Abstract：
This work builds upon a prior study, examining the dosimetric utility of pencil lead and thin graphitic sheets, focusing upon the measurement of skin doses within the mammographic regime. In recognizing the near soft-tissue equivalence of graphite and the earlier-observed favourable thermoluminescence yield of thin sheets of graphite, this has led to present study of 50 μm thick graphite for parameters typical of external beam fractionated radiotherapy and skin dose evaluations. The graphite layers were annealed and then stacked to form an assembly of 0.5 mm nominal thickness. Using a 6 MV photon beam and delivering doses from 2- to 60 Gy, irradiations were conducted, the assembly first forming a superficial layer to a solid water phantom and subsequently underlying a 1.5 cm bolus, seeking to circumvent the build-up to electronic equilibrium for skin treatments. Investigations were made of several dosimetric properties arising from the thermoluminescence yield of the 50 μm thick graphite slabs, in particular proportionality and sensitivity to dose. The results show excellent sensitivity within the dose range of interest, the thermoluminescence response varying with increasing depth through the stacked graphite layers, obtaining a coefficient of determination of 90%. Acknowledging there to be considerable challenge in accurately matching skin thickness with dose, the graphite sheets have nevertheless shown considerable promise as dosimeters of skin, sensitive in determination of dose from the surface of the graphite through to sub-dermal depth thicknesses.
摘要：
这项工作建立在先前的研究基础上，检查铅笔芯和薄石墨片的剂量学实用性，专注于乳房X光检查方案内的皮肤剂量测量。认识到石墨的接近软组织等效性和较早观察到的石墨薄片的有利热释光产率，这导致了目前研究50μm厚的石墨，用于典型的外束分割放疗和皮肤剂量评估参数。将石墨层退火,然后堆叠以形成0.5mm标称厚度的组件。使用6MV光子束，并提供2至60Gy的剂量，进行了辐照，该组件首先形成固体水模的表面层，然后在1.5厘米的团块下面，寻求规避皮肤治疗中电子平衡的积累。对50μm厚的石墨板的热释光产率产生的几种剂量学特性进行了研究，特别是对剂量的比例和敏感性。结果显示在感兴趣的剂量范围内具有出色的灵敏度，热释光响应随着堆叠的石墨层深度的增加而变化，获得90%的决定系数。承认在准确匹配皮肤厚度和剂量方面存在相当大的挑战，然而，石墨片作为皮肤剂量计显示出相当大的希望，在确定从石墨表面到皮下深度厚度的剂量时很敏感。
