EFFECT OF TARGETED LOW DOSE RADIATION TREATMENT ON TUMOR OXYGENATION

这项研究的长期目的是确定 使用体内EPR评估辐射剂量的可行性 意外暴露于辐射。 目前的研究重点是 使用低频（L波段）EPR光谱的可行性， 长寿命辐射诱发EPR信号的测量 活老鼠的牙齿，并将其与类似的测量结果进行比较， 分离的人类牙齿 牙齿中的辐射诱导EPR信号具有 基于其形状和功率饱和度的独特特性。 牙齿的使用还有一个好处， 可以容易地实现具有灵敏谐振器的良好几何形状 完全无创的体内测量。 这些结果表明 有可能开发出技术和工具， 将使这些测量最终能够以非侵入性的方式进行， 人类 我们现在已经完成了对 辐射诱导的信号从活老鼠的牙齿和分离 人类的牙齿 最初，来自老鼠牙齿的信号强度， 接收到的X射线辐射由于其非常小的尺寸而非常弱， 重量（约100毫克），因此，虽然它是与X波段EPR检测，非常 用L波段观察需要更高剂量。 因此，我们制定了 专门为老鼠牙齿设计的新型环形谐振器， 敏感度到一个有用的水平。 我们还使用新的谐振器， 从离体人类牙齿获得数据， 检测剂量约为1Gy。 进一步的技术发展应扩大 甚至更低的剂量。 我们的结论是，人在体内EPR 剂量测定是可行的。

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.