Analysis of characteristics and validation of 6 MV photon beam produced by Elekta Synergy linear accelerator using EGSnrc Monte Carlo code

The most important step of the Monte Carlo (MC) dose calculation is the correct modelling of the radiation device. This study was aimed to determine the initial electron beam characteristics of the BEAMnrc model of 6 MV photon beam of Elekta Synergy IGRT System linear accelerator and to validate the simulation. For this purpose, EGSnrc/BEAMnrc/DOSXYZnrc Monte Carlo code were used for an accurate model of a 6 MV Elekta Synergy linac head. To analyze MC model, the dose distributions were calculated by EGSnrc/DOSXYZnrc simulation in a homogeneous water phantom. Then the results were compared with the measurements performed in the water phantom. In order to determine the mean energy and Full Width at Half Maximum (FWHM) suitable for the device in MC model, the Percentage of Depth Dose (PDD) and profile curves were compared for 10 × 10 cm2 field size. All data were analyzed using MATLAB. As a result, the mean energy of the device with the MC model was found to be compatible with the 6.2 MeV spectrum and 1 mm FWHM. For validation of MC model, PDD and profile curves for 5 × 5, 10 × 10, 15 × 15, 20 × 20 and 30 × 30 cm2 field sizes with 6.2 MeV spectrum and 1 mm FWHM were compared with water phantom measurement results. •Most accurate dose calculation method in radiotherapy is Monte Carlo Simulation.•The correct determination of the beam characteristics is the main difficulty in MC.•The beam characteristics must be determined correctly for accurate MC Simulation.•6.2 MeV initial beam energy and 1.0 mm FWHM were found for Elekta Synergy Linac.•The Elekta Synergy EGSnrc model was validated for different field sizes.