Monte Carlo modeling of HD120 multileaf collimator on Varian TrueBeam linear accelerator for verification of 6X and 6X FFF VMAT SABR treatment plans

摘要: A Monte Carlo (MC) validation of the vendor-supplied Varian TrueBeam 6 MV flattened (6X) phase-space file and first implementation Siebers-Keall MC MLC model as applied to HD120 (for 6X flat flattening filter-free (6X FFF) beams) are described. The is validated in context VMAT patient-specific quality assurance. commissioning process involves: 1) validating calculated open-field percentage depth doses (PDDs), profiles, output factors (OF), 2) adapting match new HD120-MLC geometry material composition, 3) determining absolute dose conversion factor for calculation, 4) this entire linac/MLC calculation verification clinical plans. PDDs beams agree with measured data within 2.0% field sizes ranging from 2 × 40 cm2. Measured profiles show agreement 50% width 80%–20% penumbra region 1.3 mm all square sizes. OFs cm2 fields measurement 1.6%. Verification SABR lung, liver, vertebra plans demonstrate that ion chamber 0.6% beam FFF beam. 3D gamma analysis demonstrates beam, > 99% voxels meet pass criteria (3%/3 mm). For 94% criteria. accelerator delivering can be modeled provide an independent This assurance tool has been used clinically verify over 140 16 treatment