Irradiation temperature effect on glutamine (spectrophotometric readout) dosimeter

Abstract

For the dose estimation using glutamine dosimeter, 20 mg l-glutamine powder is dissolved in 10 ml of a solution which contains 2×10 −3 mol dm −3 ferrous ammonium sulphate and 10 −4 mol dm −3 xylenol orange in aerated aqueous 0.033 mol dm −3 sulphuric acid (FX). The plot of absorbance at 549 nm against dose is non-linear, however, the plot of 1/absorbance vs. 1/dose is linear. The slope of this linear plot changes above an absorbance of 0.3 corresponding to a dose of about 15 kGy. The response of the dosimeter is independent of irradiation temperature in the temperature range of 23–30°C within the uncertainty of dose measurement. Below 23°C, the absorbance decreases by 1.23% per °C decrease in temperature while between 30 and 40°C, the absorbance increases by 0.75% per °C increase in temperature. Above 40°C, the absorbance increases by 0.2% per °C only. The absorbance is corrected for the irradiation temperature and the dose is read from a calibration graph at 25°C. Either a linear or polynomial relation can be used for the dose calculation.