Abstract 9B and H grade carbon-based pencil (carbon concentrations approaching 81 and 62 wt respectively %) have been investigated for radiotherapy dosimetry applications, offering low dependence on photon energy and near soft tissue effective atomic number. Comparison has been made with highly oriented pyrolytic graphite (HOPG), a pure and ordered synthetic form of graphite. The samples were exposed to 60Co gamma ray doses from 0 to 20 Gy (encompassing the range of doses utilized in fractionated radiotherapy), structural interaction alterations resulting from the radiation doses being observed via Raman and Photoluminescence (PL) spectroscopy and X-ray diffraction (XRD). Among the most prominent features to be observed in Raman spectra are the so-called G and D peaks, appearing at 1578 cm−1 and 1348 cm−1 respectively. The intensity ratio ID/IG was used for further characterization of the dose-dependent defects produced in the graphitic materials. From PL measurement, sample average energy band gap values are observed to be within the region 1.114–1.116 eV, being considered direct bandgap-like semiconductors. The characteristic XRD crystal plane Miller index (002) peak was observed in order to calculate the atomic spacing, lattice constant and the degree of structural order of the irradiated samples.

中文翻译：

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伽马辐照富石墨铅笔结构变化的剂量学效用

摘要 9B 和 H 级碳基铅笔（碳浓度分别接近 81 和 62 重量％）已被研究用于放射治疗剂量测定应用，提供对光子能量和近软组织有效原子序数的低依赖性。已经与高度取向的热解石墨 (HOPG) 进行了比较，这是一种纯有序的石墨合成形式。样品暴露于 0 到 20 Gy 的 60Co 伽马射线剂量（包括分次放疗中使用的剂量范围），通过拉曼和光致发光 (PL) 光谱和 X 射线衍射观察到辐射剂量导致的结构相互作用改变（ XRD）。在拉曼光谱中观察到的最突出的特征是所谓的 G 和 D 峰，分别出现在 1578 cm-1 和 1348 cm-1。强度比 ID/IG 用于进一步表征石墨材料中产生的剂量依赖性缺陷。从 PL 测量中，观察到样品平均能带隙值在 1.114-1.116 eV 区域内，被认为是直接带隙半导体。观察特征XRD晶面米勒指数(002)峰，以计算辐照样品的原子间距、晶格常数和结构有序度。