Simulation of the 6 MV Elekta Synergy Platform linac photon beam using Geant4 Application for Tomographic Emission

The present work validates the Geant4 Application for Tomographic Emission Monte Carlo software for the simulation of a 6 MV photon beam given by Elekta Synergy Platform medical linear accelerator treatment head. The simulation includes the major components of the linear accelerator (LINAC) with multi-leaf collimator and a homogeneous water phantom. Calculations were performed for the photon beam with several treatment field sizes ranging from 5 cm x 5 cm to 30 cm x 30 cm at 100 cm distance from the source. The simulation was successfully validated by comparison with experimental distributions. Good agreement between simulations and measurements was observed, with dose differences of about 0.02% and 2.5% for depth doses and lateral dose profiles, respectively. This agreement was also emphasized by the KolmogorovuSmirnov goodness-of-fit test and by the gamma-index comparisons where more than 99% of the points for all simulations fulfill the quality assurance criteria of 2 mm/2%.