Calibration and Statistical Performance of Al2O3: C Optically Stimulated Luminescent Dosimeters With and Without Annealing Using a 137Cs Source.

A series of experiments were conducted using commercially available Al2O3:C optically stimulated luminescent dosimeters to provide a technical basis for their precise calibration and statistical performance at irradiated air kerma doses between 0.02 mGy and 5 mGy using Cs. This study examines the dose response linearity, studies the background signal for annealed dosimeters, and compares the statistical performance of dosimeters that were annealed and not annealed prior to their irradiation and readout. The average and standard deviation for the response of groups of dosimeters annealed and nonannealed prior to their irradiation were determined at each delivered dose. The batch of dosimeters that were annealed prior to their irradiation exhibited a coefficient of variation in its mean dose response below 10% when using three or more irradiation trials at each delivered air kerma dose between 0.02 mGy and 5 mGy. The reader calibration factor was calculated using the response of the annealed batch of dosimeters and was determined to be 756 ± 7 photomultiplier tube counts per mGy. Best estimates of the individual sensitivity factors were determined to be between 0.79 and 1.12 for the annealed batch of dosimeters. The minimum number of irradiations required to accurately determine the sensitivity factor of each individual dosimeter is reported with the recommended reader and dosimeter calibration procedures.