Characteristics of the Maximum Glow Intensity According to the Thermoluminescent Phosphors used in the Absorbed Dose Measurement of the Radiation Therapy

Abstract

The purpose of this study were to analyze the characteristic of the glow curves in order to the glow temperature of the thermoluminescent dosimeters (TLDs) for the absorbed dose measurement of the radiation therapy. In this study, we was used the TLDs of the LiF:Mg Ti, LiF:Mg Cu P, CaF2:Dy, CaF2:Mn (Thermo Fisher Scientific Inc., USA). The source-to-solid dry phantom (RW3 slab, IBA Dosmetry, Germany) surface distance was set at 100 cm, and the exposure dose of 100 MU (monitor unit) was used 6-and 15-MV X-rays, and 6-and 12-MeV electron beams in the reference depth, respectively. After the radiations exposure, we were to analyze the glow curves by using the TL reader (Hashaw 3500, Thermo Fisher Scientific Inc., USA) at the fixed heating rate of 15°C/sec from 50°C to 260°C. The glow peaks, the trapping level in the captured electrons and holes combined with the emitted light, were discovered the two or three peak. When the definite increasing the temperature of the TLDs, the maximum glow peak representing the glow temperature was follow as; LiF:Mg·Ti: 185.5±1.3°C, LiF:Mg·Cu·P: 135.0±5.1°C, CaF2:Dy: 144.0±1.6°C, CaF2:Mn: 294.3±3.8°C, respectively. Because the glow emission probability of the captured electrons depend on the heating temperature after the exposure radiation, TLDs by applying the fixed heating rate, the accuracy of measurement will be able to improve within the absorbed dose measurement of the radiation therapy.