Feasibility of dose accumulation for assessing treatment-related side effects in MR-guided abdominal SABR: A single-institution study.

Abstract

BackgroundDaily adaptive magnetic resonance (MR)-guided treatment changes delivered dose distributions, making cumulative dose uncertain. This work assessed the feasibility of exploring potential relationships between side effects and accumulated dose (AD) in MR-guided stereotactic ablative radiotherapy (SABR) for liver and pancreatic cancers. Using deformable image registration (DIR), AD to abdominal organs at risk (OARs) were estimated and potential relationships with observed side effects explored.MethodsForty-one patients treated with 5-fraction MR-guided SABR to primary or metastatic pancreatic and liver tumours were retrospectively included. Daily adapted plans were deformably mapped and summed to estimate AD. Differences between accumulated and planned dose were assessed. Changes in clinician-reported symptoms collected at baseline, 3, and 6 months were analysed. Associations between AD and symptoms were assessed using Spearman's rank test.ResultsMost AD metrics were lower than planned for gastrointestinal OARs, reflecting potential differences from delivered ATS plans, with significant reductions in duodenum and large bowel D0.5cc and D10cc (p s 0.4-0.5, p ConclusionExploring potential relationships between DIR-based accumulated OAR dose and side effects was feasible. Preliminary relationships between accumulated OAR dose and side effects were observed; however, further work in larger studies is warranted before these findings can be used to personalise treatment in the future.