-0.8%), 65%-98% (SD = 0.4%-19.5%), 87%-99% (SD = 0.7%-23.3%), and 95%-99% (SD = 0.4%-10.4%) for the adapt, bone10, soft5, and soft10 techniques, respectively. Compared to patient position correction techniques, the online reoptimization technique also showed improvement in OAR sparing when organ motion/deformations were large. For bladder, the adapt technique had the best (minimum) D90, D50, and D30 values for 24, 17, and 15 fractions out of 30 total fractions, while it also had the best D90, D50, and D30 values for the rectum for 25, 16, and 19 fractions, respectively. For cases where the adapt plans did not score the best for OAR sparing, the gains of the OAR sparing in the repositioning-based plans were accompanied by an underdosage in the target volume. To further evaluate the fast online replanning technique, a gold-standard plan ("new" plan) was generated for each CBCT anatomy on the Eclipse treatment planning system. The OAR sparing from the online replanning technique was compared to the new plan. The differences in D90, D50, and D30 of the OARs between the adapt and the new plans were less than 5% in 3 patients and were between 5% and 10% for the remaining three. In summary, all IGRT techniques could be sufficient to correct simple geometrical variations. However, when a high degree of deformation or differential organ position displacement occurs, the online reoptimization technique is feasible with less than 2 min optimization time and provides improvements in both CTV coverage and OAR sparing over the position correction techniques. For these cases, the reoptimization technique can be a highly valuable online IGRT tool to correct daily treatment uncertainties, especially when hypofractionation scheme is applied and daily correction, rather than averaging over many fractions, is required to match the original plan.

Authors

Thongphiew, D; Wu, QJ; Lee, WR; Chankong, V; Yoo, S; McMahon, R; Yin, F-F

MLA Citation

Thongphiew, D, Wu, QJ, Lee, WR, Chankong, V, Yoo, S, McMahon, R, and Yin, F-F. "Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction." Medical Physics 36.5 (May 2009): 1651-1662.

PMID

19544782

Source

epmc

Published In

Medical Physics

Volume

36

Issue

5

Publish Date

2009

Start Page

1651

End Page

1662

DOI

10.1118/1.3095767

PURPOSE: To describe our experience and clinical strategy for stereotactic body radiotherapy (SBRT) of spinal lesions. METHODS AND MATERIALS: Thirty-two patients with 33 spinal lesions underwent computed tomography-based simulation while free breathing. Gross/clinical target volumes included involved portions of the vertebral body and paravertebral/epidural tumor. Planning target volume (PTV) expansion was 6 mm axially and 3 mm radially; the cord was excluded from the PTV. Biologic equivalent dose was calculated using the linear quadratic model with alpha/beta = 3 Gy. Treatment was linear accelerator based with on-board imaging; dose was adjusted to maintain cord dose within tolerance. Survival, local control, pain, and neurologic status were monitored. RESULTS: Twenty-one patients are alive at 1 year (median survival, 14 months). Median follow-up is 6 months for all patients (7 months for survivors). Mean previous radiotherapy dose to 22 patients was 35 Gy, and median interval was 17 months. Renal (31%), breast, and lung (19% each) were the most common histologic sites. Three SBRT fractions (range, one to four fractions) of 7 Gy (range, 5-16 Gy) were delivered. Median cord and target biologic equivalent doses were 70 Gy(3) and 34.3 Gy(10), respectively. Thirteen patients reported complete and 17 patients reported partial pain relief at 1 month. There were four failures (mean, 5.8 months) with magnetic resonance imaging evidence of in-field progression. No dosimetric parameters predictive of failure were identified. No treatment-related toxicity was seen. CONCLUSIONS: Spinal SBRT is effective in the palliative/re-treatment setting. Volume expansion must ensure optimal PTV coverage while avoiding spinal cord toxicity. The long-term safety of spinal SBRT and the applicability of the linear-quadratic model in this setting remain to be determined, particularly the time-adjusted impact of prior radiotherapy.

Authors

Nelson, JW; Yoo, DS; Sampson, JH; Isaacs, RE; Larrier, NA; Marks, LB; Yin, F-F; Wu, QJ; Wang, Z; Kirkpatrick, JP

MLA Citation

Nelson, JW, Yoo, DS, Sampson, JH, Isaacs, RE, Larrier, NA, Marks, LB, Yin, F-F, Wu, QJ, Wang, Z, and Kirkpatrick, JP. "Stereotactic body radiotherapy for lesions of the spine and paraspinal regions." Int J Radiat Oncol Biol Phys 73.5 (April 1, 2009): 1369-1375.

PMID

19004569

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

73

Issue

5

Publish Date

2009

Start Page

1369

End Page

1375

DOI

10.1016/j.ijrobp.2008.06.1949

Precise positioning of source and dosimeters is essential in the experimental determination of dosimetric characteristics of brachytherapy sources. Various near-water equivalent solid phantoms have been used to achieve the necessary precision in the positioning. However, the uncertainties in their chemical compositions may lead to non-negligible uncertainties in the determined doses. It is proposed here that ice may be used as an alternative to the conventional solid phantoms, since its chemical composition is identical to water while the positioning advantage associated with solid phantoms is retained. In this work, the feasibility of using ice as a solid phantom for brachytherapy dosimetry is investigated. Ice-to-water conversion factors are calculated at distances of 0.2-10 cm from the source, for six high- and low-energy photon-emitting brachytherapy sources and mono-energetic photons between 10 keV to 2.0 MeV. Practical issues and challenges associated with measuring dose in an ice phantom are discussed.

Authors

Song, H; Chen, Z; Yue, N; Wu, Q; Yin, F-F

MLA Citation

Song, H, Chen, Z, Yue, N, Wu, Q, and Yin, F-F. "Ice as a water-equivalent solid medium for brachytherapy dosimetric measurements." Radiat Environ Biophys 48.2 (April 2009): 145-151.

PMID

19066926

Source

pubmed

Published In

Radiation and Environmental Biophysics

Volume

48

Issue

2

Publish Date

2009

Start Page

145

End Page

151

DOI

10.1007/s00411-008-0205-9

PURPOSE: To evaluate digital tomosynthesis (DTS) technology for daily positioning of patients receiving accelerated partial breast irradiation (APBI) and to compare the positioning accuracy of DTS to three-dimensional cone-beam computed tomography (CBCT). METHODS AND MATERIALS: Ten patients who underwent APBI were scanned daily with on-board CBCT. A subset of the CBCT projections was used to reconstruct a stack of DTS image slices. To optimize soft-tissue visibility, the DTS images were reconstructed in oblique directions so that the tumor bed, breast tissue, ribs, and lungs were well separated. Coronal and sagittal DTS images were also reconstructed. Translational shifts of DTS images were obtained on different days from the same patients and were compared with the translational shifts of corresponding CBCT images. Seventy-seven CBCT scans and 291 DTS scans were obtained from nine evaluable patients. RESULTS: Tumor beds were best visible in the oblique DTS scans. One-dimensional positioning differences between DTS and CBCT images were 0.8-1.7 mm for the six patients with clips present and 1.2-2.0 mm for the three patients without clips. Because of the limited DTS scan angle, the DTS registration accuracy along the off-plane direction is lower than the accuracy along the in-plane directions. CONCLUSIONS: For patients receiving APBI, DTS localization offers comparable accuracy to CBCT localization for daily patient positioning while reducing mechanical constraints and imaging dose.

Authors

Zhang, J; Wu, QJ; Godfrey, DJ; Fatunase, T; Marks, LB; Yin, F-F

MLA Citation

Zhang, J, Wu, QJ, Godfrey, DJ, Fatunase, T, Marks, LB, and Yin, F-F. "Comparing digital tomosynthesis to cone-beam CT for position verification in patients undergoing partial breast irradiation." Int J Radiat Oncol Biol Phys 73.3 (March 1, 2009): 952-957.

PMID

19135316

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

73

Issue

3

Publish Date

2009

Start Page

952

End Page

957

DOI

10.1016/j.ijrobp.2008.10.036

PURPOSES: To quantitatively compare two-dimensional (2D) orthogonal kV with three-dimensional (3D) cone-beam CT (CBCT) for target localization; and to assess intrafraction motion with kV images in patients undergoing stereotactic body radiotherapy (SBRT). METHODS AND MATERIALS: A total of 50 patients with 58 lesions received 178 fractions of SBRT. After clinical setup using in-room lasers and skin/cradle marks placed at simulation, patients were imaged and repositioned according to orthogonal kV/MV registration of bony landmarks to digitally reconstructed radiographs from the planning CT. A subsequent CBCT was registered to the planning CT using soft tissue information, and the resultant "residual error" was measured and corrected before treatment. Posttreatment 2D kV and/or 3D CBCT images were compared with pretreatment images to determine any intrafractional position changes. Absolute averages, statistical means, standard deviations, and root mean square (RMS) values of observed setup error were calculated. RESULTS: After initial setup to external marks with laser guidance, 2D kV images revealed vector mean setup deviations of 0.67 cm (RMS). Cone-beam CT detected residual setup deviations of 0.41 cm (RMS). Posttreatment imaging demonstrated intrafractional variations of 0.15 cm (RMS). The individual shifts in three standard orthogonal planes showed no obvious directional biases. CONCLUSIONS: After localization based on superficial markings in patients undergoing SBRT, orthogonal kV imaging detects setup variations of approximately 3 to 4 mm in each direction. Cone-beam CT detects residual setup variations of approximately 2 to 3 mm.

Authors

Wang, Z; Nelson, JW; Yoo, S; Wu, QJ; Kirkpatrick, JP; Marks, LB; Yin, F-F

MLA Citation

Wang, Z, Nelson, JW, Yoo, S, Wu, QJ, Kirkpatrick, JP, Marks, LB, and Yin, F-F. "Refinement of treatment setup and target localization accuracy using three-dimensional cone-beam computed tomography for stereotactic body radiotherapy." International Journal of Radiation Oncology, Biology, Physics 73.2 (February 2009): 571-577.

PMID

19147021

Source

epmc

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

73

Issue

2

Publish Date

2009

Start Page

571

End Page

577

DOI

10.1016/j.ijrobp.2008.09.040

BACKGROUND: This study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5 mm) for three groups of tumors -- spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size and shape. METHODS: Fifteen cases (5 for each site) were studied retrospectively. All lesions either abutted or were an integral part of critical structures (brainstem, liver or spinal cord). For brain and liver lesions, treatment plans using a 3D-conformal static technique (3D), dynamic conformal arcs (DARC) or intensity modulation (IMRT) were designed with a conventional linear accelerator with standard 5 mm leaf width multi-leaf collimator, and a linear accelerator dedicated for radiosurgery and hypofractionated therapy with a 2.5 mm leaf width collimator. For the concave spine lesions, intensity modulation was required to provide adequate conformality; hence, only IMRT plans were evaluated using either the standard or small leaf-width collimators.A total of 70 treatment plans were generated and each plan was individually optimized according to the technique employed. The Generalized Estimating Equation (GEE) was used to separate the impact of treatment technique from the MLC system on plan outcome, and t-tests were performed to evaluate statistical differences in target coverage and organ sparing between plans. RESULTS: The lesions ranged in size from 2.6 to 12.5 cc, 17.5 to 153 cc, and 20.9 to 87.7 cc for the brain, liver, and spine groups, respectively. As a group, brain lesions were smaller than spine and liver lesions. While brain and liver lesions were primarily ellipsoidal, spine lesions were more complex in shape, as they were all concave. Therefore, the brain and the liver groups were compared for volume effect, and the liver and spine groups were compared for shape. For the brain and liver groups, both the radiosurgery MLC and the IMRT technique contributed to the dose sparing of organs-at-risk(OARs), as dose in the high-dose regions of these OARs was reduced up to 15%, compared to the non-IMRT techniques employing a 5 mm leaf-width collimator. Also, the dose reduction contributed by the fine leaf-width MLC decreased, as dose savings at all levels diminished from 4 - 11% for the brain group to 1 - 5% for the liver group, as the target structures decreased in volume. The fine leaf-width collimator significantly improved spinal cord sparing, with dose reductions of 14 - 19% in high to middle dose regions, compared to the 5 mm leaf width collimator. CONCLUSION: The fine leaf-width MLC in combination with the IMRT technique can yield dosimetric benefits in radiosurgery and hypofractionated radiotherapy. Treatment of small lesions in cases involving complex target/OAR geometry will especially benefit from use of a fine leaf-width MLC and the use of IMRT.

