Comprehensive validation of halcyon 2.0 plans and the implementation of patient specific QA with multiple detector platforms.

Purpose: To perform a comprehensive validation of plans generated on a preconfigured Halcyon 2.0 with preloaded beam model, including evaluations of new features and implementing the patient specific quality assurance (PSQA) process with multiple detectors.

Methods: A total of 56 plans were generated in Eclipse V15.6 (Varian Medical System) with a preconfigured Halcyon treatment machine. Ten plans were developed via the AAPM TG-119 test suite with both IMRT and VMAT techniques. 34 clinically treated plans using C-arm LINAC from 24 patients were replanned on Halcyon using IMRT or VMAT techniques for a variety of sites including: brain, head and neck, lung, breast, abdomen, and pelvis. Six of those plans were breast VMAT plans utilizing the extended treatment field technique available with Halcyon 2.0. The dynamically flattened beam (DFB), another new feature on Halcyon 2.0, was also used for an AP/PA spine and four field box pelvis, as well as ten 3D breast plans. All 56 plans were measured with an ion chamber (IC), film, portal dosimetry (PD), ArcCHECK, and Delta4. Tolerance and action limits were calculated and compared to the recommendations of TG-218.

Results: TG-119 IC and film confidence limits met those set by the task group, except for IMRT target point dose. Forty-four of 46 clinical plans were within 3% for IC measurements. Average gamma passing rates with 3% dose difference and 2mm distance-to-agreement for IMRT/VMAT plans were: Film - 96.8%, PD - 99.9%, ArcCHECK - 99.1%, and Delta4 - 99.2%. Calculated action limits were: Film - 86.3%, PD - 98.4%, ArcCHECK - 96.1%, and Delta4 - 95.7%. Extended treatment field technique was fully validated and 3D plans with DFB had similar results to IMRT/VMAT plans.

Conclusion: Halcyon plan deliveries were verified with multiple measurement devices. New features of Halcyon 2.0 were also validated. Traditional PSQA techniques and process specific tolerance and action limits were successfully implemented.