Calculation and correction of the eye-lens dosemeter response at non-calibration photon energies

Abstract

In this article, the calibration curve of GR-200 TLDs (Thermo-Luminescent Dosemeters) as eye-lens dosemeters was experimentally generated in a standard $^{137}$Cs field. Subsequently, the energy and angular responses of TLDs positioned on the ISO cylindrical head phantom were calculated using Geant4 simulation toolkit. The results indicated that the response at energies below 200 keV deviates by $\sim$1.85 times compared with that at 662 keV. Furthermore, the responses to 70 kVp and 120 kVp X-rays used in angiography were 1.65 and 1.61 times greater, respectively. The responses to these X-rays were also found to be independent of the irradiation angle between 0$^{\circ }$ and 75$^{\circ }$, with a maximum deviation of 28%. Finally, a correction method based on the relative energy response of GR-200 TLDs was proposed to adjust their response at photon energies or spectra different from the calibration field, thereby improving the accuracy of H$_{p}$(3) assessment.