Authors

Wu, QJ; Wang, Z; Kirkpatrick, JP; Chang, Z; Meyer, JJ; Lu, M; Huntzinger, C; Yin, F-F

MLA Citation

Wu, QJ, Wang, Z, Kirkpatrick, JP, Chang, Z, Meyer, JJ, Lu, M, Huntzinger, C, and Yin, F-F. "Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions." Radiation Oncology (London, England) 4 (January 21, 2009): 3-null.

PMID

19159471

Source

epmc

Published In

Radiation Oncology

Volume

4

Publish Date

2009

Start Page

3

DOI

10.1186/1748-717X-4-3

PURPOSE: To evaluate on-board digital tomosynthesis (DTS) for patient positioning vs. two-dimensional (2D) radiography and three-dimensional cone beam (CBCT). METHODS AND MATERIALS: A total of 92 image sessions from 9 prostate cancer patients were analyzed. An on-board image set was registered to a corresponding reference image set. Four pairs of image sets were used: digitally reconstructed radiographs vs. on-board orthogonal paired radiographs for the 2D method, coronal-reference DTS vs. on-board coronal DTS for the coronal-DTS method, sagittal-reference DTS vs. on-board sagittal DTS for the sagittal-DTS method, and planning CT vs. CBCT for the CBCT method. The registration results were compared. RESULTS: The systematic errors in all methods were <1 mm/1 degrees . When registering the bony anatomy, the mean vector difference was 0.21 +/- 0.11 cm between 2D and CBCT, 0.11 +/- 0.08 cm between CBCT and coronal DTS, and 0.14 +/- 0.07 cm between CBCT and sagittal DTS. The correlation between CBCT to DTS was stronger (coefficient = 0.92-0.95) than the correlation between 2D and CBCT or DTS (coefficient = 0.81-0.83). When registering the soft tissue, the mean vector difference was 0.18 +/- 0.11 cm between CBCT and coronal DTS and 0.29 +/- 0.17 cm between CBCT and sagittal DTS. The correlation coefficient of CBCT to sagittal DTS and to coronal DTS was 0.84 and 0.92, respectively. CONCLUSION: DTS could provide equivalent results to CBCT when the bony anatomy is used as landmarks for prostate image-guided radiotherapy. For soft tissue-based positioning verification, coronal DTS produced equivalent results to CBCT, but sagittal DTS alone was insufficient. DTS could allow for comparable soft tissue-based target localization with faster scanning time and a lower imaging dose compared with CBCT.

Authors

Yoo, S; Wu, QJ; Godfrey, D; Yan, H; Ren, L; Das, S; Lee, WR; Yin, F-F

MLA Citation

Yoo, S, Wu, QJ, Godfrey, D, Yan, H, Ren, L, Das, S, Lee, WR, and Yin, F-F. "Clinical evaluation of positioning verification using digital tomosynthesis and bony anatomy and soft tissues for prostate image-guided radiotherapy." Int J Radiat Oncol Biol Phys 73.1 (January 1, 2009): 296-305.

PMID

19100923

Source

pubmed

Published In

Int J Radiat Oncol Biol Phys

Volume

73

Issue

1

Publish Date

2009

Start Page

296

End Page

305

DOI

10.1016/j.ijrobp.2008.09.006

BACKGROUND: This study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5 mm) for three groups of tumors -- spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size and shape. METHODS: Fifteen cases (5 for each site) were studied retrospectively. All lesions either abutted or were an integral part of critical structures (brainstem, liver or spinal cord). For brain and liver lesions, treatment plans using a 3D-conformal static technique (3D), dynamic conformal arcs (DARC) or intensity modulation (IMRT) were designed with a conventional linear accelerator with standard 5 mm leaf width multi-leaf collimator, and a linear accelerator dedicated for radiosurgery and hypofractionated therapy with a 2.5 mm leaf width collimator. For the concave spine lesions, intensity modulation was required to provide adequate conformality; hence, only IMRT plans were evaluated using either the standard or small leaf-width collimators.A total of 70 treatment plans were generated and each plan was individually optimized according to the technique employed. The Generalized Estimating Equation (GEE) was used to separate the impact of treatment technique from the MLC system on plan outcome, and t-tests were performed to evaluate statistical differences in target coverage and organ sparing between plans. RESULTS: The lesions ranged in size from 2.6 to 12.5 cc, 17.5 to 153 cc, and 20.9 to 87.7 cc for the brain, liver, and spine groups, respectively. As a group, brain lesions were smaller than spine and liver lesions. While brain and liver lesions were primarily ellipsoidal, spine lesions were more complex in shape, as they were all concave. Therefore, the brain and the liver groups were compared for volume effect, and the liver and spine groups were compared for shape. For the brain and liver groups, both the radiosurgery MLC and the IMRT technique contributed to the dose sparing of organs-at-risk(OARs), as dose in the high-dose regions of these OARs was reduced up to 15%, compared to the non-IMRT techniques employing a 5 mm leaf-width collimator. Also, the dose reduction contributed by the fine leaf-width MLC decreased, as dose savings at all levels diminished from 4 - 11% for the brain group to 1 - 5% for the liver group, as the target structures decreased in volume. The fine leaf-width collimator significantly improved spinal cord sparing, with dose reductions of 14 - 19% in high to middle dose regions, compared to the 5 mm leaf width collimator. CONCLUSION: The fine leaf-width MLC in combination with the IMRT technique can yield dosimetric benefits in radiosurgery and hypofractionated radiotherapy. Treatment of small lesions in cases involving complex target/OAR geometry will especially benefit from use of a fine leaf-width MLC and the use of IMRT.

Authors

Wu, QJ; Wang, Z; Kirkpatrick, JP; Chang, Z; Meyer, JJ; Lu, M; Huntzinger, C; Yin, F-F

MLA Citation

Wu, QJ, Wang, Z, Kirkpatrick, JP, Chang, Z, Meyer, JJ, Lu, M, Huntzinger, C, and Yin, F-F. "Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions." Radiation oncology (London, England) 4 (2009): 3--.

Source

scival

Published In

Radiation Oncology

Volume

4

Publish Date

2009

Start Page

3-

DOI

10.1186/1748-717X-4-3

Authors

Ren, L; Zhang, J; Thongphiew, D; Wu, Q; Yan, H; Brizel, DM; Lee, WR; Willett, CG; Yin, F

MLA Citation

Ren, L, Zhang, J, Thongphiew, D, Wu, Q, Yan, H, Brizel, DM, Lee, WR, Willett, CG, and Yin, F. "Development and Clinical Evaluation of a Novel 3D Digital Tomosynthesis (DTS) Reconstruction Method using a Deformation Field Map." 2009.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

75

Issue

3

Publish Date

2009

Start Page

S96

End Page

S96

DOI

10.1016/j.ijrobp.2009.07.236

Authors

Wang, Z; Kirkpatrick, JP; Wu, QJ; Chang, Z; Willett, CG; Yin, F

MLA Citation

Wang, Z, Kirkpatrick, JP, Wu, QJ, Chang, Z, Willett, CG, and Yin, F. "Imaging Guided Stereotactic Radiosurgery and its Accuracy Compared to Frame-based Localization." 2009.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

75

Issue

3

Publish Date

2009

Start Page

S690

End Page

S690

DOI

10.1016/j.ijrobp.2009.07.1573

Authors

Pepek, JM; Willett, CG; Clough, RW; Wu, QJ; Yoo, S; Czito, BG

MLA Citation

Pepek, JM, Willett, CG, Clough, RW, Wu, QJ, Yoo, S, and Czito, BG. "Intensity Modulated Radiation Therapy (IMRT) for Anal Cancer: The Duke University Experience." 2009.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

75

Issue

3

Publish Date

2009

Start Page

S267

End Page

S267

DOI

10.1016/j.ijrobp.2009.07.614

Authors

Thongphiew, D; Zhu, X; Wu, QJ; Lee, WR; Wu, Q; Chankong, V; Yin, F

MLA Citation

Thongphiew, D, Zhu, X, Wu, QJ, Lee, WR, Wu, Q, Chankong, V, and Yin, F. "Hybrid IGRT Technique for Prostate Hypofractionation." 2009.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

75

Issue

3

Publish Date

2009

Start Page

S648

End Page

S649

DOI

10.1016/j.ijrobp.2009.07.1479

Authors

Courlas, LD; O'Daniel, JC; Wu, QJ; Lee, W; Yin, F

MLA Citation

Courlas, LD, O'Daniel, JC, Wu, QJ, Lee, W, and Yin, F. "Calypso In Vivo Experience: Accuracy Compared to kV and CBCT Imaging and Analysis of Geometric Residual and Rotational Alignment." 2009.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

75

Issue

3

Publish Date

2009

Start Page

S584

End Page

S585

DOI

10.1016/j.ijrobp.2009.07.1335

Authors

Wu, Q; Kirkpatrick, J; Yon, S; McMahon, R; Thongphiew, D; Yin, F; Yin, F

MLA Citation

Wu, Q, Kirkpatrick, J, Yon, S, McMahon, R, Thongphiew, D, Yin, F, and Yin, F. "Comparing Static vs. Rotational IMRT for Spine Body Radiotherapy." 2009.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

75

Issue

3

Publish Date

2009

Start Page

S672

End Page

S672

DOI

10.1016/j.ijrobp.2009.07.1534

Real-time tracking can provide high accuracy localization for a moving target and minimize the effect of motion. Simultaneous kV-MV imaging has been proposed as a real-time tracking technique by utilizing the existing kV on-board imager (OBI) and the MV electronic portal device (EPID) mounted on the linear accelerator. The orthogonal pair of kV-MV images acquired simultaneously can provide 3-D localization in real-time. However, the kV and MV beams cross shooting the target interfere with each other with beam scattering, which affects the quality of images. The success of this modality heavily relies on the image quality, especially the visibility of the target, which was investigated in this study. The kV and MV images were acquired for a gold implant marker that was used as a surrogate of the target and placed in an IMRT thorax phantom, a dynamic phantom, and a pelvis phantom to test the image quality in different situations. Contrast-to-noise ration (CNR) was used to quantitatively describe the visibility of the target in the image. CNR can be obtained by statistical calculation from image processing and physics analysis with ion chamber measurement. The difference is described by contrast detection efficiency (CDE). By comparing the ratio (R) of CNR with and without the MV beam on, the MV beam scatter was found to have dramatically reduced the target visibility in the kV images (R=0.47), which was supported by an independent physics analysis that treats beam scatter as a noise. In contrast, the kV scatter effect on the MV images was minor (R=0.93). The effect of tumor motion was visible but tolerable for the target tracking purpose. CNR varied with different tumor sites and was lower for the pelvis than the thorax. Different kV imaging parameters such as kVp, mAs, and exposure time ms were tested for different cases. Considering a threshold of 1.0 CNR as a measure for the target visibility, a range of CNR from 1.3 to 4.2 was reached with appropriate tuning of those imaging parameters. This study has shown that CNR is a key parameter that can be used for assessing the visibility of the target in digital imaging and the quality of kV/MV images. It has also been shown that reasonable target visibility can be obtained using simultaneous kV-MV imaging for real-time target tracking.

