Open AccessComparison of TLD calibration methods for 192 Ir dosimetry
Author(s) -
Haworth Annette,
Butler Duncan J.,
Wilfert Lisa,
Ebert Martin A.,
Todd Stephen P.,
Hayton Anna J.M.,
Kron Tomas
Publication year - 2013
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1120/jacmp.v14i1.4037
Subject(s) - thermoluminescent dosimeter , dosimeter , imaging phantom , calibration , ionization chamber , dosimetry , nuclear medicine , thermoluminescence , thermoluminescent dosimetry , dwell time , materials science , irradiation , brachytherapy , linear particle accelerator , percentage depth dose curve , optics , physics , medical physics , medicine , ionization , radiation therapy , nuclear physics , radiology , beam (structure) , ion , clinical psychology , quantum mechanics
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 M V. 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. PACS number: 87