Calcium-based TLD materials for radiation applications

Abstract

This study focused on radiation interaction parameters of four compounds of calcium which are the most common types of thermoluminescence dosimetry (TLD). Firstly, the mass attenuation coefficients (MAC, mu/rho) and effective atomic numbers (Z(eff)) of calcium based-TLD materials such as CaSO4, CaF2, Ca5F(PO4)(3) and CaCO3 were measured in the energy region 121.87-1408.01 keV. The values of MACs and Z(eff)s of CaSO4, CaF2, Ca5F (PO4)(3) and CaCO3 were then theoretically calculated at same photon energies. Good agreements were observed between the experimental and theoretical results for MAC and Z(eff) values (diff. <= 8.17%). In addition, the mass energy absorption coefficients, Kerma relative to soft tissues, equivalent atomic number (Z(eq)), and buildup factors (energy absorption and exposure buildup factors; EABF, EBF) were theoretically calculated in the energy region 0.08-2 MeV. The results displayed significant changes in equivalent atomic number, such that these values increased with the increasing energy and after 1 MeV it generally decreased. CaCO3 was finally found the best tissue equivalent material because of fact that the values of Kerma and Z(eff) ratios were nearest to unity (1) among calcium-based TLD materials at the studied energies.