Evaluation of time-stability response of gelatin-Trimesic acid dosimeter

Introduction: One of the problems in chemical dosimeters such as Trimesic acid is the liquid environment which makes it difficult to use. Chemical dosimeter merged into a bed of gel can help to partly overcome this problem.According to the importance of stability of dosimeter response after irradiation, in this study, the parameters of gelatin- Trimesic acid dosimeter in the range of doses of a one fraction of radiotherapy was assessed in days one, two, three and four after irradiation. Materials and Methods: After the gel construction at a concentration of 1 mM and a pH of 2.2, it was poured into Perspex vials which opening was tight with parafilm and wrapped in an aluminum foil to eliminate light and was divided into 5 groups to be irradiated with 6 MV photons of linac 24h after the gel synthesis. To do so, vials were place at the isocenter of the linac in a SSD of 100cm and field size of 10 � 10 cm2. The delivered doses were from 0-200 cGy and vials were kept at the temperature of 4 �C after the irradiation. The procedure of reading the vials were performed using a spectroflourimeter (Jasco 6200) from one to four days after irradiation in excitation wavelengths of 370, 380, 390, 410, 420 and 450 nm. Results: After obtaining the emission spectrum from the spectroflourimeter, the emission spectrum was analyzed and it was found that there is a peak in the wavelengths of 377, 387, 396, 416, 427 and 457 nm seen in one day after irradiation and the most stable response belongs to the first day after irradiation. Conclusion: The results of this study showed that the combined gelatin- Trimesic acid dosimeter in the first day after irradiation has the highest and most stable response and according to its characteristics, has the potential to be assessed as a clinical dosimeter. � 2016, Semnan University of Medical Sciences. All rights reserved