Commissioning of a synchrotron-based proton beam therapy system for use with a Monte Carlo treatment planning system

This work tackles the commissioning and validation of a novel combination synchrotron-based proton beam therapy system (Hitachi, Ltd.) for use with Monte Carlo treatment planning (TPS). Four crucial aspects in this configuration have been investigated: (1) Carlo-based correction performed by TPS to measured integrated depth-dose curves (IDD), (2) circular spot modelling single Gaussian function characterize synchrotron physical spot, which is elliptical, (3) range shifter that enables using only one set measurements open beams, (4) dose calculation model small fields. Integrated were PTW Bragg peak chamber corrected, model, account energy absorbed outside detector. The elliptical was IBA Lynx scintillator, EBT3 films microDiamond. accuracy (RayStation, RaySearch Laboratories) at assessed. validated spread-out (SOBP) We took single-point doses several depths through central axis Farmer chamber, fields between 2 × 2cm 30 30cm. checked range-shifter from open-beam data. tested clinical cases film an ionization array (IBA Matrix). Sigma differences spots fitted 2D images 1D profiles models below 0.22 mm. Differences SOBP points calculations all 5 30cm 2.3%. Smaller had larger differences: up 3.8% field. Mean along generally 1%. 2.4%. Gamma test (3%, 3 mm) results above 95% Matrix film. Approaches beams validated. Dose values demonstrate accurate IDDs. Elliptical can be successfully modelled Gaussian, patient used A double-Gaussian improve small-field calculations. approach, reduces time, adequate.