Goorley T, Nikjoo H
Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Radiat Res. 2000 Nov;154(5):556-63. doi: 10.1667/0033-7587(2000)154[0556:eapsft]2.0.co;2.
Some recent neutron capture therapy research has focused on using compounds containing the element gadolinium, which produces internal conversion and Auger cascade electrons. The low-energy, short-range Auger electrons are absorbed locally and increase cell killing dramatically as the gadolinium compounds are introduced into the cell nucleus and bind to the DNA. Detailed electron and photon spectra are needed for biophysical modeling and Monte Carlo calculations of damage to DNA. This paper presents calculated electron and photon spectra for three cases: thermal neutron absorption by (157)Gd, the beta-particle decay of (159)Gd, and the K-shell photoelectric event in gadolinium. The Monte Carlo sampling of atomic and nuclear transitions for each of the three cases was used to calculate a large number of representative decays. The sampled decays were used to determine average emissions and energy deposited in small spheres of tissue. The kinetic energy nuclear recoil from gamma-ray and electron emissions was calculated and found to be more than 10 eV for 26% of all (157)Gd neutron capture reactions.
近期一些中子俘获疗法研究聚焦于使用含钆元素的化合物，该元素会产生内转换和俄歇级联电子。当钆化合物被引入细胞核并与DNA结合时，低能、短程的俄歇电子会被局部吸收，从而显著增强细胞杀伤作用。生物物理建模以及对DNA损伤的蒙特卡罗计算需要详细的电子和光子能谱。本文给出了三种情况的计算电子和光子能谱：（157）Gd的热中子吸收、（159）Gd的β粒子衰变以及钆中的K壳层光电事件。针对这三种情况中的每一种，通过对原子和核跃迁进行蒙特卡罗抽样来计算大量具有代表性的衰变。抽样衰变用于确定平均发射量以及在小组织球体内沉积的能量。计算了γ射线和电子发射产生的动能核反冲，发现对于所有（157）Gd中子俘获反应的26%而言，其大于10电子伏特。
