EFFECTS OF LOW ENERGY ELECTRONS FROM AUGER PROCESSES

几种通过电子俘获(EC)和内部衰变的放射性核素 转换(IC)技术在核医学成像中有着广泛的应用。是这样的 放射性核素还会发射大量低能量和极低能量的俄歇电子， 并可能对生物系统造成广泛的破坏，类似于这种情况 125i。建议对几种常见的放射性物质进行放射毒性研究。 在实验小鼠体内使用放射性核素。精子发生将是 用作观察低能量造成的任何过度损害的模型 来自结合的放射性核素的电子。与效果比较 同一元素的贝塔衰变放射性核素给出了 合并的EC和IC的生物有效性(RBE) 放射性核素。这些信息可能有助于更好地估计 患者性腺生殖细胞的实际辐射剂量 从临床程序中分离出来。观测到的RBE值可能相当大 如果高度局域能量沉积的能量比L要高 电子扮演着重要的角色。已完成的研究表明，相对危险度约为3.5 相对于204T拉姆达，20lT拉姆达。为了理解RBE值， 将进行放射自显影和其他研究，以确定 放射性核素的分布；理论俄歇和科斯特-克罗尼格 将计算电子能谱；适当的剂量学模型将 被开发出来。 低能俄歇电子也提供了新的可能性 探索过了。使用放射性标记的DNA寻找化疗药物，如 顺铂，建议在小鼠肿瘤模型中进行研究 通过降低药物的化疗毒性来提高疗效。

Several radionuclides decaying by electron capture (EC) and internal conversion (IC) are widely used for imaging in Nuclear Medicine. Such radionuclides also emit numerous low and very low energy Auger electrons, and may cause extensive damage in biological systems, similar to the case of 125I. It is proposed to study the radiotoxicity of several commonly used radionuclides in vivo in experimental mice. Spermatogenesis will be used as a model to observe any excessive damage caused by the low energy electrons from the incorporated radionuclides. Comparison with the effects of beta-decaying radionuclides of the same element give the relative biological effectiveness (RBE) of the incorporated EC and IC radionuclides. Such information may be useful to estimate better a realistic radiation dose to the germ cells in the gonads of the patient from the clinical procedures. The observed RBE values may be considerably higher than l if highly localized energy deposition by the low energy electrons plays an important role. Completed studies give RBE of about 3.5 for 20lT lambda relative to 204T lambda. To understand the RBE values, autoradiographic and other studies will be conducted to determine the distribution of the radionuclides; theoretical Auger and Coster-Kronig electron spectra will be calculated; and appropriate dosimetric models will be developed. The low energy Auger electrons also offer new possibilities not yet explored. Using radiolabeled DNA-seeking chemotherapeutic agents such as cis-platimum, it is proposed to investigate in mouse tumor models possible enhancement of therapeutic efficacy with reduced chemotoxicity of the drug.