Authors

Luo, W; Yoo, S; Wu, QJ; Wang, Z; Yin, F-F

MLA Citation

Luo, W, Yoo, S, Wu, QJ, Wang, Z, and Yin, F-F. "Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging." Medical Physics 35.12 (December 2008): 5501-5509.

PMID

19175109

Source

epmc

Published In

Medical Physics

Volume

35

Issue

12

Publish Date

2008

Start Page

5501

End Page

5509

DOI

10.1118/1.3002313

A new Novalis Tx system equipped with a high definition multileaf collimator (HDMLC) recently became available to perform both image-guided radiosurgery and conventional radiotherapy. It is capable of delivering a highly conformal radiation dose with three energy modes: 6 MV photon energy, 15 MV photon energy, and 6 MV photon energy in a stereotactic radiosurgery mode with 1000 MU/min dose rate. Dosimetric characteristics of the new Novalis Tx treatment unit with the HDMLC are systematically measured for commissioning. A high resolution diode detector and miniion-chamber detector are used to measure dosimetric data for a range of field sizes from 4 x 4 mm to 400 x 400 mm. The commissioned Novalis Tx system has passed the RPC stereotactic radiosurgery head phantom irradiation test. The Novalis Tx system not only expands its capabilities with three energy modes, but also achieves better beam conformity and sharer beam penumbra with HDMLC. Since there is little beam data information available for the new Novalis Tx system, we present in this work the dosimetric data of the new modality for reference and comparison.

Authors

Chang, Z; Wang, Z; Wu, QJ; Yan, H; Bowsher, J; Zhang, J; Yin, F-F

MLA Citation

Chang, Z, Wang, Z, Wu, QJ, Yan, H, Bowsher, J, Zhang, J, and Yin, F-F. "Dosimetric characteristics of novalis Tx system with high definition multileaf collimator." Med Phys 35.10 (October 2008): 4460-4463.

PMID

18975693

Source

pubmed

Published In

Medical Physics

Volume

35

Issue

10

Publish Date

2008

Start Page

4460

End Page

4463

DOI

10.1118/1.2977668

Authors

Meyer, J; Wu, QJ; Sampson, J; Yin, F-F; Tucci, D; David, B; Zhiheng, W; Kirkpatrick, J

MLA Citation

Meyer, J, Wu, QJ, Sampson, J, Yin, F-F, Tucci, D, David, B, Zhiheng, W, and Kirkpatrick, J. "DOSIMETRIC AND RADIOBIOLOGICAL IMPACT OF A HIGH-DEFINITION MICROMULTILEAF COLLIMATOR ON RADIOSURGERY OF VESTIBULAR SCHWANNOMAS." October 2008.

Source

wos-lite

Published In

Neuro Oncology

Volume

10

Issue

5

Publish Date

2008

Start Page

890

End Page

890

We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous cone-beam CT (CBCT) or planning CT data are used as the prior information, and the new patient volume to be reconstructed is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient DTS volume is then obtained by deforming the prior patient CBCT or CT volume according to the solution to the deformation field. This method is novel because it is the first method to combine deformable registration with limited angle image reconstruction. The method was tested in 2D cases using simulated projections of a Shepp-Logan phantom, liver, and head-and-neck patient data. The accuracy of the reconstruction was evaluated by comparing both organ volume and pixel value differences between DTS and CBCT images. In the Shepp-Logan phantom study, the reconstructed pixel signal-to-noise ratio (PSNR) for the 60 degrees DTS image reached 34.3 dB. In the liver patient study, the relative error of the liver volume reconstructed using 60 degrees projections was 3.4%. The reconstructed PSNR for the 60 degrees DTS image reached 23.5 dB. In the head-and-neck patient study, the new method using 60 degrees projections was able to reconstruct the 8.1 degrees rotation of the bony structure with 0.0 degrees error. The reconstructed PSNR for the 60 degrees DTS image reached 24.2 dB. In summary, the new reconstruction method can optimally estimate the volumetric information in DTS images using 60 degrees projections. Preliminary validation of the algorithm showed that it is both technically and clinically feasible for image guidance in radiation therapy.

Authors

Ren, L; Zhang, J; Thongphiew, D; Godfrey, DJ; Wu, QJ; Zhou, S-M; Yin, F-F

MLA Citation

Ren, L, Zhang, J, Thongphiew, D, Godfrey, DJ, Wu, QJ, Zhou, S-M, and Yin, F-F. "A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map." Med Phys 35.7 (July 2008): 3110-3115. (Letter)

PMID

18697536

Source

pubmed

Published In

Medical Physics

Volume

35

Issue

7

Publish Date

2008

Start Page

3110

End Page

3115

DOI

10.1118/1.2940725

Authors

Wang, Z; Chang, Z; Wu, Q; Zhou, S; Huntzinger, C; Yin, F

MLA Citation

Wang, Z, Chang, Z, Wu, Q, Zhou, S, Huntzinger, C, and Yin, F. "SU-GG-T-446: Dosimetric Characteristics of High Definition Multi-Leaf Collimator." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part16

Publish Date

2008

Start Page

2827

End Page

2827

DOI

10.1118/1.2962194

Authors

Wang, Z; Wu, Q; Chang, Z; Kirkpatrick, J; Yin, F

MLA Citation

Wang, Z, Wu, Q, Chang, Z, Kirkpatrick, J, and Yin, F. "SU-GG-T-454: Localization Accuracy of Cone-Beam CT Guided Radiosurgery as Investigated Utilizing a Geometric Phantom." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part16

Publish Date

2008

Start Page

2829

End Page

2829

DOI

10.1118/1.2962202

Authors

Zhou, S; Das, S; Yin, F; Yoo, S; Lee, W; Yan, H; Wu, Q; Wang, Z; Marks, L

MLA Citation

Zhou, S, Das, S, Yin, F, Yoo, S, Lee, W, Yan, H, Wu, Q, Wang, Z, and Marks, L. "SU-GG-J-81: Efficacy of Patient Setup Correction Procedure in Prostate Radiotherapy." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part6

Publish Date

2008

Start Page

2697

End Page

2697

DOI

10.1118/1.2961631

Authors

Yoo, S; Wu, Q; Godfrey, D; Ren, L; Yin, F

MLA Citation

Yoo, S, Wu, Q, Godfrey, D, Ren, L, and Yin, F. "SU-GG-I-52: Conversion of On-Board Digital TomoSynthesis (DTS) to HU Values." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part3

Publish Date

2008

Start Page

2654

End Page

2654

DOI

10.1118/1.2961450

Authors

Ma, J; Wu, Q; Godfrey, D; Yan, H; Ren, L; Yin, F

MLA Citation

Ma, J, Wu, Q, Godfrey, D, Yan, H, Ren, L, and Yin, F. "SU-GG-I-53: The Impact of Scan Angles On the Visibility of Anatomy in On-Board Digital Tomosynthesis (DTS) Images for Head and Neck Cancer Patients: A Single-Observer Study." June 2008.

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crossref

Published In

Medical Physics

Volume

35

Issue

6Part3

Publish Date

2008

Start Page

2654

End Page

2654

DOI

10.1118/1.2961451

Authors

Wu, Q; Thongphiew, D; Wang, Z; Yin, F; Yoo, S; Lee, W

MLA Citation

Wu, Q, Thongphiew, D, Wang, Z, Yin, F, Yoo, S, and Lee, W. "SU-GG-T-53: Integrating An Online Adaptive IMRT Process to the Prostate IGRT." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part9

Publish Date

2008

Start Page

2738

End Page

2738

DOI

10.1118/1.2961803

Authors

Wu, Q; Wang, Z; Thongphiew, D; Yin, F; Lee, W

MLA Citation

Wu, Q, Wang, Z, Thongphiew, D, Yin, F, and Lee, W. "SU-GG-T-13: Fast Seed Localization On MR Images For Post-Prostate Implant Dosimetry." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part9

Publish Date

2008

Start Page

2729

End Page

2729

DOI

10.1118/1.2961763

Authors

Thongphiew, D; Wu, Q; Lee, W; Chankong, V; Yin, F

MLA Citation

Thongphiew, D, Wu, Q, Lee, W, Chankong, V, and Yin, F. "SU-GG-T-54: On-Line Adaptive IMRT for Prostate Cancer." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part9

Publish Date

2008

Start Page

2738

End Page

2738

DOI

10.1118/1.2961804

Authors

Yoo, S; Wu, Q; Yin, F

MLA Citation

Yoo, S, Wu, Q, and Yin, F. "SU-GG-J-47: Clinical Implementation of An Integrated System for Image-Guided Radiation Therapy (IGRT) and Adaptive Radiation Therapy (ART)." June 2008.

Source

crossref

Published In

Medical Physics

Volume

35

Issue

6Part6

Publish Date

2008

Start Page

2689

End Page

2689

DOI

10.1118/1.2961605

To accommodate the inter- and intra-fractional motion of internal organs in prostate cancer treatment, a large margin (5mm-25mm) has often to be considered during radiation therapy planning. Normally, the inter- fractional motion is more substantial than the intra-fractional counterpart. Therefore, the study of inter-fractional motion pattern is of special interest for adaptive radiation therapy. Existing methods on organ motion analysis mainly focus on the deviation of an organ's shape from its mean shape. The deviation information is helpful in choosing a statistically proper margin, hut is of limited use for plan adaptation. In this paper, we propose a new deformation analysis method that can be directly used for plan adaptation. First, deformation estimation is accomplished by a fast deformable registration method, which utilizes a contour based multi-grid strategy to register treatment: cone-beam CT (CBCT) images with planning CT images. Second, dominant deformation modes are extracted by a novel deformation analysis approach. To be specific, a cooperative principal component analysis (PCA) method is developed to analyze the deformation held in a. coarse-to-fine strategy. The deformation modes are initialized by applying PCA on the organs as a whole and refined by analyzing the individual organs subsequently. The experimental results; show that the organ motion can be well characterized by a lew dominant deformation modes. Based on the dominant modes, a corresponding set of dominant modal plans could be generated for further optimization. Ultimately, an adaptive plan for each treatment can be obtained on-line while the margin can be effectively reduced to minimize the unnecessary radiation dosage.

