Program Information
Optimization of Treatment Planning Workflow and Tumor Coverage During Daily Adaptive MR-G-RT of Pancreatic Cancer
S Olberg1*, O Green2 , B Cai3 , D Yang4 , V Rodriguez5 , H Zhang6 , P Parikh7 , S Mutic8 , J Park9 , (1) Missouri University of Science and Technology, Rolla, MO,(2) Washington University School of Medicine, St. Louis, MO, (3) Washington University School of Medicine, St. Louis, MO, (4) Washington University in St Louis, St Louis, MO, (5) Washington University School of Medicine, St. Louis, MO, (6) Washington University School of Medicine, St. Louis, MO, (7) Washington Univ. School of Medicine, Saint Louis, MO, (8) Washington University in St Louis, St Louis, MO, (9) Washington University in St. Louis, St. Louis, MO
Presentations
SU-K-601-12 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: 601
Purpose: To optimize the efficiency of the adaptive treatment planning workflow while achieving the maximum tumor-dose coverage in pancreatic cancer patients undergoing daily adaptive MR-g-RT.
Methods: In daily adaptive MR-g-RT, the objective function constructed at the simulation plan is used for plan re-optimization throughout the course of treatment. In this study, we have constructed the initial objective functions using two methods: 1) the conventional method that handles all OARs separately and 2) OAR grouping. Using OAR grouping, a combined OAR structure that encompasses the portions of the stomach, duodenum, small bowel, and large bowel within 3 cm of the PTV was created. These two sets of objective functions were optimized such that the coverages were comparable and individual OAR constraints were not violated. The two adaptive plans created at each successive fraction were compared in terms of D100 and D95 coverage over the PTV, the range between D100 and D95 coverage, and D95 coverage of the CTV.
Results: Plan quality and coverage was enhanced across all fractions using OAR grouping. D100 coverage of the PTV improved by an average of 16.82%, while D95 coverage improved by an average of 6.05% and 4.61% over an initial and optimized PTV respectively. Differences between D100 and D95 coverage were on average 2.56 times smaller using the proposed method compared to the conventional plans. Finally, D95 coverage of the CTV was improved by an average of 2.18% when OAR grouping is utilized over conventional methods.
Conclusion: OAR grouping offers the potential for substantial time savings by enhancing the efficiency of the MR-g-RT adaptive treatment planning workflow and demonstrates improved plan quality compared to clinically delivered plans. These improvements have special relevance to hard-to-treat pancreatic cancer cases, representing a means to more effective treatment of these cases.
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