Multi-nanoparticle-based composite for diagnostic X-ray shielding in computed tomography applications: a Monte Carlo study

While numerous studies have investigated the impact of various nanoparticles (NPs) in polymer matrices for radiation shielding, there is a notable gap in the literature regarding a comprehensive examination of both individual and combined selected NPs with functional polymers. This study aims to address this gap by systematically evaluating the synergistic potential of multiple high-Z NPs and specialized polymer matrices in radiation shielding design, particularly for computed tomography (CT) applications. A single and mixture range of NPs, including Gd₂O₃, Sm₂O₃, CeO₂, HfO₂, IrO₂, Bi₂O₃, and WO₃, were combined with polymers such as chlorinated polyvinyl chloride (CPVC), polychlorostyrene (PCS), polytrifluorochloroethylene (PTFCE), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polyvinylidene chloride (PVDC) which served as matrices. By means of Geant4 Monte Carlo simulations, the study assessed the shielding effectiveness of these nanocomposites at various X-ray energies (80, 100, 120, and 140 kVp). The results revealed that nanocomposites containing Sm₂O₃ and Gd₂O₃ exhibited superior X-ray attenuation at 80 and 100 kVp, while the HfO₂ nanocomposite demonstrated enhanced shielding at 120 and 140 kVp. Additionally, multi-filler nanocomposites with 30 wt% of Sm₂O₃ + HfO₂ (SmHf) and Gd₂O₃ + Bi₂O₃ (GdBi) exhibited improved performance at 80 and 140 kVp, respectively. Notably, the 30 wt% Gd₂O₃ + IrO₂ (GdIr) multi-filler nanocomposite outperformed others at 100 and 120 kVp. It is concluded that a combination of NPs with K-edge values close to the mean energy of the investigated X-ray spectra provide better shielding capabilities than single NPs, highlighting their potential for applications in radiation protection.