(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: Field independent phase-space (PS) files are available for TrueBeam (TB) machine. This study aims to verify and validate the accuracy of these PS files for photon beams, against measurement.
Methods: The PS files are used as input in VirtuaLinac (VL), utilising Monte Carlo (MC) code Geant 4. MC simulations are scored in a phantom of 2x2x1 mm3 using 3x3, 10x10, 20x20 and 30x30 cm2 field sizes (FS). The particles included in the PS files are carried forward towards the field dependent section of the VL and in due course to the water phantom. Percentage Depth Dose (PDD) and profiles at dmax for photon energies (6MV and 6MV FFF) are measured and compared with simulation.
Results: PDD analysis revealed that the dose difference increased with increase in depth and slightly increases with FS. Average dose difference for 3x3, 10x10, 20x20 cm2 FS for both 6MV and 6MV FFF are ~ 2%. For a FS of 30x30cm2, the dose difference increased towards 3%. For profiles, dose difference inside the field is within 2%, and the value increased to 3 to 5% at the edges for both 6MV and 6MV FFF energies.
Conclusion: The agreement between MC and measurements proved that the field-independent PS files for TB, 6MV, and 6MV FFF beams, can be used as radiation sources for MC simulations resulting in accurate dose estimation. Also, the entire study is performed using VL, and hence can prove that this cloud solution is an accurate tool for simulating TB head.
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