Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
Health Phys. 2010 Feb;98(2):309-17. doi: 10.1097/HP.0b013e3181b27502.
Exposure of fingernails and toenails to ionizing radiation creates radicals that are stable over a relatively long period (days to weeks) and characterized by an isotropic EPR signal at g = 2.003 (so-called radiation-induced signal, RIS). This signal in readily obtained fingernail parings has the potential to be used in screening a population for exposure to radiation and determining individual dose to guide medical treatment. However, the mechanical harvesting of fingernail parings also creates radicals, and their EPR signals (so-called mechanically-induced signals, MIS) overlap the g approximately 2.0 region, interfering with efforts to quantify the RIS and, therefore, the radiation dose. Careful analysis of the time evolution and power-dependence of the EPR spectra of freshly cut fingernail parings has now resolved the MIS into three major components, including one that is described for the first time. It dominates the MIS soon after cutting, but decays within the first hour and consists of a unique doublet that can be resolved from the RIS. The MIS obtained within the first few minutes after cutting is consistent among fingernail samples and provides an opportunity to achieve the two important dosimetry objectives. First, perturbation of the initial MIS by the presence of RIS in fingernails that have received a threshold dose of radiation leads to spectral signatures that can be used for rapid screening. Second, decomposition of the EPR spectra from irradiated fingernails into MIS and RIS components can be used to isolate and thus quantify the RIS for determining individual exposure dose.
指甲和趾甲暴露于电离辐射会产生自由基，这些自由基在相对较长的时间（数天到数周）内稳定，并具有各向同性的 EPR 信号，g 值为 2.003（所谓的辐射诱导信号，RIS）。从指甲屑中很容易获得这种信号，有可能用于筛选人群中是否受到辐射，并确定个体剂量以指导治疗。然而，机械采集指甲屑也会产生自由基，其 EPR 信号（所谓的机械诱导信号，MIS）与 g 值约为 2.0 的区域重叠，干扰了对 RIS 进行定量的努力，从而影响了辐射剂量的确定。对新切割的指甲屑的 EPR 光谱的时间演化和功率依赖性的仔细分析，现在已经将 MIS 解析为三个主要成分，其中一个是首次描述的。它在切割后不久就主导了 MIS，但在第一个小时内衰减，并由一个独特的双峰组成，可以与 RIS 区分开来。切割后几分钟内获得的 MIS 在指甲样本之间是一致的，为实现两个重要的剂量测定目标提供了机会。首先，在指甲上存在阈值辐射剂量的情况下，RIS 对初始 MIS 的干扰会导致可以用于快速筛选的光谱特征。其次，从受照射的指甲的 EPR 光谱中分解 MIS 和 RIS 成分，可以用于分离和量化 RIS，以确定个体暴露剂量。
