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Clinical Commissioning of the Pinnacle Proton Dose Engine for the Mevion S250 Delivery System

T Willoughby

T Willoughby*, O Zeidan , UF Health Cancer Center at Orlando Health, Orlando, FL


SU-I-GPD-T-129 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To report on the first clinical commission of a new double scattering calculations algorithm proton therapy.

Methods: We report the first commissioning of Pinnacle (Philips Medical) pencil-beam proton algorithm for the Mevion S250 double-scattering system. Pinnacle commissioning required a relatively short list of in-air and in-water data to model the span of ranges and SOBPs offered by the system. The module does not model details or geometries of the double-scattering hardware. All data was acquired using PTW 3D water scanning system with small volume or parallel-plate chambers. Air scans included PDD, full profiles, and half-beam profiles for several ranges. Water scans included pristine peak PDD, SOBP, and profiles for several ranges.

Results: The physics module in Pinnacle created a linear fit to air scans for Virtual SAD, Effective SAD, and Virtual Source sizes. The Analytical Approximation Model (Bortfeld 1997) was used to fit the pristine Bragg peaks for each range. The SOBP was created by data fitting the number and weight of pristine peaks fit measured data. Verification scans of profiles and SOBPs were used to validate the beam model. Test plans were created to evaluate films along the beam path for various ranges and modulations in homogenous phantom. Axial dose planes at various depths were measured using the MatriXX (IBA) 2D array and compared to the treatment plans. Overall, the agreement between model and verification data was within +-1mm in range and 1-3% dose difference everywhere.

Conclusion: We report on the first commissioning of the Pinnacle proton dose algorithm. Because of the unique construction of the beam model which is based solely on measured data without specific details of machine components, this simplified approach allows for shorted time to commission the planning system with fewer scans.

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