Development and In Silico Validation of an Online Adaptive Workflow for Proton Therapy With an In-Room...

Development and validation of an online adaptive proton therapy workflow for clinical use.

A script-based online adaptive proton therapy workflow was developed in a graphics processing unit (GPU)-accelerated treatment planning system to automate plan adaptation using traditional computed tomography (CT) images acquired on an in-room CT-on-rails. Monte Carlo-based secondary dose calculation and log file analysis of machine parameters were integrated into the workflow to provide quality assurance (QA) before and after delivery of the adapted treatment plan. In silico retrospective testing was performed on 10 previously treated pelvic patients to validate the workflow; a total of 50 fractions were included in this study. The fidelity of adapted dose distributions, time required for the in silico workflow, and QA results were recorded and analyzed.

The median (interquartile range) time required for this workflow was 61.9 (12.2) minutes, demonstrating technical feasibility for online adaptation. Of the 50 evaluated fractions, 15 (30%) showed clinically meaningful improvements in sparing of the highest-priority organ-at-risk using the adaptive plans (P_A), and 8 (16%) showed improved target coverage relative to the scheduled plan. Both Monte Carlo-based secondary dose checks and log file-based machine QA were within institutional tolerance criteria, confirming the dosimetric accuracy and delivery fidelity of the workflow.

A fully integrated, QA-embedded online adaptive proton therapy workflow using in-room CT-on-rails imaging was developed and validated in silico on a clinical proton beamline. The workflow demonstrated clinically acceptable treatment times and reliable dosimetric accuracy and provided measurable benefits in organ-at-risk sparing and target coverage for a substantial subset of fractions. These results support the readiness of this workflow for clinical use.