Affiliations: [a] Department of Medical Physics and Radiology, Faculty of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran
| [b] Department of Computer Engineering and Information Technology, Payame Noor University, Tehran, Iran
| [c] The Advocate Center for Clinical Research, Ayatollah Yasrebi Hospital, Kashan, Iran
Correspondence:
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Corresponding author: Bagher Farhood and Akbar Aliasgharzadeh, Department of Medical Physics and Radiology, Faculty of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran. Tel.: +98 9129234207; Fax: +98 31 55548883;
E-mails: bffarhood@gmail.com (Bagher Farhood); aaliasgharzadeh@yahoo.com (Akbar Aliasgharzadeh).
Abstract: 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 300 cGy/min) and photon energies (6 and 15 MV). 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 0.86 Gy and from 0.27 to 2.20 Gy 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.
Keywords: Polymer gel dosimetry, PASSAG-U, urea, photon energy, dose rate
