Photoneutron production and backscattering in high density concretes used for radiation therapy shielding

In the current study, the effect of high density concretes on photoneutron productions in radiation therapy was studied using Monte Carlo simulations. The photon and neutron spectra of an 18 MeV photon beam of the Varian linac head were used for all simulations. Ordinary and five high density concretes made of high density elements were simulated. The studied concretes consisted of Magnetite, Datolite-Galena, Magnetite--Steel, Limonite-Steel, and Serpentine. Our results showed that photoneutron production in these concretes strongly depends on their composition. It appears that the application of high density elements with higher probability for photoneutron production, such as Fe and Pb, increases the photoneutron production in concrete walls of radiation therapy bunkers. Further studies on the effect of concrete composition on photoneutrons in radiation therapy room are recommended. (C) 2011 Elsevier Ltd. All rights reserved.