Energy and angular responses of the personal thermoluminescence dosimeter used in NSTRI

Accurate dosimetry is essential for radiation safety; however, energy and angular dependencies can introduce uncertainties in the dose-equivalent measurement. This study investigates energy and angular responses of the personal thermoluminescence dosimeter used at Nuclear Science and Technology Research Institute (NSTRI). Energy response from 20 keV to 11 MeV as well as angular response from zero to 90 degrees was calculated using the MCNPX code. Measurements were also conducted in 137Cs (reference) and 60Co fields. The calculated energy and angular responses agreed with the measured values within 11% margin. For single energies above 200 keV and X-ray spectra with the mean energies greater than 60 keV, the response deviated by no more than 11% from the 137Cs field. Additionally, for irradiation angles smaller than 60 degrees, the response deviated by no more than 6% from the zero angle. In these energies and angles, the dosimeter can determine the Hp(10) quantity with a total uncertainty of 12.5% accounting for both energy and angular uncertainties. Outside this ranges, the HP(10) value may be overestimated by up to 90% or underestimated by up to 76%, necessitating response correction.