Monte Carlo commissioning of 6 MV photon beam of varian linear accelerator installed at INOR

This study aims at the Monte Carlo (MC) commissioning of Varian Clinac 2100C medical linear accelerator (LINAC) for 6 MV photon beam. The MC-based EGSnrc user sub codes BEAMnrc and DOSXYZnrc were used for accelerator head modeling and dose calculations in water phantom respectively. As the first step in the commissioning of LINAC, optimum incident electron beam energy was investigated. For that purpose, lateral beam profiles (at different depths) and percentage depth dose curves were acquired for different field sizes (5 ×5, 10 × 10, 20 × 20 and 30 × 30 cm 2 ). By the comparison of simulated and measured dose profiles, the optimum incident electron beam energy was found to be 5.8 MeV using x 2 test. Lateral beam profiles and depth dose curves agreed well with reference data. However, lateral beam profiles are found to be more sensitive than depth doses to changes in incident electron beam energy.