  The present work is devoted to develop a computational model using the Gate
Monte Carlo software for the simulation of a 6MV photon beam given by Elekta
Synergy Platform medical linear accelerator treatment head. The model includes
the major components of the multileaf accelerator head and a homogeneous water
phantom. Calculations were performed for a photon beam with several treatment
fields size ranging from 5*5 cm2 to 30*30 cm2 at 100 cm distance from source.
The simulation is successfully validated by comparison with experimental
distributions measured at the Regional Hassan II Oncology Center. Good
agreement between simulations and measurements was observed, with dose
differences of about 1.6% and 1.8% for depth doses and lateral dose profiles,
respectively. The gamma index comparisons were also performed where more than
98% of the points for all simulations passed the standard quality assurance
criteria of 3mm/3%.
