Abstract ID: 142 Monte Carlo modeling of Varian TrueBeam with Geant4-based VirtuaLinac and comparison to experiments

Monte Carlo simulations can provide powerful insight into the physical phenomena and geometrical interactions of linear accelerator beams. This insight can be used to understand the phenomena that govern the beam characteristic and, for instance, to guide the development of treatment planning systems. In this study, we use the VirtuaLinac, a cloud-based application to model the treatment head of the Varian TrueBeam linear accelerator. VirtuaLinac implements the treatment head geometry into the Monte Carlo code Geant4, which is then utilized to provide the physics and numerical engine for the simulations. We consider both open fields and fields limited by multi-leaf collimators and compute the dose deposited in a water phantom. We then compare the simulation results with experimental measurements. The simulated data are also used to extract some of the characteristics of the multi-leaf collimators and to evaluate their impact on the beam properties and the dose distribution.