Authors

Wang, B; Xuan, J; Wu, JQ; Zhang, S; Wang, Y

MLA Citation

Wang, B, Xuan, J, Wu, JQ, Zhang, S, and Wang, Y. "Deformation estimation and analysis for adaptive radiation therapy." Progress in Biomedical Optics and Imaging Proceedings of Spie 6914 (May 19, 2008).

Source

scopus

Published In

Progress in Biomedical Optics and Imaging Proceedings of Spie

Volume

6914

Publish Date

2008

DOI

10.1117/12.773548

Stereotactic body radiation therapy (SBRT), which delivers a much higher fractional dose than conventional treatment in only a few fractions, is an effective treatment for liver metastases. For patients who are treated under free-breathing conditions, however, respiration-induced tumor motion in the liver is a concern. Limited clinical information is available related to the impact of tumor motion and treatment technique on the dosimetric consequences. This study evaluated the dosimetric deviations between planned and delivered SBRT dose in the presence of tumor motion for three delivery techniques: three-dimensional conformal static beams (3DCRT), dynamic conformal arc (DARC), and intensity-modulated radiation therapy (IMRT). Five cases treated with SBRT for liver metastases were included in the study, with tumor motions ranging from 0.5 to 1.75 cm. For each case, three different treatment plans were developed using 3DCRT, DARC, and IMRT. The gantry/multileaf collimator (MLC) motion in the DARC plans and the MLC motion in the IMRT plans were synchronized to the patient's respiratory motion. Retrospectively sorted four-dimensional computed tomography image sets were used to determine patient-organ motion and to calculate the dose delivered during each respiratory phase. Deformable registration, using thin-plate-spline models, was performed to encode the tumor motion and deformation and to register the dose-per-phase to the reference phase images. The different dose distributions resulting from the different delivery techniques and motion ranges were compared to assess the effect of organ motion on dose delivery. Voxel dose variations occurred mostly in the high gradient regions, typically between the target volume and normal tissues, with a maximum variation up to 20%. The greatest CTV variation of all the plans was seen in the IMRT technique with the largest motion range (D99: -8.9%, D95: -8.3%, and D90: -6.3%). The greatest variation for all 3DCRT plans was less than 2% for D95. Dose variations for DARC fell between the 3DCRT and IMRT techniques. The dose volume histogram variations for normal organs were negligible. Therefore, the IMRT technique may be a preferable treatment choice in cases where the target volume and critical organs are in close proximity, or when normal organ protection is a high priority, provided that motion effect for the target volume can be managed.

Authors

Wu, QJ; Thongphiew, D; Wang, Z; Chankong, V; Yin, F-F

MLA Citation

Wu, QJ, Thongphiew, D, Wang, Z, Chankong, V, and Yin, F-F. "The impact of respiratory motion and treatment technique on stereotactic body radiation therapy for liver cancer." Med Phys 35.4 (April 2008): 1440-1451.

PMID

18491539

Source

pubmed

Published In

Medical Physics

Volume

35

Issue

4

Publish Date

2008

Start Page

1440

End Page

1451

DOI

10.1118/1.2839095

This report describes the technique and initial experience using cone beam CT (CBCT) for localization of treatment targets in patients undergoing stereotactic body radiation therapy (SBRT). Patients selected for SBRT underwent 3-D or 4-D CT scans in a customized immobilization cradle. GTV, CTV, ITV, and PTV were defined. Intensity-modulated radiation beams, multiple 3-D conformal beams, or dynamic conformal arcs were delivered using a Varian 21EX with 120-leaf MLC. CBCT images were obtained prior to each fraction, and registered to the planning CT by using soft tissue and bony structures to assure accurate isocenter localization. Patients were repositioned for treatment based on the CBCT images. Radiographic images (kV, MV, or CBCT) were taken before and after beam delivery to further assess set-up accuracy. Ten patients with lung, liver, and spine lesions received 29 fractions of treatment using this technique. The prescription doses ranged 1250 approximately 6000 cGy in 1 approximately 5 fractions. Compared to traditional 2-D matching using bony structures, CBCT corrects target deviation from 1 mm to 15 mm, with an average of 5 mm. Comparison of pre-treatment to post-treatment radiographic images demonstrated an average 2 mm deviation (ranging from 0-4 mm). Improved immobilization may enhance positioning accuracy. Typical total "in-room" times for the patients are approximately 1 hour. CBCT-guided SBRT is feasible and enhances setup accuracy using 3-D anatomical information.

Authors

Yin, F-F; Wang, Z; Yoo, S; Wu, QJ; Kirkpatrick, J; Larrier, N; Meyer, J; Willett, CG; Marks, LB

MLA Citation

Yin, F-F, Wang, Z, Yoo, S, Wu, QJ, Kirkpatrick, J, Larrier, N, Meyer, J, Willett, CG, and Marks, LB. "Integration of cone-beam CT in stereotactic body radiation therapy." Technology in Cancer Research & Treatment 7.2 (April 2008): 133-139.

PMID

18345702

Source

epmc

Published In

Technology in Cancer Research & Treatment

Volume

7

Issue

2

Publish Date

2008

Start Page

133

End Page

139

DOI

10.1177/153303460800700206

For intermediate and high risk prostate cancer, both the prostate gland and seminal vesicles are included in the clinical target volume. Internal motion patterns of these two organs vary, presenting a challenge for adaptive treatment. Adaptive techniques such as isocenter repositioning and soft tissue alignment are effective when tumor volumes only exhibit translational shift, while direct re-optimization of the intensity-modulated radiation therapy (IMRT) plan maybe more desirable when extreme deformation or differential positioning changes of the organs occur. Currently, direct re-optimization of the IMRT plan using beamlet (or fluence map) has not been reported. In this study, we report a novel on-line re-optimization technique that can accomplish plan adjustment on-line. Deformable image registration is used to provide position variation information on each voxel along the three dimensions. The original planned dose distribution is used as the 'goal' dose distribution for adaptation and to ensure planning quality. Fluence maps are re-optimized via linear programming, and a plan solution can be achieved within 2 min. The feasibility of this technique is demonstrated with a clinical case with large deformation. Such on-line ART process can be highly valuable with hypo-fractionated prostate IMRT treatment.

Authors

Wu, QJ; Thongphiew, D; Wang, Z; Mathayomchan, B; Chankong, V; Yoo, S; Lee, WR; Yin, F-F

MLA Citation

Wu, QJ, Thongphiew, D, Wang, Z, Mathayomchan, B, Chankong, V, Yoo, S, Lee, WR, and Yin, F-F. "On-line re-optimization of prostate IMRT plans for adaptive radiation therapy." Physics in Medicine and Biology 53.3 (February 2008): 673-691.

PMID

18199909

Source

epmc

Published In

Physics in Medicine and Biology

Volume

53

Issue

3

Publish Date

2008

Start Page

673

End Page

691

DOI

10.1088/0031-9155/53/3/011

The authors developed a hybrid multiresolution rigid-body registration technique to automatically register reference digital tomosynthesis (DTS) images with on-board DTS images to guide patient positioning in radiation therapy. This hybrid registration technique uses a faster but less accurate static method to achieve an initial registration, followed by a slower but more accurate adaptive method to fine tune the registration. A multiresolution scheme is employed in the registration to further improve the registration accuracy, robustness, and efficiency. Normalized mutual information is selected as the criterion for the similarity measure and the downhill simplex method is used as the search engine. This technique was tested using image data both from an anthropomorphic chest phantom and from eight head-and-neck cancer patients. The effects of the scan angle and the region-of-interest (ROI) size on the registration accuracy and robustness were investigated. The necessity of using the adaptive registration method in the hybrid technique was validated by comparing the results of the static method and the hybrid method. With a 44 degrees scan angle and a large ROI covering the entire DTS volume, the average of the registration capture ranges in single-axis simulations was between -31 and +34 deg for rotations and between -89 and +78 mm for translations in the phantom study, and between -38 and +38 deg for rotations and between -58 and +65 mm for translations in the patient study. Decreasing the DTS scan angle from 44 degrees to 22 degrees mainly degraded the registration accuracy and robustness for the out-of-plane rotations. Decreasing the ROI size from the entire DTS volume to the volume surrounding the spinal cord reduced the capture ranges to between -23 and +18 deg for rotations and between -33 and +43 mm for translations in the phantom study, and between -18 and +25 deg for rotations and between -35 and +39 mm for translations in the patient study. Results also showed that the hybrid registration technique had much larger capture ranges than the static method alone in registering the out-of-plane rotations.

Authors

Ren, L; Godfrey, DJ; Yan, H; Wu, QJ; Yin, F-F

MLA Citation

Ren, L, Godfrey, DJ, Yan, H, Wu, QJ, and Yin, F-F. "Automatic registration between reference and on-board digital tomosynthesis images for positioning verification." Med Phys 35.2 (February 2008): 664-672.

PMID

18383688

Source

pubmed

Published In

Medical Physics

Volume

35

Issue

2

Publish Date

2008

Start Page

664

End Page

672

DOI

10.1118/1.2831903

An intensity based six-degree image registration algorithm between cone-beam CT (CBCT) and planning CT has been developed for image-guided radiation therapy (IGRT). CT images of an anthropomorphic chest phantom were acquired using conventional CT scanner and corresponding CBCT was reconstructed based on projection images acquired by an on-board imager (OBI). Both sets of images were initially registered to each other using attached fudicial markers to achieve a golden standard registration. Starting from this point, an offset was applied to one set of images, and the matching result was found by a gray-value based registration method. Finally, The registration error was evaluated by comparing the detected shifts with the known shift. Three window-level (WL) combinations commonly used for image enhancement were examined to investigate the effect of anatomical information of Bony only (B), Bone+Tissue (BT), and Bone+Tissue+Air (BTA) on the accuracy and robustness of gray-value based registration algorithm. Extensive tests were performed in searching for the attraction range of registration algorithm. The widest attraction range was achieved with the WL combination of BTA. The average attraction ranges of this combination were 73.3 mm and 81.6 degree in the translation and rotation dimensions, respectively, and the average registration errors were 0.15 mm and 0.32 degree. The WL combination of BT shows the secondary largest attraction ranges. The WL combination of B shows limited convergence property and its attraction range was the smallest among the three examined combinations (on average 33.3 mm and 25.0 degree). If two sets of 3D images in original size (512 × 512) were used, registration could be accomplished within 10~20 minutes by current algorithm, which is only acceptable for off-line reviewing purpose. As the size of image set reduced by a factor of 2~4, the registration time would be 2~4 minutes which is feasible for on-line target localization.

Authors

Yan, H; Lei, R; Wu, J; Di, F; Yin, F-F

MLA Citation

Yan, H, Lei, R, Wu, J, Di, F, and Yin, F-F. "Evaluation of Image Enhancement Method on Target Registration Using Cone Beam CT in Radiation Therapy." Clinical medicine. Oncology 2 (January 2008): 289-299.

