title: Comparison of TLD calibration methods for 192Ir dosimetry.
abstract: For the purpose of dose measurement using a high-dose rate (192)Ir source, four methods of thermoluminescent dosimeter (TLD) calibration were investigated. Three of the four calibration methods used the (192)Ir source. Dwell times were calculated to deliver 1 Gy to the TLDs irradiated either in air or water. Dwell time calculations were confirmed by direct measurement using an ionization chamber. The fourth method of calibration used 6 MV photons from a medical linear accelerator, and an energy correction factor was applied to account for the difference in sensitivity of the TLDs in (192)Ir and 6 MV. The results of the four TLD calibration methods are presented in terms of the results of a brachytherapy audit where seven Australian centers irradiated three sets of TLDs in a water phantom. The results were in agreement within estimated uncertainties when the TLDs were calibrated with the (192)Ir source. Calibrating TLDs in a phantom similar to that used for the audit proved to be the most practical method and provided the greatest confidence in measured dose. When calibrated using 6 MV photons, the TLD results were consistently higher than the (192)Ir-calibrated TLDs, suggesting this method does not fully correct for the response of the TLDs when irradiated in the audit phantom.
authors: Dept. Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia. annette.haworth@petermac.org
authors: Annette
authors: A
authors: Haworth
authors: Duncan J
authors: DJ
authors: Butler
authors: Lisa
authors: L
authors: Wilfert
authors: Martin A
authors: MA
authors: Ebert
authors: Stephen P
authors: SP
authors: Todd
authors: Anna J M
authors: AJ
authors: Hayton
authors: Tomas
authors: T
authors: Kron
mesh_terms: D000465:Algorithms; D001315:Australia; D002138:Calibration; D019544:Equipment Failure Analysis / Q000379:methods / Q000592:standards; D007496:Iridium Radioisotopes / Q000032:analysis*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000592:standards*
chemical_list: D007496:Iridium Radioisotopes