Shielding performance of multi-metal nanoparticle composites for diagnostic radiology: an MCNPX and Geant4 study

Abstract

Lead-free polymer composite shields are used in diagnostic radiology to protect patients from unnecessary radiation exposure. This study aimed to examine and introduce the radiation-shielding properties of single- and multi-metal nanoparticle (NP)-based composites containing Bi, W, and Sn using Geant4, MCNPX, and XCom for radiological applications. The mass attenuation coefficients and effective atomic numbers of single- and multi-metal NP-loaded polymer composites were calculated using the Geant4 and MCNPX simulation codes for X-ray energies of 20-140 keV. The nano-sized fillers inside the polydimethylsiloxane (PDMS:C(2)H(6)SiO) matrix included W (K = 69.5 keV), Bi (K = 90.5 keV), and Sn (K = 29.20 keV). For single-metal shields, one filler was used, while in multi-metal shields, two fillers were required. The MCNPX and Geant4 simulation results were compared with the XCom results. The multi-metal NP composites exhibited higher attenuation over a larger energy range owing to their attenuation windows. In addition, Bi(2)O(3) + WO(3) NPs showed a 39 higher attenuation at 100-140 keV, and that of Bi(2)O(3) + SnO(2) NPs was higher at 40-60 keV. Meanwhile, the WO(3) + SnO(2) NPs exhibited lower attenuation. The difference between the results obtained using Geant4 and XCom was less than 2, because these codes have similar simulation structures. The results show that the shielding performance of the Bi(2)O(3) + WO(3) filler is better than that of the other single- and multi-metal fillers. In addition, it was found that the Geant4 code was more accurate for simulating radiation composites.