PRIMO Monte Carlo validation of Elekta Synergy Platform linac at Davao Doctors Hospital for a 10 MV photon beam: PRIMO Monte Carlo validation of Elekta Synergy Platform linac at Davao Doctors Hospital for a 10 MV photon beam

Abstract

Using PRIMO Monte Carlo (MC) software package, 10 MV photons from an Elekta MLCi linac are simulated. To validate the MC model, the simulated beam data are benchmarked against measured data from an Elekta Synergy Platform linac at Davao Doctors Hospital [DDH] in the southern Philippines. This requires fine-tuning of the electron beam parameters namely; electron beam's initial energy, full-with-half-maximum (FWHM) of the energy, focal spot size FWHM and beam divergence. The fine-tuning process of linac with megavoltage photon beams involves optimization of the electron beam's initial energy and this optimized value is then input to subsequent simulations to reproduce the lateral beam profiles. The lowest gamma index passing criteria of 1%/1mm is used as determinant in finding the matching values of all beam parameters. The percentage depth dose (PDD) and lateral profile dose distributions are calculated for treatment field sizes of 5 × 5 cm2 and 20 × 20 cm2 at source-to-surface distance of 100 cm in a homogeneous phantom. The optimized beam configurations are then simulated at higher statistics to verify the good agreement with measurements.