Journal Article Absorbed dose estimation using LET dependence in glow curve of thermoluminescent phosphor Li3B7O12:Cu in therapeutic carbon beams

Chang, Weishan  ,  古場, 裕介  ,  福田, 茂一  ,  Wakabayashi, Genichiro  ,  Saitoh, Hidetoshi  ,  Shinsho, Kiyomitsu

53 ( 12 )  , pp.2028 - 2033 , 2016-05 , Taylor & Francis
A high temperature ratio (HTR) method has been proposed to correct the linear energy transfer (LET) dependence of thermoluminescent (TL) efficiency. However, reports in terms of application of the HTR method are concerned only with thermoluminescence detectors (TLDs) that offer point dose measurement. A slab-type TLD based on TL phosphor Li3B7O12:Cu has been developed and that has the potential to be a 3D dose verification tool. To realize the use of the slab-type TLD for heavy charged particle beam, the HTR method has been considered. To improve the reproducibility of HTR, the slow heating rate method is introduced in this report. The relation between TL-efficiency, HTR and LET for Li3B7O12:Cu was manifested and the TL-efficiency as a function of HTR was derived in an attempt to measure the absorbed dose without LET information. The feasibility of the HTR method in therapeutic carbon beams was evaluated by comparing the dose estimated by Li3B7O12:Cu and by an ionization chamber. The accuracy of dose estimation in carbon beams was improved by using the HTR method, but there is room for further improvement. The use of Li3B7O12:Cu in heavy charged particle beams can be materialized with further improvement of HTR sensitivity.

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