The Secondary Photoelectron Effect: Gamma Ray Ionisation Enhancement in Tissues from High Atomic Number Elements

C. C. Busby
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引用次数: 3

Abstract

The absorption of gamma rays is roughly proportional to the fifth power of the atomic number of an element. This immediately raises the issue of tissue ionisation enhancement effects from photoelectron production by elements of high atomic number incorporated into living tissue. The issue was raised in the 1950s in relation to calcium in the bone but has received little attention since then. New results, derived from mathematical modelling carried out at the University of Ulster, of photoemission from nanoparticles of gold and uranium are presented. These show that significant ionisation enhancement effects can occur when incorporated particles of high atomic number are exposed to natural background gamma radiation, effects which increase sharply at the lower energy end of the spectrum, around 150 keV. The effects must also occur for molecular species. The general problem is discussed, with reference to the literature, and approximate enhancement factors are derived for the effect. The implications for the evolutionary selection of elements by life are explored.
二次光电子效应:高原子序数元素组织中的伽马射线电离增强
对伽马射线的吸收大致与元素原子序数的五次方成正比。这立即提出了由高原子序数元素并入活组织的光电子产生的组织电离增强效应的问题。这个问题是在20世纪50年代提出的,与骨骼中的钙有关,但从那时起就很少受到关注。在阿尔斯特大学进行的数学建模中,提出了金和铀纳米粒子光发射的新结果。这些表明,当高原子序数的合并粒子暴露于自然背景伽马辐射时,会发生显著的电离增强效应,这种效应在光谱的较低能量端(约150 keV)急剧增加。这种效应也必须发生在分子物种上。参考文献,讨论了一般问题,并导出了近似的增强因子。探讨了生命对元素的进化选择的影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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