Effects of absorbed dose rate, irradiation temperature and post-irradiation temperature on the gamma ray response of red Perspex dosimeters

The influences of irradiation temperature and gamma radiation dose rate on the response of red 4034 Perspex dosimeters have been reported in the literature to be of relatively minor consequence, particularly for irradiations at up to a temperature of 40 deg. C and at absorbed dose rates of the order of 7 kGy·h-1 (∼2 Gy·s-1). The present study shows this to be true; however, if there are marked differences in the temperature (22 deg. C to 50 deg. C) during extended storage periods (up to 16 hours) after irradiation, there is a tendency to overestimate an unknown dose administered at the elevated temperature, as a result of using a calibration made at an ambient lower temperature (e.g. 22 deg. C). The present study of dose rate effects also shows that there is a pronounced tendency to overestimate an unknown gamma ray dose administered at a relatively low dose rate (3 and 7 kGy·h-1) as a result of using a calibration made at a considerably higher dose rate (e.g. 31 kGy·h-1), even when the temperature of irradiation and storage is controlled at 22 deg. C. (author). 14 refs, 13 figs