Dose Response Characteristics in Polymer Gel for the Composition Ratio

Abstract

Although a gel dosimeter is not widely used, it has many potential merits for 3D dosimetry in the development of radiotherapy techniques. Because conventional gel dosimeters tend to sensitively polymerize with oxygen. A new polymer gel that solves these problems was introduced recently. The gel dosimeter contains anti-oxidants that eliminate oxygen chemically instead of using complicated facilities. The type and the concentration of the monomer affect the polymerization of the polymer gel dosimeter. Therefore, the polymerization of the normoxic polymer gel dosimeter is affected by anti-oxidant, the monomer, the constituent ratio, and the condition of the monomer, so many researchers have concentrated on the anti-oxidant, the type of monomer, and the constituent ratio. In this study, a normoxic polymer gel dosimeter was composed using anti-oxidants in a laboratory, and the dose response and sensitivity were measured. The results of this study are as follow the threshold R2 values were reduced, and the radio sensitivity was reduced with the increasing MAA ratio. Otherwise, the increase in the gelatin represented an increase and decrease in the threshold value of R2 values and the radio sensitivity, respectively. Therefore, in this study, 6 − 8 % MAA ratios and an 8 % gelatin ratio, considering the aging effect of the gel, were the optimal values.