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WE‐DE‐201‐01: BEST IN PHYSICS (THERAPY): A Fast Multi‐Target Inverse Treatment Planning Strategy Optimizing Dosimetric Measures for High‐Dose‐Rate (HDR) Brachytherapy
Author(s) -
Guthier C,
Damato A,
Viswanathan A,
Hesser J,
Cormack R
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4957806
Subject(s) - brachytherapy , wilcoxon signed rank test , radiation treatment planning , dosimetry , medicine , nuclear medicine , radiation therapy , algorithm , medical physics , broyden–fletcher–goldfarb–shanno algorithm , radiology , computer science , mann–whitney u test , computer network , asynchronous communication
Purpose: Inverse treatment planning (ITP) for interstitial HDR brachytherapy of gynecologic cancers seeks to maximize coverage of the clinical target volumes (tumor and vagina) while respecting dose‐volume‐histogram related dosimetric measures (DMs) for organs at risk (OARs). Commercially available ITP tools do not support DM‐based planning because it is computationally too expensive to solve. In this study we present a novel approach that allows fast ITP for gynecologic cancers based on DMs for the first time. Methods: This novel strategy is an optimization model based on a smooth DM‐based objective function. The smooth approximation is achieved by utilizing a logistic function for the evaluation of DMs. The resulting nonconvex and constrained optimization problem is then optimized with a BFGS algorithm. The model was evaluated using the implant geometry extracted from 20 patient treatment plans under an IRB‐approved retrospective study. For each plan, the final DMs were evaluated and compared to the original clinical plans. The CTVs were the contoured tumor volume and the contoured surface of the vagina. Statistical significance was evaluated with a one‐sided paired Wilcoxon signed‐rank test. Results: As did the clinical plans, all generated plans fulfilled the defined DMs for OARs. The proposed strategy showed a statistically significant improvement (p<0.001) in coverage of the tumor and vagina, with absolute improvements of related DMs of (6.9 +/− 7.9)% and (28.2 +/− 12.0)%, respectively. This was achieved with a statistically significant (p<0.01) decrease of the high‐dose‐related DM for the tumor. The runtime of the optimization was (2.3 +/− 2.0) seconds. Conclusion: We demonstrated using clinical data that our novel approach allows rapid DM‐based optimization with improved coverage of CTVs with fewer hot spots. Being up to three orders of magnitude faster than the current clinical practice, the method dramatically shortens planning time.