Purpose: Varian Eclipse 16.1 includes the capability to create a proton RapidPlan (RP) model. We tested the feasibility of using RP for generating clinically appropriate pencil beam scanning head and neck treatment plans.
Methods: Twenty-six left, right, and bilateral head and neck cases treated at our center were used to create the RP proton model. Five of the cases that were used for training and two cases not included in the training set were re-planned with RP for model validation. The RP model was trained without optimization and ring structures. Additionally, the RP cases were run only once using the same beam arrangement as the clinical plan. The re-planned and dosimetrist-planned cases were blinded and evaluated by an academic radiation oncologist specializing in head and neck cancer and proton therapy.
Results: While the 7 RP model plans passed our institutional plan and dose criteria, the radiation oncologist preferred the dosimetrist planned case over the RP in all 7 cases. Five of the 7 RP plans were determined to be clinically appropriate and not meaningfully different than the clinical plan. Two RP plans were deemed to require minor edits; no RP plans were judged inappropriate or to require major edits. Dose homogeneity and conformity were identified as the primary distinctions between the planning methods.
Conclusion: While the RP cases were not chosen as the preferred final plan, the model has demonstrated significant potential as a consistent starting point for the dosimetry team. The RP model also offers substantial time savings as it does not require generation of optimization structures. The relatively minor issues noted by the radiation oncologist were parameters that can be added to the model or addressed by a dosimetrist on editing the RP. Additional investigation is warranted into the clinical role of this tool.
Funding Support, Disclosures, and Conflict of Interest: Author receives honorarium and consulting fees from Varian Medical Systems.
TH- External Beam- Particle/high LET therapy: Proton therapy – treatment planning/virtual clinical studies