PMID

21892290

Source

epmc

Published In

Clinical Medicine: Oncology

Volume

2

Publish Date

2008

Start Page

289

End Page

299

Radiation therapy (RT) is a non-invasive and highly ekective treatment option for Prostate cancer. The goal is to deliver the prescription dose to the tumor (prostate) while minimizing the damages to the surrounding healthy organs namely bladder, rectum, and femoral heads. One major drawback of the conventional RT is that organ positions and shapes vary from day to day and that the original plan that is based on pre-treatment CT images may no longer be appropriate for treatment in subsequent sessions. The usual remedy is to include some margins surrounding the target when planning the treatment. Though this image guided radiation therapy technique allows in-room correction and can eliminate patient setup errors, the uncertainty due to organ deformation still remains. Performing a plan re-optimization will take about 30 minutes which makes it impractical to perform an online correction. In this paper, we develop an Adaptive Radiation Therapy (ART) system for online adaptive IMRT planning to compensate for the internal motion during the course of the prostate cancer treatment. It allows the treatment plan to be quickly modified based on the anatomy-of-the-day.

Authors

Thongphiew, D; Chankong, V; Yin, F-F; Wu, QJ

MLA Citation

Thongphiew, D, Chankong, V, Yin, F-F, and Wu, QJ. "An on-line adaptive radiation therapy system for intensity modulated radiation therapy: An application of multi-objective optimization." Journal of Industrial and Management Optimization 4.3 (2008): 453-475.

Source

scival

Published In

Journal of Industrial and Management Optimization

Volume

4

Issue

3

Publish Date

2008

Start Page

453

End Page

475

Adaptive radiation therapy (ART) requires an on-line modification of the treatment plan to compensate for the motion of organs. In this paper, an improved multi-leaf collimator (MLC) deformation approach is proposed to accurately compensate for the organ motion between the planning and treatment scans for ART. Instead of using slice-by-slice 2-D deformation field as in the original MLC deformation method, 3-D deformation field is first recovered by a volumetric deformable registration method to guide the MLC modification. In order to minimize the toxicity on organ-at-risk (OAR), the deformation fields of the OAR and planning target volume (PTV) are jointly used to adjust the MLC sequence of the original plan. The proposed approach has been applied to the radiotherapy for prostate cancer. Preliminary experimental results have demonstrated that the proposed method outperformed the original MLC approach with much reduced toxicity on OAR while maintaining great radiation efficacy on PTV. © 2008 Springer-Verlag Berlin Heidelberg.

Authors

Zhou, B; Xuan, J; Wu, Q; Wang, Y

MLA Citation

Zhou, B, Xuan, J, Wu, Q, and Wang, Y. "3-D deformation guided on-line modification of multi-leaf collimators for adaptive radiation therapy." Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 5112 LNCS (2008): 798-806.

Source

scival

Published In

Lecture Notes in Computer Science (Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Volume

5112 LNCS

Publish Date

2008

Start Page

798

End Page

806

DOI

10.1007/978-3-540-69812-8_79

Authors

Wu, QJ; Wang, Z; Kirkpatrick, JP; Chang, Z; Zhou, S; Willett, CG; Yin, F

MLA Citation

Wu, QJ, Wang, Z, Kirkpatrick, JP, Chang, Z, Zhou, S, Willett, CG, and Yin, F. "Dosimetrical evaluation of SRS/SBRT techniques." 2008.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

72

Issue

1

Publish Date

2008

Start Page

S650

End Page

S651

DOI

10.1016/j.ijrobp.2008.06.328

Authors

Wang, Z; Kirkpatrick, JP; Wu, QJ; Chang, Z; Willett, CG; Yin, F

MLA Citation

Wang, Z, Kirkpatrick, JP, Wu, QJ, Chang, Z, Willett, CG, and Yin, F. "Can cone beam CT replace frame-based localization for stereotactic radiosurgery?." 2008.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

72

Issue

1

Publish Date

2008

Start Page

S534

End Page

S534

DOI

10.1016/j.ijrobp.2008.06.070

Authors

Ren, L; Zhang, J; Thongphiew, D; Wu, Q; Godfrey, DJ; Zhou, S; Yin, F

MLA Citation

Ren, L, Zhang, J, Thongphiew, D, Wu, Q, Godfrey, DJ, Zhou, S, and Yin, F. "A novel digital tomosynthesis (DTS) reconstruction method using prior information and a deformation model." 2008.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

72

Issue

1

Publish Date

2008

Start Page

S109

End Page

S109

DOI

10.1016/j.ijrobp.2008.06.1014

Authors

Nelson, JW; Yoo, DS; Sampson, JH; Isaacs, RE; Larrier, NA; Marks, LB; Yin, FF; Wu, QJ; Wang, Z; Kirkpatrick, JP

MLA Citation

Nelson, JW, Yoo, DS, Sampson, JH, Isaacs, RE, Larrier, NA, Marks, LB, Yin, FF, Wu, QJ, Wang, Z, and Kirkpatrick, JP. "Stereotactic body radiosurgery of the spine: The duke experience." 2008.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

72

Issue

1

Publish Date

2008

Start Page

S489

End Page

S490

DOI

10.1016/j.ijrobp.2008.06.1438

Authors

Thongphiew, D; Wu, QJ; Lee, WR; Yoo, S; Chankong, V; Yin, F

MLA Citation

Thongphiew, D, Wu, QJ, Lee, WR, Yoo, S, Chankong, V, and Yin, F. "Dosimetrical evaluation of an online adaptive IMRT technique." 2008.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

72

Issue

1

Publish Date

2008

Start Page

S562

End Page

S562

DOI

10.1016/j.ijrobp.2008.06.132

Authors

Zhou, S; Das, S; Yin, F; Yoo, S; Lee, W; Yan, H; Wu, QJ; Wang, Z; Marks, L

MLA Citation

Zhou, S, Das, S, Yin, F, Yoo, S, Lee, W, Yan, H, Wu, QJ, Wang, Z, and Marks, L. "On-board CBCT observations support using adaptive non-uniform custom margins for prostate IGRT." 2008.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

72

Issue

1

Publish Date

2008

Start Page

S85

End Page

S86

DOI

10.1016/j.ijrobp.2008.06.961

PURPOSE: In this study, we investigate a technique of matching internal target volumes (ITVs) in four-dimensional (4D) simulation computed tomography (CT) to the composite target volume in free-breathing on-board cone-beam (CB) CT. The technique is illustrated by using both phantom and patient cases. METHODS AND MATERIALS: A dynamic phantom with a target ball simulating respiratory motion with various amplitude and cycle times was used to verify localization accuracy. The dynamic phantom was scanned using simulation CT with a phase-based retrospective sorting technique. The ITV was then determined based on 10 sets of sorted images. The size and epicenter of the ITV identified from 4D simulation CT images and the composite target volume identified from on-board CBCT images were compared to assess localization accuracy. Similarly, for two clinical cases of patients with lung cancer, ITVs defined from 4D simulation CT images and CBCT images were compared. RESULTS: For the phantom, localization accuracy between the ITV in 4D simulation CT and the composite target volume in CBCT was within 1 mm, and ITV was within 8.7%. For patient cases, ITVs on simulation CT and CBCT were within 8.0%. CONCLUSION: This study shows that CBCT is a useful tool to localize ITV for targets affected by respiratory motion. Verification of the ITV from 4D simulation CT using on-board free-breathing CBCT is feasible for the target localization of lung tumors.

Authors

Wang, Z; Wu, QJ; Marks, LB; Larrier, N; Yin, F-F

MLA Citation

Wang, Z, Wu, QJ, Marks, LB, Larrier, N, and Yin, F-F. "Cone-beam CT localization of internal target volumes for stereotactic body radiotherapy of lung lesions." Int J Radiat Oncol Biol Phys 69.5 (December 1, 2007): 1618-1624.

PMID

18035215

Source

pubmed

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

5

Publish Date

2007

Start Page

1618

End Page

1624

DOI

10.1016/j.ijrobp.2007.08.030

Authors

Wang, Z; Yin, F-F; Maurer, J; Wu, QJ; Hubbs, J; Marks, LB

MLA Citation

Wang, Z, Yin, F-F, Maurer, J, Wu, QJ, Hubbs, J, and Marks, LB. "Intra-fraction motion during tangential treatment of the left breast: how consistently is the heart actually blocked?." December 2007.

Source

wos-lite

Published In

Breast Cancer Research and Treatment

Volume

106

Publish Date

2007

Start Page

S194

End Page

S194

PURPOSE: High-precision intensity-modulated radiotherapy demands high patient positioning accuracy. On-board digital tomosynthesis (DTS) provides three-dimensional (3D) image guidance for daily positioning with a lower imaging dose, faster acquisition, and more geometric flexibility than 3D cone-beam computed tomography (CBCT). This clinical study evaluated DTS as a daily imaging technique for patient positioning and compared the results with 3D CBCT and two-dimensional (2D) radiography. METHODS AND MATERIALS: Head and neck cancer patients undergoing intensity-modulated radiotherapy were studied. For each session, the patient was positioned using laser marks. On-board imaging data sets, including 2D kilovoltage radiographs, DTS, and CBCT, were obtained to measure the daily patient positioning variations. The mean and standard deviations of the positioning variations in the translational and rotational directions were calculated. The positioning differences among 2D radiography, DTS, and CBCT were analyzed. RESULTS: Image data sets were collected from 65 treatment fractions for 10 patients. The systematic patient positioning variation was <0.10 cm and 1.0 degrees one dimensionally. The random variations were 0.27-0.34 cm in the translational and 0.93 degrees -1.99 degrees in the rotational direction. The mean vector isocenter variation was 0.48 cm. DTS with 40 degrees and 20 degrees scan angles in the coronal or sagittal directions yielded the same results for patient positioning. DTS performance was comparable to that of CBCT, with positioning differences of <0.1 cm and 0.5 degrees . The positioning difference between 2D radiography and DTS was approximately 0.1 cm and 0.2 cm in the vertical/longitudinal and lateral directions. CONCLUSION: Our results have demonstrated that DTS is a comparable 3D imaging technique to CBCT for daily patient positioning of head-and-neck patients as determined by manual registration of bony anatomy.

Authors

Wu, QJ; Godfrey, DJ; Wang, Z; Zhang, J; Zhou, S; Yoo, S; Brizel, DM; Yin, F-F

MLA Citation

Wu, QJ, Godfrey, DJ, Wang, Z, Zhang, J, Zhou, S, Yoo, S, Brizel, DM, and Yin, F-F. "On-board patient positioning for head-and-neck IMRT: comparing digital tomosynthesis to kilovoltage radiography and cone-beam computed tomography." Int J Radiat Oncol Biol Phys 69.2 (October 1, 2007): 598-606.

PMID

17869673

Source

pubmed

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

2

Publish Date

2007

Start Page

598

End Page

606

DOI

10.1016/j.ijrobp.2007.05.045

Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-angle scan, with typical scan angles ranging from 10 degrees to 40 degrees and acquisition times of less than 10 s. The resulting DTS slices show soft tissue contrast approaching that of full cone-beam CT. External beam radiotherapy target localization using DTS requires the registration of on-board DTS images with corresponding reference image data. This study evaluates three types of reference volume: original reference CT, exact reference DTS (RDTS), and a more computationally efficient approximate reference DTS (RDTSapprox), as well as three different DTS scan angles (22 degrees, 44 degrees, and 65 degrees) for the DTS target localization task. Three-dimensional mutual information (MI) shared between reference and onboard DTS volumes was computed in a region surrounding the spine of a chest phantom, as translations spanning +/-5 mm and rotations spanning +/-5 degrees were simulated along each dimension in the reference volumes. The locations of the MI maxima were used as surrogates for registration accuracy, and the width of the MI peaks were used to characterize the registration robustness. The results show that conventional treatment planning CT volumes are inadequate reference volumes for direct registration with on-board DTS data. The efficient RDTSapprox method also appears insufficient for MI-based registration without further refinement of the technique, though it may be suitable for manual registration performed by a human observer. The exact RDTS volumes, on the other hand, delivered a 3D DTS localization accuracy of 0.5 mm and 0.50 along each axis, using only a single 44 degrees coronal on-board DTS scan of the chest phantom.

