Theoretical and Monte Carlo-based Kerma factor evaluation for various thermoluminescence (TL) dosimetry materials over a wide range of photon energies

Thermoluminescence dosimetry is one of the most common methods for personal and environmental dose monitoring. Having the Kerma factors related to the different TLD materials is beneficial for fluence to the dose conversion dosimetry method. In this regard, Kerma factors for various TLD materials over a wide range of photon energies (1 keV-20 MeV) are obtained by theoretical and Monte Carlo simulation approaches. Fifteen types of TLD materials were evaluated in the current study. Analytical Kerma factors were calculated by tabulated mass energy-absorption coefficients at different photon energies, while simulated Kerma factors were obtained by MCNPX Monte Carlo code. The accordance of obtained data by two considered approaches was evaluated through a significance statistical test. The results of both approaches showed compatible Kerma factors for all studied TLD materials (P-value >= 0.8). Low effective atomic number TLD materials such as LiF, Li2B4O7, and MgB4O7 had the closest Kerma factor values to those of soft tissue at different photon energies. On the other hand, the Kerma factors related to the high effective atomic number materials including BaSO4, C4H6BaO4, and CdSO4 considerably deviate from those of soft tissue. Based on the obtained results, it can be concluded that the Monte Carlo approach is a reliable method for determining the Kerma factor value at different photon energies, especially at photon energies higher than 20 MeV where the required data for analytical Kerma factor calculation are not available. Li2B4O7 can well mimic the soft tissue response for personal dose monitoring through thermoluminescence dosimetry.