We aim to improve the accuracy of electron paramagnetic resonance (EPR)-based in vivo tooth dosimetry using the relationship between tooth geometry and radiation-induced signals (RIS). A homebuilt EPR spectrometer at L-band frequency of 1.15 GHz originally designed for non-invasive and in vivo measurements of intact teeth was used to measure the RIS of extracted human teeth. Twenty human central incisors were scanned by microCT and irradiated by 220 kVp x-rays. The RISs of the samples were measured by the EPR spectrometer as well as simulated by using the finite element analysis of the electromagnetic field. A linear relationship between simulated RISs and tooth geometric dimensions, such as enamel area, enamel volume, and labial enamel volume, was confirmed. The dose sensitivity was quantified as a slope of the calibration curve (i.e., RIS vs. dose) for each tooth sample. The linear regression of these dose sensitivities was established for each of three tooth geometric dimensions. Based on these findings, a method for the geometry correction was developed by use of expected dose sensitivity of a certain tooth for one of the tooth geometric dimensions. Using upper incisors, the mean absolute deviation (MAD) without correction was 1.48 Gy from an estimated dose of 10 Gy; however, the MAD corrected by enamel area, volume, and labial volume was reduced to 1.04 Gy, 0.77 Gy, and 0.83 Gy, respectively. In general, the method corrected by enamel volume showed the best accuracy in this study. This homebuilt EPR spectrometer for the purpose of non-invasive and in vivo tooth dosimetry was successfully tested for achieving measurements in situ. We demonstrated that the developed correction method could reduce dosimetric uncertainties resulting from the variations in tooth geometric dimensions.

中文翻译：

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使用 1.15 GHZ 电子顺磁共振波谱仪测量辐射感应信号对牙釉质几何形状的依赖性：提高剂量测定精度。


我们的目标是利用牙齿几何形状和辐射感应信号（RIS）之间的关系来提高基于电子顺磁共振（EPR）的体内牙齿剂量测定的准确性。自制 EPR 光谱仪，L 波段频率为 1.15 GHz，最初设计用于完整牙齿的非侵入性活体测量，用于测量拔除的人类牙齿的 RIS。通过 microCT 扫描 20 颗人类中切牙并接受 220 kVp X 射线照射。通过 EPR 光谱仪测量了样品的 RIS，并通过电磁场有限元分析进行了模拟。模拟 RIS 与牙齿几何尺寸（如牙釉质面积、牙釉质体积和唇釉质体积）之间的线性关系已得到证实。剂量敏感性被量化为每个牙齿样本的校准曲线的斜率（即，RIS 与剂量）。针对三个牙齿几何尺寸中的每一个建立了这些剂量敏感性的线性回归。基于这些发现，通过使用特定牙齿对于其中一个牙齿几何尺寸的预期剂量敏感性，开发了一种几何校正方法。使用上切牙，未校正的平均绝对偏差 (MAD) 与估计剂量 10 Gy 相比为 1.48 Gy；然而，通过牙釉质面积、体积和唇体积校正的 MAD 分别降低至 1.04 Gy、0.77 Gy 和 0.83 Gy。总的来说，本研究中通过牙釉质体积校正的方法显示出最好的准确性。这种用于非侵入性体内牙齿剂量测定的自制 EPR 光谱仪已成功进行原位测量测试。 我们证明了所开发的校正方法可以减少由于牙齿几何尺寸变化而导致的剂量测定不确定性。