Monte Carlo simulation of scattered and thermal photoneutron fluences inside a radiotherapy room.

In this work, the behaviour of scattered and thermal photoneutron fluences in a radiotherapy treatment room was investigated by means of Monte Carlo simulation. The MCNP code was used to study the dependence of these neutron fluences on room design, room area and the effect of neutron moderator materials placed on the room walls. The results of the investigation showed a poor agreement between the simulations and empirical approximations, suggesting that the formulae found in the literature can underestimate the neutron flux inside a radiotherapy room.