SU‐D‐BRB‐07: Use of Knowledge‐Based Planning to Evaluate the Need for Motion Management in Lung SBRT

Abstract

Purpose:The planning margins necessary to safely treat targets in the lung can be reduced depending upon the use of gating or abdominal compression to manage respiratory motion, but these may be uncomfortable for the patient, involve expensive equipment, or increase the length of each treatment fraction. The goal of this project is to use knowledge‐based‐planning (KBP) to evaluate which patients may benefit most from motion management.Methods:The Varian RapidPlan” KBP module was used to estimate doses for VMAT SBRT lung treatment plans with different planning margins corresponding to 1) standard lung setup (1.0 cm radial margin, 2.0 cm S‐I margin), 2) daily IGRT (0.7 cm radial 1.5 cm S‐I), 3) daily IGRT with motion management (0.5 cm radial, 1.0 cm S‐I). The estimated doses were then compared with treatment plan doses (AAA dose calculation) generated using the RapidPlan™ optimization constraints. Treatment plan doses were then compared against RTOG protocol dose limits for organs at risk.Results:The OAR doses were within or below the estimated range generated by the KBP system in 100% of plans. With standard margins, only 10% of the plans were able to meet all RTOG dose goals, compared with 75% of plans with IGRT margins. All plans were able to meet RTOG dose guidelines with motion management. The DVH estimation was able to correctly identify 100% of the plans in which one or more OAR doses exceeded RTOG guidelines. Also, the dose estimates correctly identified 88% of individual OAR doses exceeding RTOG guidelines.Conclusion:The KBP system was able to accurately predict the achievable doses in treatment plans, and predict patients in which RTOG dose guidelines would be exceeded. The system may be a useful tool in identifying patients where motion management may be necessary for SBRT treatment.This work was supported by Varian Medical Systems.