Commissioning of Elekta InfinityTM 6 MV flattening filter-free using Monte Carlo simulation

Commissioning a simulation model of the linear accelerator (Linac) in radiotherapy needs to be done to validate the dose distribution accuracy. For this purpose, the Monte Carlo simulation method is commonly employed, and it involves using the EGSnrc software. This software consists of BEAMnrc for modeling Linac and DOSXYZnrc for calculating dose distribution in a water phantom. This study used Monte Carlo simulation to commission the Linac Flattening Filter-Free (FFF) Elekta InfinityTM 6 MV photon mode. The commissioning results show that the simulated dose distribution satisfied the acceptance criteria of simulation results using initial electron energy of 6.9 MeV at 5 x 5, 10 x 10, and 20 x 20 cm2 field sizes with average local difference of percent depth dose (PDD) of about 2.99%. The dose and dmax increasedwith higher initial electron energy increased, while percentage depth dose (PDD) decreased at smaller field sizes. At larger field sizes, the dose profile widened and the PDD Linac FFF decreased more significantly than PDD Linac Flattening Filter (FF). Additionally, both exhibited dif-ferences in the uniformity of dose values in the umbra area. The surface dose for a 10 x 10 cm2 field size was 25.2% and 34.4% for both 6 MV-FF and 6 MV-FFF, respectively.

Automated summary

Commissioning of the Linac Flattening Filter-Free (FFF) Elekta InfinityTM 6 MV photon mode was performed using Monte Carlo simulation, showing that the simulated dose distribution satisfied acceptance criteria with an average local difference of 2.99% PDD. Dose and Dmax increased with higher initial electron energy, while PDD decreased at smaller field sizes. The dose profile widened and the PDD of Linac FFF decreased more significantly than Linac FF at larger field sizes, with both exhibiting differences in dose uniformity in the umbra area.