The impact of various amounts of fabricating components on the response of PASSAG polymer gel dosimeter: An optimization study

Polymer gel dosimeters are used to measure three-dimensional dose distribution with high spatial resolution. Recently, a novel polymer gel dosimeter, known as PASSAG, has been introduced in which has several advantages over other polymer gel dosimeters; however, its response-dose sensitivity is relatively low. It has been shown that the sensitivity of polymer gel dosimeters can be changed by various amounts of components used in their fabrication. This study aims to assess the dosimetric characteristics of PASSAG gel dosimeter for different amounts of components in its formulation. For this purpose, different formulations of PASSAG gel dosimeter were first fabricated, and then they were irradiated using 6 MV X-rays in a 0–10 Gy dose range. After the irradiation process, the responses (R2) of gel dosimeters were read out by a 1.5 T MRI scanner during one-month post irradiation time. According to the results, the maximum R2-dose sensitivity belonged to PASSAG gel dosimeter with 5% gelatin, 4% AMPS sodium salt (as monomer), and 4% Bis (as crosslinker) that showed a 31% increased sensitivity compared to conventional PASSAG gel dosimeter (5% gelatin, 3% monomer, and 3% crosslinker). Moreover, an excellent linear R2-dose response was observed for optimized PASSAG gel dosimeter. The dose resolution values of optimized PASSAG gel dosimeter also varied between 0.14 and 0.42 Gy in a 0–10 Gy dose range. Other findings revealed that the R2 values of the optimized gel dosimeter had a relative stability during 15–18 °C and 20–24 °C scanning temperatures. Furthermore, a temporal stability in the R2 values of the optimized gel dosimeter was observed during 15–30 days post irradiation time. The R2-dose sensitivity of optimized gel dosimeter also varied during 30 days post-irradiation time (from 31.00% to 47.97%).