Postal intercomparison of absorbed dose for high energy x rays with thermoluminescence dosimeters

Abstract

The accuracy and precision of the IAEA/WHO [International Atomic Energy Agency/ World Health Organization] LiF TLD [thermoluminescent dosimeter] system used in intercomparison by mail of absorbed doses from 60Co .gamma.-radiation and 4-25 MV X-rays was studied. The system employs 160 mg LiF powder in polystyrene capsules, which are placed at 5 or 7 cm depth in water and irradiated to doses close to 200 rad (2.00 Gy [gray]). The dosimeters are mailed to the IAEA Dosimetry Laboratory and read under conditions to minimize variations in instrument sensitivity. The precision of the readout technique, using 3 capsules/irradiation and the readout of 5 aliquots/capsule, is characterized by 0.2% SD of the resulting mean. Since random errors during the irradiation are added, the detectable systematic discrepancy in dose delivery at the 95% confidence level is .+-. 2% for 60Co .gamma. and .+-. 3% for high-energy X-rays.