A comparison of Cs-137 and x-ray sources as calibration references for thermoluminescent dosimeter chips used in the Saskatchewan postal quality assurance program for diagnostic radiology

This work is focused on calibrating Thermoluminescent Dosimeters (TLDs) using Cs-137 instead of using x-ray. TLD chips which are used in the Saskatchewan Ministry of Labour Postal Quality Assurance (PQA) program were irradiated using X-Ray machine and an AEA Model 773 Cs-137 Instrument Calibrator at known exposure levels. The response was measured to be 0.1275 ± 0.0049 nC per mR for x-ray exposures and 0.0772 ± 0.0028 nC per mR for the Cs-137 exposures. Neither kVp or beam filtration appeared to have any effect on the chip response. These results show that application of an appropriate correction factor k =0.6056 ± 0.0057 will allow chips to be calibrated using Cs-137. (author)