방사선치료 선량 측정에 사용되는 열형광체에 따른 최대 형광 강도 특성 = Characteristics of the Maximum Glow Intensity According to the Thermoluminescent Phosphors used in the Absorbed Dose Measurement of the Radiation Therapy

다국어 초록 (Multilingual Abstract)

mperature of the thermoluminescent dosimeters (TLDs) for the absorbed dose measurement of the radiationtherapy. In this study, we was used the TLDs of the LiF:Mg Ti, LiF:Mg Cu P, CaF2:Dy, CaF2:Mn (ThermoFisher Scientific Inc., USA). The source-to-solid dry phantom (RW3 slab, IBA Dosmetry, Germany) surfacedistance was set at 100 cm, and the exposure dose of 100 MU (monitor unit) was used 6- and 15-MVX-rays, and 6- and 12-MeV electron beams in the reference depth, respectively. After the radiationsexposure, we were to analyze the glow curves by using the TL reader (Hashaw 3500, Thermo FisherScientific Inc., USA) at the fixed heating rate of 15°C/sec from 50°C to 260°C. The glow peaks, the trappinglevel in the captured electrons and holes combined with the emitted light, were discovered the two or threepeak. When the definite increasing the temperature of the TLDs, the maximum glow peak representing theglow 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 dependon the heating temperature after the exposure radiation, TLDs by applying the fixed heating rate, the accuracyof measurement will be able to improve within the absorbed dose measurement of the radiation therapy.

국문 초록 (Abstract)

본 연구는 방사선 치료 영역의 선량 측정을 위하여 상용화된 열형광선량계의 가열 온도에 따른 형광 곡선의 특성을분석하였다. 본 연구에 사용된 열형광선량계는 LiF:Mg Ti, LiF:Mg Cu P, CaF2:Dy, CaF2:Mn(Thermo Fisher Scientific Inc., USA)이었다. 선원과 고체 팬텀 표면(RW3 slab, IBA Dosimetry, Germany)간 거리를 100cm로 하여기준점 깊이에서 6MV, 15MV X선과 6MeV, 12MeV 전자선을 각각 100MU 조사하였다. 방사선 조사 후 열형광 판독기(Hashaw 3500, Thermo Fisher Scientific Inc., USA)를 사용하여 50°C에서 260°C까지 15°C/sec의 가온율로 가열하여 형광 곡선을 분석하였다. 트랩 준위에 포획된 전자가 정공과 결합하면서 빛을 방출하는 형광 피크(glow peak)는 2개 또는 3개의 피크가 나타났으며 방사선 조사 후 TLD의 온도를 일정하게 증가시켰을 때 최대 형광 피크를 나타내는형광 온도의 경우 각각의 에너지에 따라 LiF:Mg·Ti 선량계는 185.5±1.3°C, LiF:Mg·Cu·P 선량계는 135.0±5.1°C,CaF2:Dy 선량계는 144.0±1.6°C, CaF2:Mn 선량계는 294.3±3.8°C 근처에서 최대 형광 피크를 각각 나타났다. 방사선조사 후 포획 전자의 형광 방출 확률은 가열 온도에 의존하게 되므로 방사선 치료 영역의 선량 측정에서 방사선 조사후 열형광선량계에 일정한 가온율을 적용함으로써 고유한 물리적 특성에 따른 측정 정확도를 향상시킬 수 있을 것으로판단되었다.

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