Thermoluminescent relative efficiency of TLD-100 glow peaks after exposure to X-rays of 20 kV–300 kV, 137Cs and 60Co gamma

Abstract

Thermoluminescent dosimeter LiF:Mg, Ti (TLD-100) has been considered as the “gold standard” to measure absorbed dose from low-energy photon fields in medical applications. However, to calibrate the dosimeters, high energy beams (6 MV X-ray or 60Co gamma) are usually used since low photon energy beams are not always available. Thus, knowledge of the relative efficiency, RE, is necessary in order to convert the absorbed dose calibration from high energy beams to low-energy photon fields like those used in brachytherapy and diagnostic. In this work, RE as a function of the photon energy, besides, the influence of the phantom material used to collocate the dosimeters during irradiation has been studied. Thermoluminescent glow curves were deconvolved into 9 individual glow peaks by using an algorithm developed in Matlab based on the Podgorsak approximation using the first-order kinetics model. The influence of the phantom material on the dosimeter response is observed in every glow peak, where RE values are lower in air compared to other materials such as polymethyl methacrylate. For all the glow peaks, RE as a function of the mean photon energy shows a region with a minimum and a maximum.