EPR dosimetric studies on strontium sulfate rods for possible use in radiotherapy

Abstract

Radiation-induced radicals in the crystals of strontium sulfate (SS) as rod dosimeters were studied using an electron paramagnetic resonance (EPR) spectrometer. Dosimetric studies were performed in the dose range of 0.5 to 25 Gy for the dosimeters to investigate their potential applications in radiotherapy (60Co γ-rays and high megavoltage X-ray with 6 and 15 MV). Additionally, the response of these dosimeters was compared to the response of alanine pellet dosimeters at the three-beam qualities. Irradiation of SS dosimeters produces five EPR signals, and their intensity increases linearly with increasing absorbed doses from 0.5 to 25 Gy. A peak of a splitting g-factor (g) = 2.01039 was selected for the present evaluations as it has a higher intensity. The change in response of SS rod dosimeters after irradiation does not exceed ±2% over six months, exhibiting good stability. The response of SS dosimeters increases with increasing the incident beam energy from 60Co gamma rays to 16 MV X-ray beam. For alanine dosimeters, a non-significant change is observed under these beam qualities. The response of SS dosimeter at 6 and 15 MV relative to a60Co beam quality increases by about 3.8% and 14.1%, respectively.Moreover, the response of the SS dosimeters increases 2.24% with increasing the dose rate from 100 to 400 cGy/min, while for the alanine dosimeters, the increase in response is less than 0.49%. Environmental factors (relative humidity levels of 0–76% and temperature degrees of 15–30 °C) have a slight impact on the response of SS rods during irradiation. The overall uncertainty of dose monitoring was reported to be ±4.02% (2σ, 95% confidence levels).