Evaluation of the impact of PL/hBN and PL/B4C on the neutron leakage generated by the LINAC in the treatment room

Abstract

In this study, the maximal reduction of neutron leakage into the treatment room and bunker walls was evaluated by placing three stratified layers of PL/hBN and PL/B4C at distinct spatial coordinates within a medical linear accelerator facility. Simulations were conducted using the MCNPX code, focusing on "Photon flux per therapeutic X-ray dose" and "Neutron leakage and neutron density per therapeutic X-ray dose." The results indicated that adding PL/hBN and PL/B4C layers achieves the desired dose with a lower photon flux. The PL/hBN layer in a better proportion reduced flux compared to the PL/B4C layer. It was found that the PL/hBN layer can reduce neutron leakage and density in the air by up to 60.43 % and 50.08 %, respectively, while the PL/B4C layer achieved reductions of 44.32 % and 34.86 %. Additionally, reductions in neutron leakage and density within the bunker walls reached 95.61 % and 86.22 % with the PL/hBN shield, and up to 80.46 % and 70.59 % with the PL/B4C shield. These findings underscore the effectiveness of these layered neutron shielding measures in reducing neutron populations within the treatment room air and enhancing bunker protection.