Roeske J C, Stinchcomb T G
University of Chicago, Department of Radiation and Cellular Oncology, Illinois 60637, USA.
Radiat Res. 1996 Mar;145(3):268-73.
Cell survival studies are a means of quantifying the biological effects of radiation. However, for alpha-particle sources, the dose-response relationship is complicated by the dominance of microdosimetric effects. In this work, we relate observed cell survival to the microdosimetric energy deposition spectra. The chord length distributions through spherical cell nuclei for sources distributed inside of, on the surface of and outside of the critical target are used as approximate analytical representations of the single-event specific energy spectra. Mathematical relationships are derived which relate cell survival to the Laplace transform of the single-event specific energy spectrum. The result is an analytical relationship between D0 (the observed slope of the cell survival curve) and Z0 (the specific energy required to reduce the survival probability of a single cell to 1/e). These studies indicate that for small energy deposition events, Z0 is approximately equal to D0. However, as the maximum energy deposited by a single event is increased, there are marked deviations between Z0 and D0. These differences between Z0 and D0 are also related to the shape of the single-event spectrum. This technique provides a powerful tool for relating observed cell survival to microdosimetric quantities for therapeutic alpha-particle emitters.
细胞存活研究是量化辐射生物学效应的一种手段。然而，对于α粒子源，剂量响应关系因微剂量学效应的主导作用而变得复杂。在这项工作中，我们将观察到的细胞存活与微剂量学能量沉积谱联系起来。对于分布在关键靶点内部、表面和外部的源，通过球形细胞核的弦长分布被用作单事件比能谱的近似解析表示。推导出了将细胞存活与单事件比能谱的拉普拉斯变换联系起来的数学关系。结果是得到了D0（观察到的细胞存活曲线的斜率）与Z0（将单个细胞的存活概率降低到1/e所需的比能）之间的解析关系。这些研究表明，对于小能量沉积事件，Z0大约等于D0。然而，随着单事件沉积的最大能量增加，Z0和D0之间存在明显偏差。Z0和D0之间的这些差异也与单事件谱的形状有关。该技术为将观察到的细胞存活与治疗性α粒子发射体的微剂量学量联系起来提供了一个强大的工具。
