Gamma ray and neutron shielding capacity of and dosimetry of composite compounds with diagnostic and therapeutic energies

Purpose Ionizing radiation protection is one of the most fundamental research and application fields in reducing the absorbed dose of sensitive internal organs. The presence of lead as the first radiation shield with a series of good features, such as high density and having some flexibility, and a series of features such as toxicity, low physical and chemical stability and high weight has been thinking about replacing it for a long time. Therefore, in this research, we have investigated features of the ionizing radiation shielding of composite compounds without lead in the photon energy range of 15 keV to 15 MeV.
Methods To extract such features, it is necessary to use a computational method. In this research, we have done all our calculations based on the Geant4 tool based on the Monte Carlo method. This tool is a multi-purpose tool that can be used for particle transport calculations such as electrons, protons, neutrons, heavy charged particles and photons in different environments such as human tissues.
Results We have calculated mass attenuation coefficient (MAC) by using the Monte Carlo simulations such as Geant4 tool, XMuDat and XCOM codes. In the continuation of the investigation of the protection feature, four laboratory energies have been selected and investigated. In fact, the performance of shields against 60 keV, 662 keV and 1.2 MeV sources has been investigated. In this case, we have obtained the passing flux of photons, half-value layer (HVL), tenth-value layer (TVL) and mean free path (MFP). Then, the image of the passing photon flux of ²⁴¹Am (60 keV), ¹³⁷Cs (662 keV) and ⁶⁰Co (1.2 MeV) sources for a shielding sample is showed. Since the aim is to examine the overall protection characteristics of the samples, we have considered the source as a neutron-gamma mixture and made of ²⁵²Cf. In this case, the passing flux of photons and the ratio of neutrons passing through the shields are shown. In the continuation of the work, MIRD phantom has been used to check the performance of the shields in the amount of dose reached to the body and organs. In this case, for example, we have shown the received dose to the body and some organs as the ratio of the received dose in the presence of shields to the received dose in the absence of shields for the ¹³⁷Cs source.
Conclusions Quantitative results show that the selected compound is a suitable suggested compound for shielding ionizing rays in the range of diagnostic and therapeutic energies.