- Email: [email protected]
QRRO Survey: A Proof of Principle Study
Proceedings of the 53rd Annual ASTRO Meeting Conclusions: With a median follow-up of 9.0 years, this prospective randomized trial identified equivalent cause-specific, biochemical progression-free and overall survival in the 20 Gy and 44 Gy arms. It is probable that the lack of benefit for a higher supplemental XRT dose is the result of high quality brachytherapy dose distributions. Author Disclosure: G.S. Merrick: None. K.E. Wallner: None. A.V. Taira: None. W.M. Butler: None. R.W. Galbreath: None. E. Adamovich: None.
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Improving Prostate Brachytherapy Quality Assurance with MRI-based Sector Analysis in a Phase II Prospective Trial
A. P. Brown, T. J. Pugh, D. A. Swanson, R. J. Kudchadker, T. L. Bruno, E. N. Christensen, S. J. Frank MD Anderson Cancer Center, Houston, TX Purpose/Objective(s): Sector analysis is a clinical tool that can be used in the post-implant quality assurance process for prostate brachytherapy by calculating the dose delivered to different sectors within the prostate. Each sector can be correlated to biopsy results for individual patients. However, sector analysis has not been translated to clinical practice, in part due to poor anatomic visualization of the prostate base and apex on post-implant CT scans. The purpose of this study is to evaluate MRI-based sector analysis as a method to improve the post-implant quality assurance process of brachytherapy. Materials/Methods: Fifty intermediate-risk prostate cancer patients received I-125 brachytherapy as monotherapy in a prospective Phase II clinical trial. Day 30 post-implant MRI and CT scans were fused to optimize prostate visualization on MRI and seed identification on CT. Sector analysis was performed by dividing the prostate into 6 sectors that can be correlated to pathology results, specifically the right and left portions of the base, mid-gland and apex. Sector analysis dosimetry (V100, D90, and D100) was then performed on each sector for the ultrasound (US) treatment plan, and then compared to post-implant sector analysis dosimetry calculated using CT alone and MRI-CT fusion. Results: Twenty-four of 50 patients had positive biopsies at the base, 34 at the mid gland, and 27 at the apex. Post-implant doses for the whole prostate using MRI-CT fusion (V100 = 91.3% and D90 = 152.9 Gy) were significantly lower than both US planned doses (100%; 188.9 Gy), and doses calculated using CT alone (98.5%; 183.6 Gy) (p \ 0.0001). Sector analysis showed that the area of the prostate most responsible for the discrepancy in dose delivered was at the prostate base, where the dose from MRI-CT fusion (V100 = 79% and D90 = 130 Gy) was significantly lower than both US planned (100%; 200 Gy) and post-implant CT alone (96%; 170 Gy) (p \ 0.0001). The minimum dose delivered (D100) to the base on MRI-CT fusion (mean = 86 Gy) was significantly lower than US planned doses (157 Gy) and had a wider range (35 – 151 Gy vs. 133 – 178 respectively) (p \ 0.0001). Conclusions: MRI-based sector analysis provides a comprehensive and accurate assessment of the dose delivered to specified regions within the prostate following brachytherapy. Standard post-implant dosimetry using CT alone overestimated the dose delivered to the prostate. Sector analysis further revealed a 35% mean reduction of the planned dose at the base, where 48% of patients had biopsy-proven cancer. MRI-based sector analysis can be used to correlate the dose delivered with pathology results, outcomes, and toxicity to improve quality assurance and optimize treatment delivery in prostate brachytherapy. Author Disclosure: A.P. Brown: None. T.J. Pugh: None. D.A. Swanson: None. R.J. Kudchadker: None. T.L. Bruno: None. E.N. Christensen: None. S.J. Frank: None.
