Polymer-based shielding with micro- and nanoparticles: An investigation to reduce photon and photoneutron contamination in a LINAC treatment room

The presence of photons and neutrons in the Linear Accelerator (LINAC) treatment room poses significant risks to both patients and staff. As a result, optimizing shielding materials to reduce photoneutron contamination has become a vital area of research. This study investigates the effectiveness of composite materials incorporating micro- and nanosized particles for shielding against photons and neutrons emitted by medical LINACs. The theoretical analysis was performed using the Monte Carlo N-Particle Transport Code (MCNP) version 6.1, employing two strategies to improve computational efficiency: firstly, replacing the photon source derived from emitted photons with a primary electron beam, and secondly, utilizing the Surface Source Write/Surface Source Read (SSW/SSR) cards. The phase space around the LINAC head was characterized and assessed at the isocenter both with and without shielding across 11 different materials. The impact of micro- and nanosized particles on the shielding's attenuation properties was analyzed, and the absorbed doses in a phantom were examined with and without microparticle fillers. Additionally, the composite matrix exhibited enhanced performance when combined with tungsten (W) and boron carbide fillers.