Authors

Godfrey, DJ; Ren, L; Yan, H; Wu, Q; Yoo, S; Oldham, M; Yin, FF

MLA Citation

Godfrey, DJ, Ren, L, Yan, H, Wu, Q, Yoo, S, Oldham, M, and Yin, FF. "Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS)." Med Phys 34.8 (August 2007): 3374-3384.

PMID

17879800

Source

pubmed

Published In

Medical Physics

Volume

34

Issue

8

Publish Date

2007

Start Page

3374

End Page

3384

DOI

10.1118/1.2756941

Authors

Fuller, J; Wu, Q; Godfrey, D; Zhang, J; Wang, Z; Yoo, S; Yin, F

MLA Citation

Fuller, J, Wu, Q, Godfrey, D, Zhang, J, Wang, Z, Yoo, S, and Yin, F. "SU-FF-J-58: Clinical Evaluation Using Digital Tomosynthesis for Positioning Verification of Breath-Hold Liver Treatment." June 2007.

Source

crossref

Published In

Medical Physics

Volume

34

Issue

6Part5

Publish Date

2007

Start Page

2381

End Page

2381

DOI

10.1118/1.2760563

Authors

Wang, Z; Wu, QJ; Lee, WR; Yin, F

MLA Citation

Wang, Z, Wu, QJ, Lee, WR, and Yin, F. "Three-dimensional MRI and cone-beam CT matching for localization of prostate cancer treatment." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2379

End Page

2379

DOI

10.1118/1.2760553

Authors

Wang, Z; Nelson, J; Yoo, S; Wu, QJ; Kirkpatrick, J; Larrier, N; Meyer, J; Willett, C; Yin, F

MLA Citation

Wang, Z, Nelson, J, Yoo, S, Wu, QJ, Kirkpatrick, J, Larrier, N, Meyer, J, Willett, C, and Yin, F. "SU-FF-T-252: Improvement of Localization Accuracy by Using 3D Cone Beam CT for Stereotactic Body Radiation Therapy of Liver, Lung and Spine Lesions." June 2007.

Source

crossref

Published In

Medical Physics

Volume

34

Issue

6Part11

Publish Date

2007

Start Page

2459

End Page

2459

DOI

10.1118/1.2760913

Authors

Song, H; Chen, Z; Yue, N; Wu, QJ; Yin, F

MLA Citation

Song, H, Chen, Z, Yue, N, Wu, QJ, and Yin, F. "On the use of ice as a water-equivalent solid medium for brachytherapy dosimetry measurement." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2476

End Page

2476

DOI

10.1118/1.2760989

Authors

Thongphiew, D; Wu, Q; Chankong, V; Song, H; Yin, F

MLA Citation

Thongphiew, D, Wu, Q, Chankong, V, Song, H, and Yin, F. "A high MU efficiency dynamic MLC leaf sequencing algorithm." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2404

End Page

2404

DOI

10.1118/1.2760659

Authors

Wu, Q; Thongphiew, D; Wang, Z; Yin, F

MLA Citation

Wu, Q, Thongphiew, D, Wang, Z, and Yin, F. "The impact of SBRT treatment techniques on dose delivery in presence of organ motion and deformation." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2642

End Page

2642

DOI

10.1118/1.2761726

Authors

Wang, Z; Yin, F; Czito, B; Wu, QJ; Zhou, S; Willett, C

MLA Citation

Wang, Z, Yin, F, Czito, B, Wu, QJ, Zhou, S, and Willett, C. "Amplitude gated breath-hold treatment for upper abdominal lesions with on board imaging guidance." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2649

End Page

2649

DOI

10.1118/1.2761753

Authors

Thongphiew, D; Wu, Q; Chankong, V; Wang, Z; Yin, F

MLA Citation

Thongphiew, D, Wu, Q, Chankong, V, Wang, Z, and Yin, F. "On-line re-optimization of prostate IMRT plans for image guided adaptive radiation therapy." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2328

End Page

2328

DOI

10.1118/1.2760335

Authors

Zhang, J; Wu, Q; Godfrey, D; Yin, F

MLA Citation

Zhang, J, Wu, Q, Godfrey, D, and Yin, F. "WE-E-M100F-01: 3D Interfraction Position Verification for Patients Undergoing Partial Breast Irradiation: Comparing Digital Tomosynthesis to Cone-Beam CT." June 2007.

Source

crossref

Published In

Medical Physics

Volume

34

Issue

6Part21

Publish Date

2007

Start Page

2607

End Page

2607

DOI

10.1118/1.2761583

Authors

Yin, F; Yoo, S; Wu, Q

MLA Citation

Yin, F, Yoo, S, and Wu, Q. "Performing concurrent kilovoltage imaging while delivering megavoltage treatment beams." June 2007.

Source

wos-lite

Published In

Medical Physics

Volume

34

Issue

6

Publish Date

2007

Start Page

2564

End Page

2565

DOI

10.1118/1.2761412

Authors

Wu, Q; Fuller, J; Godfrey, D; Zhang, J; Wang, Z; Willet, C; Yin, F

MLA Citation

Wu, Q, Fuller, J, Godfrey, D, Zhang, J, Wang, Z, Willet, C, and Yin, F. "Clinical evaluation of digital tomosynthesis for target localization in breath-hold liver treatment." 2007.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

3

Publish Date

2007

Start Page

S129

End Page

S130

DOI

10.1016/j.ijrobp.2007.07.240

Authors

Fuller, JG; Wu, Q; Godfrey, D; Zhang, J; Wang, Z; Willet, C; Yin, F

MLA Citation

Fuller, JG, Wu, Q, Godfrey, D, Zhang, J, Wang, Z, Willet, C, and Yin, F. "The effect of scan angle on target localization accuracy using digital tomosynthesis." 2007.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

3

Publish Date

2007

Start Page

S628

End Page

S629

DOI

10.1016/j.ijrobp.2007.07.1959

Authors

Wang, Z; Wu, Q; Kirkpatrick, JP; Willett, CG; Yin, F

MLA Citation

Wang, Z, Wu, Q, Kirkpatrick, JP, Willett, CG, and Yin, F. "Localization for MRI-based radiation treatment of intracranial lesions by using three-dimensional MRI and cone-beam CT matching." 2007.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

3

Publish Date

2007

Start Page

S189

End Page

S189

DOI

10.1016/j.ijrobp.2007.07.341

Authors

Thengphiew, D; Wu, Q; Wang, Z; Yoo, S; Lee, WR; Vujaskovic, Z; Yin, F

MLA Citation

Thengphiew, D, Wu, Q, Wang, Z, Yoo, S, Lee, WR, Vujaskovic, Z, and Yin, F. "On-line adaptive planning system for prostate IMRT treatment." 2007.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

3

Publish Date

2007

Start Page

S20

End Page

S21

Authors

Yoo, S; Wu, Q; Godfrey, D; Yan, H; Ren, L; Yin, F

MLA Citation

Yoo, S, Wu, Q, Godfrey, D, Yan, H, Ren, L, and Yin, F. "Clinical evaluation of digital tomosynthesis in positioning verification based on bony anatomy and soft-tissue for prostate IMRT treatment." 2007.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

69

Issue

3

Publish Date

2007

Start Page

S640

End Page

S641

DOI

10.1016/j.ijrobp.2007.07.1978

Authors

Song, H; Wu, Q; Bowsher, J; Yin, F

MLA Citation

Song, H, Wu, Q, Bowsher, J, and Yin, F. "Imaging with brachytherapy sources." June 2006.

Source

wos-lite

Published In

Medical Physics

Volume

33

Issue

6

Publish Date

2006

Start Page

2108

End Page

2108

DOI

10.1118/1.2241183

Authors

Song, H; Wu, Q; Steffey, B; Yin, F

MLA Citation

Song, H, Wu, Q, Steffey, B, and Yin, F. "Conservation of integrated reference air kerma." June 2006.

Source

wos-lite

Published In

Medical Physics

Volume

33

Issue

6

Publish Date

2006

Start Page

2083

End Page

2083

DOI

10.1118/1.2241075

Authors

Wang, Z; Yin, F; Yoo, S; Wu, Q; Willett, C; Marks, L

MLA Citation

Wang, Z, Yin, F, Yoo, S, Wu, Q, Willett, C, and Marks, L. "Verifying internal target volume using cone-beam CT for stereotactic body radiotherapy treatment." June 2006.

Source

wos-lite

Published In

Medical Physics

Volume

33

Issue

6

Publish Date

2006

Start Page

1991

End Page

1991

DOI

10.1118/1.2240160

Authors

Wang, Z; Yin, F; Marks, L; Wu, Q; Yoo, S; Willett, C

MLA Citation

Wang, Z, Yin, F, Marks, L, Wu, Q, Yoo, S, and Willett, C. "Intra- and inter-breath-hold position variations for OBI guided amplitude gating treatment with breath hold." June 2006.

Source

wos-lite

Published In

Medical Physics

Volume

33

Issue

6

Publish Date

2006

Start Page

2040

End Page

2040

DOI

10.1118/1.2240863

Authors

Yin, F; Yoo, S; Wang, Z; Godfrey, D; Wu, Q

MLA Citation

Yin, F, Yoo, S, Wang, Z, Godfrey, D, and Wu, Q. "MO-A-224C-01: Daily Localization I: KV/CBCT." June 2006.

Source

crossref

Published In

Medical Physics

Volume

33

Issue

6Part14

Publish Date

2006

Start Page

2155

End Page

2155

DOI

10.1118/1.2241392

Authors

Wu, Q; Yan, H; Yin, F; Yoo, S; Das, S; Willett, C

MLA Citation

Wu, Q, Yan, H, Yin, F, Yoo, S, Das, S, and Willett, C. "A tool for off-line review of 3D target verification and localization with cone-beam computed tomography." June 2006.

Source

wos-lite

Published In

Medical Physics

Volume

33

Issue

6

Publish Date

2006

Start Page

2023

End Page

2023

DOI

10.1118/1.2240795

Authors

Wu, Q

MLA Citation

Wu, Q. "3D target localization using cone-beam CT for head and neck IMRT patients." June 2006.

Source

wos-lite

Published In

Medical Physics

Volume

33

Issue

6

Publish Date

2006

Start Page

2020

End Page

2020

DOI

10.1118/1.2240782

Authors

Wu, Q; Godfrey, DJ; Wang, Z; Yoo, S; Brizel, DM; Yin, F

MLA Citation

Wu, Q, Godfrey, DJ, Wang, Z, Yoo, S, Brizel, DM, and Yin, F. "Clinical efficacy of 3D target localization using on-board digital tomosynthesis in head and neck treatment." 2006.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

66

Issue

3

Publish Date

2006

Start Page

S143

End Page

S144

DOI

10.1016/j.ijrobp.2006.07.289

Authors

Yin, F; Wang, Z; Yoo, S; Wu, Q; Kirkpatrick, J; Meyer, J; Larrier, N; Willett, C; Marks, L

MLA Citation

Yin, F, Wang, Z, Yoo, S, Wu, Q, Kirkpatrick, J, Meyer, J, Larrier, N, Willett, C, and Marks, L. "Use of on-board imaging to evaluate residual errors for target localization in SBRT: A feedback analysis." 2006.

