Thermoluminescence (TL) and microstructural analysis were conducted on natural flake graphite (NFG) to assess its suitability for radiotherapeutic x-ray dose measurements. The investigations encompassed the examination of TL glow curves, linearity, sensitivity, signal decay, and repeatability. NFG samples were exposed to Co gamma radiation doses ranging from 2 Gy to 20 Gy. The microstructure of the irradiated NFG was probed using a 532 nm laser Raman spectrometer. Promisingly, the NFG exhibited remarkable characteristics, including a moderately higher response to dose (R of about 96%), increased sensitivity at lower doses, and good repeatability (∼4%). Nevertheless, its fading rate reached about 80% after 14 days of irradiation. Additionally, the NFG intensity ratios of defect (D) to graphite (G), denoted as I/I, closely mirrored the oscillatory pattern observed in 50 μm thick graphite sheets and were approximately 1.6 times lower than those of similar graphite sheets with comparable carbon content (about 98% carbon). These findings suggest that NFG holds potential for the development of an affordable, non-hygroscopic, and tissue-equivalent TL dosimeter, with possible applications in the medical field.

中文翻译：

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γ辐照天然鳞片石墨的热释光剂量测定和微观结构特征

对天然鳞片石墨 (NFG) 进行热释光 (TL) 和微观结构分析，以评估其对放射治疗 X 射线剂量测量的适用性。研究包括检查 TL 发光曲线、线性度、灵敏度、信号衰减和可重复性。 NFG 样品暴露于 2 Gy 至 20 Gy 的 Co 伽马辐射剂量下。使用 532 nm 激光拉曼光谱仪探测辐照 NFG 的微观结构。令人鼓舞的是，NFG 表现出显着的特征，包括对剂量的适度较高的响应（R 约为 96%）、较低剂量下的灵敏度增加以及良好的重复性（∼4%）。然而，照射14天后其褪色率达到80%左右。此外，缺陷 (D) 与石墨 (G) 的 NFG 强度比（表示为 I/I）密切反映了在 50 μm 厚的石墨片中观察到的振荡模式，并且比具有可比碳的类似石墨片低约 1.6 倍含量（约98%碳）。这些研究结果表明，NFG 具有开发经济实惠、不吸湿且组织等效 TL 剂量计的潜力，并可能在医学领域得到应用。