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Secure Web-based Remote Quality Assessment of Prostate Brachytherapy Treatment Plans for a Multiinstitutional Patterns of Care/QRRO Survey: A Proof of Principle Study
P. M. Devlin1, M. J. Zelefsky2, G. N. Cohen3, P. L. Nguyen1, C. L. Crozier4, J. Owen4, C. M. Rose5, J. Wilson6, W. R. Bosch7 1
Brigham & Women’s Hospital, Boston, MA, 2Memorial Sloan Kettering Cancer Center, New York, NY, 3MSKCC, New York, NY, American College of Radiology, Philadelphia, PA, 5QRRO, Los Angeles, CA, 6Medical College of Wisconsin, Milwaukee, WI, 7 ITC, St. Louis, MO 4
Purpose/Objective(s): The Quality Research in Radiation Oncology (QRRO) GU and eData committees established a task group to prospectively demonstrate remote de-identification and common aggregation of prostate brachytherapy treatment plans for comparative quality assessment from a representative cross section of United States radiation oncology facilities. Materials/Methods: Seventy prostate brachytherapy datasets consisting of DICOM CT images, RT Structure Set, and RT Dose files extracted from a variety of treatment planning systems (TPS), were remotely de-identified and submitted from 16 US sites to a data aggregation control center at the ITC. The de-identified CT image files were separated and accessed by the reference expert center where new structure and dose files were created in a single TPS. The new files were then uploaded, registered to the originally submitted treatment plans, and used as the benchmark to compare the original structure and dose files and to assess quality. In 69 of 70 submitted datasets, submitted (S) and reference expert (R) dataset-pairs were successfully registered for analysis. Results: For 69 evaluable cases, spatial and dose-volume metrics were used to analyze S and R datasets. The spatial similarity of S and R prostate contours was assessed using Dice’s coefficient (avg. 0.837, SD 0.043). Dose-volume histograms for S and R contours were computed for both S and R dose distributions and used to assess the accuracy of submitted plans when compared to the reference expert. Average pD90 for prostate as percentage of prescription dose (PD) was 101.5, (SD 17.6); for S contours/doses, and 101.1 (sd18.5) for R contours/doses. The average pV100% and pV150% (% volumes of prostate receiving 100% and 150% PD) were 88.1 (SD 10.7) and 52.6 (SD 16.5), respectively for S contours/doses and 87.9 (SD 11.2) and 53.2 (SD 16.5) respectively for R contours/doses. Rectal pD2cc (min. dose to the hottest 2 cc as percentage of PD) for R contours/doses was 66.6 (SD 20.3) for the entire rectum and 58.8 (SD 17.0) for rectum minus the volume within 5 mm of the prostate. Conclusions: This prospective project demonstrated the feasibility of remote de-identification, common aggregation, and comparative analysis of volumetric TP data for evaluating the quality of prostate brachytherapy seed plans. Tools and methods developed through the Advanced Technology Consortium were successfully adapted for this project to facilitate the export, submission, and dose-volume analysis of data. Export of datasets from TPS as DICOM was largely successful, but required manual effort for surveyors to include prescription and seed data due to imperfect interoperability. Acknowledgement: Supported by NCI Grants R01 CA65435 (QRRO) and U24 CA81647 (ATC) NCI grants. Author Disclosure: P.M. Devlin: None. M.J. Zelefsky: None. G.N. Cohen: None. P.L. Nguyen: None. C.L. Crozier: None. J. Owen: None. C.M. Rose: None. J. Wilson: None. W.R. Bosch: None.
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Improving Prostate Brachytherapy Quality Assurance with MRI-based Sector Analysis in a Phase II Prospective Trial
A. P. Brown, T. J. Pugh, D. A. Swanson, R. J. Kudchadker, T. L. Bruno, E. N. Christensen, S. J. Frank MD Anderson Cancer Center, Houston, TX Purpose/Objective(s): Sector analysis is a clinical tool that can be used in the post-implant quality assurance process for prostate brachytherapy by calculating the dose delivered to different sectors within the prostate. Each sector can be correlated to biopsy results for individual patients. However, sector analysis has not been translated to clinical practice, in part due to poor anatomic visualization of the prostate base and apex on post-implant CT scans. The purpose of this study is to evaluate MRI-based sector analysis as a method to improve the post-implant quality assurance process of brachytherapy. Materials/Methods: Fifty intermediate-risk prostate cancer patients received I-125 brachytherapy as monotherapy in a prospective Phase II clinical trial. Day 30 post-implant MRI and CT scans were fused to optimize prostate visualization on MRI and seed identification on CT. Sector analysis was performed by dividing the prostate into 6 sectors that can be correlated to pathology results, specifically the right and left portions of the base, mid-gland and apex. Sector analysis dosimetry (V100, D90, and D100) was then performed on each sector for the ultrasound (US) treatment plan, and then compared to post-implant sector analysis dosimetry calculated using CT alone and MRI-CT fusion. Results: Twenty-four of 50 patients had positive biopsies at the base, 34 at the mid gland, and 27 at the apex. Post-implant doses for the whole prostate using MRI-CT fusion (V100 = 91.3% and D90 = 152.9 Gy) were significantly lower than both US planned doses (100%; 188.9 Gy), and doses calculated using CT alone (98.5%; 183.6 Gy) (p \ 0.0001). Sector analysis showed that the area of the prostate most responsible for the discrepancy in dose delivered was at the prostate base, where the dose from MRI-CT fusion (V100 = 79% and D90 = 130 Gy) was significantly lower than both US planned (100%; 200 Gy) and post-implant CT alone (96%; 170 Gy) (p \ 0.0001). The minimum dose delivered (D100) to the base on MRI-CT fusion (mean = 86 Gy) was significantly lower than US planned doses (157 Gy) and had a wider range (35 – 151 Gy vs. 133 – 178 respectively) (p \ 0.0001). Conclusions: MRI-based sector analysis provides a comprehensive and accurate assessment of the dose delivered to specified regions within the prostate following brachytherapy. Standard post-implant dosimetry using CT alone overestimated the dose delivered to the prostate. Sector analysis further revealed a 35% mean reduction of the planned dose at the base, where 48% of patients had biopsy-proven cancer. MRI-based sector analysis can be used to correlate the dose delivered with pathology results, outcomes, and toxicity to improve quality assurance and optimize treatment delivery in prostate brachytherapy. Author Disclosure: A.P. Brown: None. T.J. Pugh: None. D.A. Swanson: None. R.J. Kudchadker: None. T.L. Bruno: None. E.N. Christensen: None. S.J. Frank: None.
