Program Information
Evaluation of a Ring-Mounted Compensator IMRT System for Efficient and Cost-Effective Radiotherapy in Low- and Middle-Income Countries
Daniel L Smith1*, Nicholas Fong1, Jonathon Van Schelt1, Patricia Sponseller1, Adam Shulman2, Derek Brown3, K Govindarajan4, Eric Ford1 1 University of Washington Medical Center, Seattle, WA, 2 Radiating Hope, Midvale, UT, 3 University of California, San Diego, La Jolla, CA, 4 PSG Hospital, Coimbatore, India
Presentations
TH-CD-708-2 (Thursday, August 3, 2017) 10:00 AM - 12:00 PM Room: 708
Purpose: Cancer is a major public health challenge in low- and middle-income countries (LMICs). Access to radiation therapy, a critical component to cancer care, is severely limited in LMICs due to economic challenges and difficulty translating technologies to resource-limited settings. We are developing a novel compensator-based IMRT system that is efficient and low-maintenance, which could be used with either a linear accelerator or a Cobalt-60 machine to deliver cost-effective treatment in LMICs. The purpose of this study is to examine the feasibility of this system through a plan quality analysis using linear accelerator-based IMRT as a benchmark.
Methods: We commissioned Cobalt-60 compensator-based machine models in the Pinnacle treatment planning system and benchmarked the models against EGSnrc Monte Carlo simulations. We then generated five head & neck (H&N) and three gynecological plans using a nine-field geometry. We compared tumor coverage and organ-at-risk sparing to the 6 MV IMRT-MLC plans used clinically.
Results: Compensator-based Cobalt-60 machines yielded comparable plan quality to 6MV MLC-IMRT plans. In the H&N plans, the PTV D99, D2, and max cord doses were within 2% for all plans evaluated, though the mean parotid dose was 10% higher in the Cobalt-60 compensator plans (not significant). In gynecological plans the PTV D99, D2, and bladder D35 were within 2%, while the rectum D60 was 7% greater for the compensator plans (not significant). For Cobalt-60 compensator plans, source-to-compensator distance (53 vs. 63 cm) had no apparent impact on plan quality. Treatment times are <3 minutes, due to the efficient use of beam with compensators and the novel ring geometry proposed here.
Conclusion: Compensator-based Cobalt-60 IMRT showed similar plan quality to clinical 6MV MLC-IMRT with short treatment times, suggesting that compensator-based IMRT may be feasible in LMICs. A prototype system will be developed with commercial and clinical partners at an LMIC site.
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