IN VIVO EPR DOSIMETRY AT LOW FREQUENCY: ASSESS RADIATION EXPOSURE USING TEETH

这项研究的长期目的是确定 用活体电子顺磁共振评估辐射剂量的可行性 意外暴露在辐射中。目前的研究主要集中在 低频(L波段)电子顺磁共振波谱用于核磁共振研究的可行性 长寿命辐射诱发的电子顺磁共振信号的测量 活体大鼠的牙齿，并将其与 孤立的人类牙齿。牙齿中辐射诱发的EPR信号具有 基于其形状和功率饱和度的独特特征。 牙齿的使用还有一个好处，那就是提供了一个非常 用灵敏的谐振器可以很容易地实现良好的几何形状 完全非侵入性的活体测量。这些结果表明 有可能开发出技术和仪器 将允许这些测量最终以非侵入性方式在 人类。我们现在已经完成了对 来自活体和分离大鼠牙齿的辐射诱导信号 人类的牙齿。最初，来自大鼠牙齿的信号强度 接收到的X射线辐射非常弱，因为它的体积很小，而且 重量(约100毫克)，所以虽然它可以用X-波段EPR检测到，但非常 用L频段观察，需大剂量观察。因此，我们做了一个 专为老鼠牙齿设计的新环形谐振器，增加了 对有用水平的敏感性。我们还使用了新的谐振器来 从分离的人类牙齿中获取数据，目前的限制为 检测剂量约为1Gy.进一步的技术开发应该延长 甚至更低的剂量。我们得出结论，人类体内的EPR 剂量学将是可行的。

The long-term purpose of this research is to determine the feasibility of using in vivo EPR to assess radiation does in accidental exposures to radiation. The current research focuses on the feasibility of using low frequency (L-band) EPR spectroscopy for the measurement of long-lived radiation-induced EPR signals in the teeth of living rats and to compare this with similar measurements in isolated human teeth. The radiation-induced EPR signal in teeth has distinctive characteristics based on its shape and power saturation. The use of teeth also has the advantage of providing a site where very good geometry with a sensitive resonator can readily be achieved for entirely non-invasive measurements in vivo. These results suggest that it may be possible to develop techniques and instruments that will allow these measurements eventually to be made non-invasively in humans. We now have completed the initial measurements of radiation-induced signals from the teeth of living rats and isolated human teeth. Initially the signal intensity from rat teeth which received X-ray radiation was quite weak due to its very small size and weight (about 100mg), so while it was detectable with X-band EPR, very high doses were needed to observe it with L-band. We therefore made a new loop resonator specially designed for rat teeth and this increased the sensitivity to a useful level. We also used the new resonator to obtain data from isolated human teeth with a present limit of detection of about 1Gy. Further technical developments should extend this to even lower doses. We conclude that human in vivo EPR dosimetry will be feasible.