Radiochromic Gel Dosimeter (FXG) Chemical Yield Determination for Dose Measurements Standardization

摘要

Different gel dosimetry techniques have been proposed as methods for three dimensional dose distribution measurements. Gel dosimeters were proposed for radiotherapy dosimetry at which the calibration of any dose-measuring technique is the main requirement for its proper practical application. The standardisation of the technique requires the establishment of a method for the calibration of each type of these gel materials. The aim of this study is to determine the chemical yield for the radiochromic "Ferrous-sulphate and Xelenol-orange Gelatin" (FXG) gel. Using standard absorbed dose to water protocol, the radiation field is calibrated first; then a standard Fricke solution dosimeter is calibrated. The obtained chemical yield for Fricke is G(Fe~(3+)) velence 1.68X10~(-6) [mol. J~(-1)]. Finally, FXG dosimeter was calibrated against the standard Fricke solution before calculating the system chemical yield and comparing its value with Fricke system. The results show that epsilon.G (FXG) velence 6093.1 [m~(2). J~(-1)] velence 19.5Xepsilon.G (Fricke). Compared with the Fricke system, the FXG dosimeter has much higher sensitivity. Additionally, the overall accuracy and reproducibility of the gel detector was also comparable to those reported for Fricke solution. However, the FXG dosimeter properties could be improved further through the establishment of a defined manufacturing procedures and calibration method; as well as precise selection of sensitive materials and radiation effects evaluation techniques.