RESUMO
OBJECTIVE: Several physical factors such as dose rate and photon energy may change response and sensitivity of polymer gel dosimeters. This study aims to evaluate the R2-dose response and sensitivity dependence of PASSAG-U gel dosimeters with 3% and 5% urea on dose rate and photon energy. MATERIALS AND METHODS: The PASSAG-U gel dosimeters were prepared under normal atmospheric conditions. The obtained gel dosimeters were irradiated to different dose rates (100, 200, and 300âcGy/min) and photon energies (6 and 15âMV). Finally, responses (R2) of the PASSAG-U gel dosimeters with 3% and 5% urea were analyzed by MRI technique at 1, 10, 14 days after the irradiation process. RESULTS: The findings showed that the R2-dose responses of PASSAG-U gel dosimeters with 3% and 5% urea do not vary under the differently evaluated dose rates and photon energies. The R2-dose sensitivity of PASSAG-U polymer gel dosimeter with 3% urea does not change under the differently evaluated dose rates and photon energies, but it changes for PASSAG-U polymer gel dosimeter with 5% urea. The dose resolution values ranged from 0.20 to 0.86âGy and from 0.27 to 2.20âGy for the PASSAG-U gel dosimeter with 3% and 5% urea for the different dose rates and photon energies, respectively. Furthermore, it was revealed that the R2-dose response and sensitivity dependence of PASSAG-U gel dosimeters with 3% and 5% urea on dose rate and photon energy can vary over post irradiation time. CONCLUSIONS: The study results demonstrated that dosimetric characteristics (dependence of dose rate and photon energy, and dose resolution) of PASSAG-U gel dosimeter with 3% were better than those of PASSAG-U gel dosimeter with 5% urea.
