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Thermoluminescence Sheet-type Dosimeter for in Vivo Skin Dosimetry in Passive Scattering Proton Therapy

出版	2017
URL	http://books.google.com.hk/books?id=sdW4zQEACAAJ&hl=&source=gbs_api

註釋Purpose; Considering skin sparing is important in passive scattering proton therapy (PSPT), in which small number of fields may cause high entrance dose. In vivo skin dosimetry (IVSD) is desirable to perceive actual skin dose, however, the methodology of IVSD in PSPT has not yet been established so far. Newly developed thermoluminescence sheet-type dosimeters (TLSD) are particularly suited for applications in IVSD because of their ease of use, and capability of adjusting size. We investigated the utility of TLSD for IVSD in PSPT.Materials and Methods; Lithium triborate (effective atomic number 7.3) is the main component of TLSD (TOYO Medic Ltd., Tokyo, Japan). To evaluate the basic characteristics for proton beams such as dose linearity, uniformity, and energy dependences, unmodulated and modulated proton beams are irradiated to TLSD in parallel or perpendicular to the beam axis in the custom-made water phantom. Furthermore, to measure the actual range shift of the proton beam due to TLSD insertion in the bean line, the proton depth-dose curve measurements were obtained to determine water equivalent thickness (WET) with or without TLSD attached to the entrance wall of the water phantom.Results; The dose response was found to be linear up to 10 Gy. The percent depth-dose and dose profile measured with TLSD well reproduced the results with ionization chamber. The WET without protective sheet was estimated to be approximately 0.2 mm.Conclusion; Although there are some needs for improvement, the impact on range error is almost negligible in IVSD, new TLSD is suitable to be used as IVSD tools in PSPT.