Verification of dose rate and energy dependence of MAGICA polymer gel dosimeter with electron beams

Background: The purpose of this study was to evaluate the dependency of MAGICA polymer gel dosimeter response (R2) on different electron energies as well as on different mean dose rate for a standard clinically used linear accelerator. Materials and Methods: The sensitivity of the dosimeter was represented by the slope of calibration curve in the linear region measured for each modality. A calibration curve (in the linear region) based on 12 dosimeters (11 irradiated and one blank) was obtained for 6 MeV electron beam. Dosimeter energy dependence was studied for electron energies of 4,6,12 and 18 MeV. Dose rate dependence was studied in 10 MeV electron beam with the use of dose rates 80,160,240,320,400 and 480 cGymin(-1). Evaluations of dosimeters were performed on Siemens Symphony, Germany, 1.5T Scanner in the head coil. A multiecho sequence with 32 equidistant echoes was used for the evaluation of irradiated polymer gel dosimeters. The parameters of the sequence were as follows: TR 3000ms, TE 20ms, Slice Thickness 4mm and FOV 256mm. Results: Polymer gel dosimeter response R2 was increased with increasing electron energy. No trend in polymer-gel dosimeter R2 dependence was found on mean dose rate for electron beams. Conclusion: In MAGICA polymer gel, the sensitivity is dependant on electron energy increase, but no dependence was observed on response to dose rate. The presence of antioxidant and oxygen scavengers in the MAGICA polymer gel is believed to cause different results. Iran. J. Radiat. Res., 2008; 6 (1): 31-36