Exhibit Hall | Forum 2
Purpose: We proposed an online GPU-accelerated Monte-Carlo (MC)-based adaptive radiation therapy (ART) workflow for pencil-beam-scanning (PBS) proton therapy to address inter-fraction anatomical changes in PBS.
Methods: A four-step workflow of online PBS ART was developed based on our in-house GPU-accelerated MC-based PBS treatment planning system. Step one conducts deformable image registration (DIR) and DIR-based contour propagations to derive the new structure set in the verification CT (vCT). Step two performs forward dose calculation on vCT (verification plan). Step three triggers a plan re-optimization based on the verification plan evaluation. Step four involves a two-stage (before (comparing with an independent MC code, MCsquare) and after (using the log file generated during the plan delivery) delivery) patient-specific quality assurance (PSQA) of the re-optimized plan with 3D Gamma analysis. Plan robustness evaluation will be done for both verification plan and re-optimized plan. A commercial software, ClearCheckTM, is integrated into the workflow to evaluate plan quality. Three patients with three different disease sites were chosen to evaluate the feasibility of the online PBS ART workflow.
Results: For all three patients, the propagated contours had good volume conformity but sub-optimal boundary coincidence for organs-at-risk. The verification plan showed significant degradation of the target coverage. Re-optimizations improved plan quality to be clinically acceptable. 3D Gamma analyses in PSQA confirmed the plan dose accuracy (>98.5% passing rates with 2mm/2%/10%). The average total time for the workflow was around 858 seconds, excluding possible manual intervention.
Conclusion: The proposed online PBS ART workflow was demonstrated to be efficient and effective by generating a re-plan that significantly improved plan quality.
Not Applicable / None Entered.
TH- External Beam- Particle/high LET therapy: Proton therapy – adaptive therapy