Monte Carlo simulation of photoneutrons streaming inside radiotherapy treatment rooms as a function of gantry angles

This work describes Monte Carlo simulations of neutron production and the consequently transport inside the maze of a medical linear accelerator bunker, calculated as a function of the gantry angles. The choice of the radiotherapy equipment, subject of the study, was the Varian Clinac 2300 CD, operating at 18 MV. The general purpose Monte Carlo N-particle radiation transport code, MCNPX, was used in the simulations in order to compute the ambient dose equivalent, H∗(10), in six points in the maze region, varying the gantry angles in steps of 45°. The obtained results demonstrate a considerable ambient dose equivalent variation as a function of the linear medical accelerator gantry angles.