Feasibility Study of the Radiophotoluminescent Glass Dosimeter for High-energy Electron Beams / 의학물리

ABSTRACT

Our goal is to assess the suitability of a glass dosimeter on detection of high-energy electron beams for clinical use, especially for radiation therapy. We examined the dosimetric characteristics of glass dosimeters including dose linearity, reproducibility, angular dependence, dose rate dependence, and energy dependence of 5 different electron energy qualities. The GD was irradiated with high-energy electron beams from the medical linear accelerator andgamma rays from a cobalt-60 teletherapy unit. All irradiations were performed in a water phantom. The result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; R2 of 0.999 between 6 and 20 MeV. The reproducibility of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was +/-1.2%. In terms of the angular dependence to electron beams,GD response differences to the electron beam were within 1.5% for angles ranging from 0degrees to 90degrees and GD's maximum response differencewas 14% lower at 180degrees. In the dose rate dependence, measured dose values were normalized to the value obtained from 500 MU/min. The uncertainties of dose rate were measured within +/-1.5% except for the value from 100 MU/min. In the evaluation of the energy dependence of the GD at nominal electron energies between 6 and 20 MeV, we obtained lower responses between 1.1% and 4.5% based on cobalt-60 beam. Our results show that GDs have a considerable potentiality for measuring doses delivered by high-energy electron beams.