Source

wos-lite

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

66

Issue

3

Publish Date

2006

Start Page

S145

End Page

S145

DOI

10.1016/j.ijrobp.2006.07.292

Authors

Changkon, V; Jitprapaikulsarn, S; Thongphiew, D; Wessels, B; Wu, Q

MLA Citation

Changkon, V, Jitprapaikulsarn, S, Thongphiew, D, Wessels, B, and Wu, Q. "TU-C-T-617-01: A Computer Model for Automatic Planning and Optimization for Gamma Knife Radiosurgery Using Auto-Positioning System." Medical Physics 32.6Part16 (June 2005): 2086-2086.

Source

crossref

Published In

Medical Physics

Volume

32

Issue

6Part16

Publish Date

2005

Start Page

2086

End Page

2086

DOI

10.1118/1.1999759

The challenges of real-time Gamma Knife™ inverse planning are the large number of variables involved and the unknown search space a priori. With limited collimator sizes, shots have to be heavily overlapped to form a smooth prescription isodose line that conforms to the irregular target shape. Such overlaps greatly influence the total number of shots per plan, making pre-determination of the total number of shots impractical. However, this total number of shots usually defines the search space, a pre-requisite for most of the optimization methods. Since each shot only covers part of the target, a collection of shots in different locations and various collimator sizes selected makes up the global dose distribution that conforms to the target. Hence, planning or placing these shots is a combinatorial optimization process that is computationally expensive by nature. We have previously developed a theory of shot placement and optimization based on skeletonization. The real-time inverse planning process, reported in this paper, is an expansion and the clinical implementation of this theory. The complete planning process consists of two steps. The first step is to determine an optimal number of shots including locations and sizes and to assign initial collimator size to each of the shots. The second step is to fine-tune the weights using a linear-programming technique. The objective function is to minimize the total dose to the target boundary (i.e., maximize the dose conformity). Results of an ellipsoid test target and ten clinical cases are presented. The clinical cases are also compared with physician's manual plans. The target coverage is more than 99% for manual plans and 97% for all the inverse plans. The RTOG PITV conformity indices for the manual plans are between 1.16 and 3.46, compared to 1.36 to 2.4 for the inverse plans. All the inverse plans are generated in less than 2 min, making real-time inverse planning a reality. © 2003 American Association of Physicists in Medicine.

Authors

Wu, QJ; Chankong, V; Jitprapaikulsarn, S; Wessels, BW; Einstein, DB; Mathayomchan, B; Kinsella, TJ

MLA Citation

Wu, QJ, Chankong, V, Jitprapaikulsarn, S, Wessels, BW, Einstein, DB, Mathayomchan, B, and Kinsella, TJ. "Real-time inverse planning for Gamma Knife radiosurgery." Medical Physics 30.11 (2003): 2988-2995.

PMID

14655946

Source

scival

Published In

Medical Physics

Volume

30

Issue

11

Publish Date

2003

Start Page

2988

End Page

2995

DOI

10.1118/1.1621463

Purpose: To develop a novel dose optimization algorithm for improving the sparing of critical structures during gamma knife radiosurgery by shaping the plug pattern of each individual shot. Method and Materials: We first use a geometric information (medial axis) aided guided evolutionary simulated annealing (GESA) optimization algorithm to determine the number of shots and isocenter location, size, and weight of each shot. Then we create a plug quality score system that checks the dose contribution to the volume of interest by each plug in the treatment plan. A positive score implies that the corresponding source could be open to improve tumor coverage, whereas a negative score means the source could be blocked for the purpose of sparing normal and critical structures. The plug pattern is then optimized via the GESA algorithm that is integrated with this score system. Weight and position of each shot are also tuned in this procedure. Results: An acoustic tumor case is used to evaluate our algorithm. Compared to the treatment plan generated without plug patterns, adding an optimized plug pattern into the treatment planning process boosts tumor coverage index from 95.1% to 97.2%, reduces RTOG conformity index from 1.279 to 1.167, lowers Paddick's index from 1.34 to 1.20, and trims the critical structure receiving more than 30% maximum dose from 16 mm3 to 6 mm3. Conclusions: Automated GESA-based plug pattern optimization of gamma knife radiosurgery frees the treatment planning team from the manual forward planning procedure and provides an optimal treatment plan. © 2003 Elsevier Science Inc.

Authors

Zhang, P; Wu, J; Dean, D; Xing, L; Xue, J; Maciunas, R; Sibata, C

MLA Citation

Zhang, P, Wu, J, Dean, D, Xing, L, Xue, J, Maciunas, R, and Sibata, C. "Plug pattern optimization for gamma knife radiosurgery treatment planning." International Journal of Radiation Oncology Biology Physics 55.2 (2003): 420-427.

PMID

12527055

Source

scival

Published In

International Journal of Radiation Oncology Biology Physics

Volume

55

Issue

2

Publish Date

2003

Start Page

420

End Page

427

DOI

10.1016/S0360-3016(02)04145-7

Authors

Zhang, P; Wu, J; Wang, Z; Sibata, C

MLA Citation

Zhang, P, Wu, J, Wang, Z, and Sibata, C. "Considerations for the implementation of target volume protocols in radiation therapy: In regard to Craig et al., IJROBP 2001;49:241-250 (multiple letters) [2]." International Journal of Radiation Oncology Biology Physics 52.5 (2002): 1424-1425.

PMID

11955759

Source

scival

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

52

Issue

5

Publish Date

2002

Start Page

1424

End Page

1425

DOI

10.1016/S0360-3016(01)02802-4

Stepped leaf edges are the major limitation of conforming to the prescribed treatment contour defined by the conventional multileaf collimator (MLC), which produces a scalloped dose pattern. The commercial HD-270 MLC™ (HDI) technique provides a software solution of the conventional MLC to achieve smoothed edge and optimal penumbra of the MLC shaped field. We implemented the HDI functionality on a 3D treatment planning system and compared the dosimetric effects of the HDI delivery in simulation with those in experiment for a number of the MLC fields. The fields from the contour of varied shapes with different sizes of the leaf stepping were tested for the HDI delivery. There is a good agreement of the dose distribution between the calculation as implemented in the planning system and the measurement performed on the treatment machine. It has been shown that the HDI delivery significantly smoothes the stepped field edge with the reduced isodose undulation and effective penumbra. A problem may be present when the HDI is applied for the treatment of the circular contour of smaller diameter, and the conformity of the MLC shaping may not be achievable satisfactorily with the existing system. The optimization of leaf configuration is suggested to improve the conformity of the HDI technique. The HDI planning then can be used to assist in the decision making of applying the HDI treatment delivery. © 2002 American Association of Physicists in Medicine.

Authors

Xue, J; Zhang, P; Wu, J; Wang, Z; Sibata, C

MLA Citation

Xue, J, Zhang, P, Wu, J, Wang, Z, and Sibata, C. "Implementation of the isocenter-shift technique for smoothing MLC field edge on a 3D treatment planning system." Medical Physics 29.7 (2002): 1413-1420.

PMID

12148721

Source

scival

Published In

Medical Physics

Volume

29

Issue

7

Publish Date

2002

Start Page

1413

End Page

1420

DOI

10.1118/1.1485061

The response of a digital computed radiography system to the megavoltage therapeutic radiation beams was invested. A narrow slit of radiation beam was used to test the line spread function of the system. The effects of various facts such as cassette, beam energy, radiation dose, scanning orientation and timing on the line spread function were investigated. The calibration curves were established to calibrate the image intensity to the megavoltage radiation dose. The calibration curves were applied to measure the beam profiles of the radiation fields with various wedges.

Authors

Wang, Z; Wu, QJ; Sibata, CH

MLA Citation

Wang, Z, Wu, QJ, and Sibata, CH. "Megavoltage radiation dose response of digital computed radiography." Proceedings of SPIE - The International Society for Optical Engineering 4320 (2001): 236-243.

Source

scival

Published In

Proceedings of SPIE - The International Society for Optical Engineering

Volume

4320

Publish Date

2001

Start Page

236

End Page

243

DOI

10.1117/12.430958

A prototype high definition multi-leaf collimator system (HDI) has been developed and installed on the linear accelerator for use in conformal radiotherapy. The HDI technique utilizes the dynamic shift of the 3D-target volume to feather the multi-leaf collimator defined field edges. During each feathering, the leaf positions are adjusted according to the updated target image projected into the MLC plane. The purpose of this study is to demonstrate that this device can improve spatial resolution of a conformal radiation therapy treatment. The results of this study indicate that the HDI technique can be a useful tool for treating small, or highly irregular shaped targets, and for sparing adjacent critical structures for certain cases.

Authors

Wu, QJ; Wang, Z; Sibata, C

MLA Citation

Wu, QJ, Wang, Z, and Sibata, C. "Improving spatial resolution of multileaf collimator defined radiation treatment field." Proceedings of SPIE - The International Society for Optical Engineering 4319 (2001): 69-75.

Source

scival

Published In

Proceedings of SPIE - The International Society for Optical Engineering

Volume

4319

Publish Date

2001

Start Page

69

End Page

75

DOI

10.1117/12.428112

The use of three-dimensional (3D) treatment planning computers for determining seed placement in prostate brachytherapy has become more widespread. This study compares the dosimetric differences between prostate implants performed by using 3D treatment planning computers vs the traditional nomogram approach. During a five-month period, 19 transperineal ultrasound-guided conformal prostatic implants were performed. Of these patients, 14 received a planning computed tomography (CT) scan with nomogram approach, while five patients underwent planning ultrasound with 3D computerized treatment planning. All patients underwent postoperative CT scans for dosimetric analysis. Implants were evaluated based on the percentage of prostate receiving the prescribed dose, minimal dose received by 100% and 90% of the prostate, and dose to the urethra and rectal mucosa. Results showed all patients had adequate glandular coverage, and there were no statistically significant dosimetric differences between the two groups. However, the 3D treatment planning group did require fewer mCi/cc compared with the nomogram group. Use of 3D treatment planning computers or nomogram- based treatment planning can provide equivalent dosing for prostate implants when performed by an experienced brachytherapist; however, the use of a 3D treatment planning and linear array ultrasound probe should greatly decrease the involved learning curve.

Authors

Ellis, R; Wu, QJ; Sajja, R; Murphy, C; Rustgi, S; Mackay, W; Resnick, M; Kinsella, T

MLA Citation

Ellis, R, Wu, QJ, Sajja, R, Murphy, C, Rustgi, S, Mackay, W, Resnick, M, and Kinsella, T. "Three-dimensional treatment planning computer-based vs nomogram-based implant technique for prostate carcinoma." Journal of Brachytherapy International 16.1 (2000): 55-61.