1111
Secure Web-based Remote Quality Assessment of Prostate Brachytherapy Treatment Plans for a Multiinstitutional Patterns of Care/QRRO Survey: A Proof of Principle Study
P. M. Devlin1, M. J. Zelefsky2, G. N. Cohen3, P. L. Nguyen1, C. L. Crozier4, J. Owen4, C. M. Rose5, J. Wilson6, W. R. Bosch7 1
Brigham & Women’s Hospital, Boston, MA, 2Memorial Sloan Kettering Cancer Center, New York, NY, 3MSKCC, New York, NY, American College of Radiology, Philadelphia, PA, 5QRRO, Los Angeles, CA, 6Medical College of Wisconsin, Milwaukee, WI, 7 ITC, St. Louis, MO 4
Purpose/Objective(s): The Quality Research in Radiation Oncology (QRRO) GU and eData committees established a task group to prospectively demonstrate remote de-identification and common aggregation of prostate brachytherapy treatment plans for comparative quality assessment from a representative cross section of United States radiation oncology facilities. Materials/Methods: Seventy prostate brachytherapy datasets consisting of DICOM CT images, RT Structure Set, and RT Dose files extracted from a variety of treatment planning systems (TPS), were remotely de-identified and submitted from 16 US sites to a data aggregation control center at the ITC. The de-identified CT image files were separated and accessed by the reference expert center where new structure and dose files were created in a single TPS. The new files were then uploaded, registered to the originally submitted treatment plans, and used as the benchmark to compare the original structure and dose files and to assess quality. In 69 of 70 submitted datasets, submitted (S) and reference expert (R) dataset-pairs were successfully registered for analysis. Results: For 69 evaluable cases, spatial and dose-volume metrics were used to analyze S and R datasets. The spatial similarity of S and R prostate contours was assessed using Dice’s coefficient (avg. 0.837, SD 0.043). Dose-volume histograms for S and R contours were computed for both S and R dose distributions and used to assess the accuracy of submitted plans when compared to the reference expert. Average pD90 for prostate as percentage of prescription dose (PD) was 101.5, (SD 17.6); for S contours/doses, and 101.1 (sd18.5) for R contours/doses. The average pV100% and pV150% (% volumes of prostate receiving 100% and 150% PD) were 88.1 (SD 10.7) and 52.6 (SD 16.5), respectively for S contours/doses and 87.9 (SD 11.2) and 53.2 (SD 16.5) respectively for R contours/doses. Rectal pD2cc (min. dose to the hottest 2 cc as percentage of PD) for R contours/doses was 66.6 (SD 20.3) for the entire rectum and 58.8 (SD 17.0) for rectum minus the volume within 5 mm of the prostate. Conclusions: This prospective project demonstrated the feasibility of remote de-identification, common aggregation, and comparative analysis of volumetric TP data for evaluating the quality of prostate brachytherapy seed plans. Tools and methods developed through the Advanced Technology Consortium were successfully adapted for this project to facilitate the export, submission, and dose-volume analysis of data. Export of datasets from TPS as DICOM was largely successful, but required manual effort for surveyors to include prescription and seed data due to imperfect interoperability. Acknowledgement: Supported by NCI Grants R01 CA65435 (QRRO) and U24 CA81647 (ATC) NCI grants. Author Disclosure: P.M. Devlin: None. M.J. Zelefsky: None. G.N. Cohen: None. P.L. Nguyen: None. C.L. Crozier: None. J. Owen: None. C.M. Rose: None. J. Wilson: None. W.R. Bosch: None.
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