Source

scival

Published In

Journal of Brachytherapy International

Volume

16

Issue

1

Publish Date

2000

Start Page

55

End Page

61

The Leksell stereotactic Gamma Knifetrade mark uses radiation from 201 (60)Co sources that are focused to the center of a collimator helmet to deliver a high dose of radiation with minimal irradiation of proximal structures. This paper presents a method for fast verification of the irradiation time as calculated by the Leksell Gamma Knifetrade mark treatment planning software GammaPlan((R)). To obtain the irradiation time for each shot in the treatment plan, one must first accurately calculate the tissue maximum ratio (TMR) for each of the individual 201 beams. The algorithm presented in this paper begins with the determination of the geometrical relationship between the Gamma Knifetrade mark collimator helmet and the stereotactic frame. A group of reference points is measured to build a head model simulating the patient skull geometry. During radiosurgery, the isocenter of the collimator helmet is moved to the shot center. A group of spatial vectors describing the reference points at the skull surface is obtained by converting the Cartesian coordinates to Polar coordinates. For each individual beam, the three nearest reference vectors are found by ranking the relative angles. The depth that each beam penetrates the patient's skull to the isocenter is obtained via linear interpolation. The TMR for each beam then is compared with the TMR for the calibration setup, which is done using a spherical 8 cm radius phantom. This algorithm is applied to verify the treatment time calculated in GammaPlan((R)) Version 5.2. The results are shown to agree with GammaPlan((R)) within 3%.

Authors

Zhang, P; Dean, D; Wu, QJ; Sibata, C

MLA Citation

Zhang, P, Dean, D, Wu, QJ, and Sibata, C. "Fast verification of Gamma Knifetrade mark treatment plans." Journal of applied clinical medical physics [electronic resource] / American College of Medical Physics 1.4 (2000): 158-164.

PMID

11674832

Source

scival

Published In

Journal of applied clinical medical physics [electronic resource] / American College of Medical Physics

Volume

1

Issue

4

Publish Date

2000

Start Page

158

End Page

164

This paper describes a new algorithm for skeletonization of two- (2D) and three-dimensional (3D) objects based on ridge extraction. Ridges are formed when grassfire fronts collapse during grassfire propagation and they correspond to the locus of skeleton. The iso-distance contours/surfaces of a distance map are analogous to the grassfire fronts. They are locally smooth everywhere except at ridge locations. The new skeletonization algorithm extracts these ridge points based on local curvature measurement and is rotational invariant. It requires one scan of the image for curvature detection in any dimension, and is much faster than thinning methods. Connectivity checks are not required and the algorithm is extensible to higher dimensions. Our 3D skeletonization method is used in a novel algorithm to guide computerized planning of radiosurgical treatment of brain tumors. (C) 2000 Elsevier Science Ltd.

Authors

Wu, QJ; Bourland, JD

MLA Citation

Wu, QJ, and Bourland, JD. "Three-dimensional skeletonization for computer-assisted treatment planning in radiosurgery." Computerized Medical Imaging and Graphics 24.4 (2000): 243-251.

PMID

10842048

Source

scival

Published In

Computerized Medical Imaging and Graphics

Volume

24

Issue

4

Publish Date

2000

Start Page

243

End Page

251

DOI

10.1016/S0895-6111(00)00010-0

This work provides a method for an independent check of Gamma Knife® GammaPlan® radio-surgery calculations, named the spherical approximation method or SAM. Based on skull dimension measurements, the treated volume of the head is modeled as a sphere of radius R. With this approximation, an analytical solution for fast ray tracing of the path length, for each of the 201 beamlets, of the Gamma Knife helmet collimator was possible. The dose rate at the focus of a single shot is the sum of the contributions of all active beamlets adjusted for both the collimator factor and attenuation. For an arbitrary point, the dose rate is derived at the beamlet level from the focus values adjusted for the new path length attenuation and the appropriate collimators' off-axis profiles. The sum over all beamlets' contributions gives the dose rate at that particular point. At the single shot level, SAM independent check results agree with the GammaPlan® for patient calculations to better than ±6% and, as expected, in spherical phantoms the agreements improve to better than ±1.0%. For an arbitrary point, multi-shot procedure, the agreement is better than ±3% and ±1.5, respectively. (C) 2000 American Association of Physicists in Medicine.

Authors

Marcu, SM; Wu, QJ; Pillai, K; Weinhous, MS

MLA Citation

Marcu, SM, Wu, QJ, Pillai, K, and Weinhous, MS. "GammaPlan® - Leksell Gamma Knife® radiosurgery treatment planning verification method." Medical Physics 27.9 (2000): 2146-2149.

PMID

11011744

Source

scival

Published In

Medical Physics

Volume

27

Issue

9

Publish Date

2000

Start Page

2146

End Page

2149

DOI

10.1118/1.1287051

Multileaf collimators were applied to intensity modulated lateral fields to achieve a relatively homogeneous dose distribution in the head and neck region without using any wedges. Then the isodose distribution was compared with one planned with wedges. As a result, the many advantages of intensity modulated planning were highlighted.

Authors

Wang, Z; Sibata, CH; Wu, QJ; Kinsella, TJ

MLA Citation

Wang, Z, Sibata, CH, Wu, QJ, and Kinsella, TJ. "A reliable intensity modulated radiation therapy approach with multiple opposed lateral fields for head and neck tumors." Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings 1 (2000): 232-234.

Source

scival

Published In

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings

Volume

1

Publish Date

2000

Start Page

232

End Page

234

This work merges two distinct fields, 3D morphology and ionizing radiation dosimetry, to solve the problem of 3D-treatment planning and optimization in stereotactic radiosurgery. In Leksell Gamma Knife radiosurgery, dose delivery is based on the unit 'shot,' a dose distribution approximately spherical in shape, Multiple shots, or isocenters, are used in Gamma Knife treatment to deliver a conformal dose to an irregular radiosurgical target. The medial axis transformation, or skeleton, of the target, which uniquely characterizes the target volume and shape, is used to determine the optimal shot positions (isocenters), sizes (collimator helmet size and dosimetric weight), and the total number of shots that will deliver a conformal dose distribution to the target. The skeletonization approach reduces a complicated 3D-optimization problem to 1D searching with potential savings in computation time and mathematical complexity. In addition, optimization based on target shape replicates and automates manual treatment planning. This approach makes the process easily understandable. The relationship between skeleton discs and the dose distributions they predict is discussed. Results of optimal plans and corresponding dose distributions are presented. This approach is generally applicable to other types of multi- isocentric stereotactic radiosurgery techniques.

Authors

Wu, QJ; Bourland, JD

MLA Citation

Wu, QJ, and Bourland, JD. "Morphology-guided radiosurgery treatment planning and optimization for multiple isocenters." Medical Physics 26.10 (1999): 2151-2160.

PMID

10535632

Source

scival

Published In

Medical Physics

Volume

26

Issue

10

Publish Date

1999

Start Page

2151

End Page

2160

DOI

10.1118/1.598731

Purpose: In this study we examine the influence of x-ray energy on the uniformity of the dose within the lung in total-body irradiation treatments in which partial transmission blocks are used to control the lung dose. Methods and Materials: A solid water phantom with a cork insert to simulate a lung was irradiated by x-rays with energies of either 6, 10, or 18 MV. The source to phantom distance was 3.9 meters. The cork insert was either 10 cm wide or 6 cm wide. Partial transmission blocks with transmission factors of 50% were placed anterior to the cork insert. The blocks were either 8 or 4 cm in width. Kodak XV-2 film was placed in the midline of the phantom to record the dose. Midplane dose profiles were measured with a densitometer. Results: For the 10 cm wide cork insert the uniformity of the dose over 80% of the block width varied from 6.6% for the 6 MV x-rays to 12.2% for the 18 MV x- rays. For the 6 cm wide cork insert the uniformity was comparable for all three x-ray energies, but for 18 MV the central dose increased by 9.4% compared to the 10 cm wide insert. Conclusion: Many factors must be considered in optimizing the dose for total-body irradiation. This study suggests that for AP/PA techniques lung dose uniformity is superior with 6 MV irradiation. The blanket recommendation that the highest x-ray energy be used in TBI is not valid for all situations.

Authors

Ekstrand, K; Greven, K; Wu, Q

MLA Citation

Ekstrand, K, Greven, K, and Wu, Q. "The influence of x-ray energy on lung dose uniformity in total-body irradiation." International Journal of Radiation Oncology Biology Physics 38.5 (1997): 1131-1136.

PMID

9276381

Source

scival

Published In

International Journal of Radiation Oncology, Biology, Physics

Volume

38

Issue

5

Publish Date

1997

Start Page

1131

End Page

1136

DOI

10.1016/S0360-3016(97)00286-1

In gamma unit radiosurgery treatment planning, dose delivery is based on the unit 'shot,' a distribution of dose approximately spherical in shape. Multiple shots are used to cover different parts of a given target region. Effective 3D optimization for gamma unit treatment has not been previously reported. In this article, a novel optimization method is introduced based on medial axis transformation techniques. Given a defined target volume, the target's medial axis, which uniquely characterizes the target, is used to determine the optimal shot positions and sizes. In using the medial axis, the 3D optimization problem is reduced to a 1D optimization, with corresponding savings in computational time and mathematical complexity. In addition, optimization based on target shape replicates and automates manual treatment planning, which makes the process easily understandable. Results of optimal plans and the corresponding dose distributions are presented. The relationship between skeleton disks and the dose distributions they predict are also discussed.

Authors

Wu, Q; Bourland, JD; Robb, RA

MLA Citation

Wu, Q, Bourland, JD, and Robb, RA. "Morphology-guided radiotherapy treatment planning and optimization." Proceedings of SPIE - The International Society for Optical Engineering 2707 (1996): 180-189.

Source

scival

Published In

Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics

Volume

2707

Publish Date

1996

Start Page

180

End Page

189

The medial axis analysis of an object can be used to effectively guide and optimize radiosurgery treatment planning. In this paper, a fast Euclidean medial axis transformation in three dimensions based on dynamic grassfire simulation and ridge extraction is presented. A ridge occurs when fire fronts collapse during grassfire propagation. Iso-contours(2D) or iso-surfaces(3D) can be obtained from dynamic grassfire transforms. They are locally smooth everywhere except at ridge locations. Ridges are detected by measuring local curvature at each point. This process is invariant under spatial translations and rotations. The algorithm yields the true Euclidean skeleton of the objects and is several orders of magnitude faster than other thinning methods. In radiosurgery treatment planning, optimal shots are only placed on the medial axis of the 3D target, which reduces optimization time and complexity. An example of a treatment planning process will be presented and the relationship between skeleton disks and the dose distributions which they predict will be discussed.

Authors

Wu, QR; Bourland, JD; Robb, RA

MLA Citation

Wu, QR, Bourland, JD, and Robb, RA. "Fast 3D medial axis transformation to reduce computation and complexity in radiosurgery treatment planning." Proceedings of SPIE - The International Society for Optical Engineering 2710 (1996): 562-571.

Source

scival

Published In

Proceedings of SPIE - The International Society for Optical Engineering

Volume

2710

Publish Date

1996

Start Page

562

End Page

571

DOI

10.1117/12.237959

Authors

Sheng, Y; Ge, Y; Yuan, L; Li, T; Yin, F-F; Wu, QJ

MLA Citation

Sheng, Y, Ge, Y, Yuan, L, Li, T, Yin, F-F, and Wu, QJ. "Outlier identification in radiation therapy knowledge-based planning: A study of pelvic cases (Published online)." Medical Physics.

Source

crossref

Published In

Medical Physics

DOI

10.1002/mp.12556