Use of track-end alpha particles from 241Am to study radiosensitive sites in CHO cells.
Use of track-end alpha particles from 241Am to study radiosensitive sites in CHO cells.
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使用 241Am 的轨道末端 α 粒子研究 CHO 细胞中的放射敏感位点。
作者：
R. Datta;A. Cole;S. Robinson
放置在膜过滤器上的CHO细胞的单层被来自$sup 241$Am源的阿尔法粒子照射。通过将细胞样品放置在与源不同的距离来控制粒子对细胞的渗透。使用平行板电离室和闪烁晶体光谱仪在可比较的位置进行剂量测量和光谱测量。按照传统的克隆技术衡量，细胞存活在形式上是单击式的。观察到平均致死剂量为29rad的阿尔法粒子束，其穿透率仅为3×10~3×10~(-6)×10~(-6)×10~(-6)埃。仅穿透细胞5~7×10~3×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)mm~(-1)的束流，失活截面最大值为90×10~3×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)×10~(-6)。因此，单个阿尔法粒子在细胞核内穿透几微米就能有效地杀死细胞，而完全穿透的光束实际上效率较低；后一种光束需要多次粒子穿越，大约是细胞剂量的三倍才能达到同样的效果。这些结果支持辐射敏感部位位于核内较薄的周边区域的说法。(身份验证)
Monolayers of CHO cells placed on membrane filters were irradiated with alpha particles from a $sup 241$Am source. Particle penetration into the cells was controlled by placing the cell sample at various distances from the source. Dosimetric and spectrometric measurements were performed at comparable positions using a parallel plate ionization chamber and a scintillation crystal spectrometer. Cell survival, as measured by conventional cloning techniques, was single hit in form. A pronounced minimum in mean lethal dose of 29 rad was observed for alpha particle beams that penetrated only about 3 $mu$m into the cell. A pronounced maximum in inactivation cross section of 90 $mu$m$sup 2$, equal to about half the projected area of the nucleus, occurred for beams that penetrated only 5 to 7 $mu$m into the cell. Thus, a single alpha particle penetration several micrometers within the cell nucleus was effective in killing the cell, while fully penetrating beams were actually less efficient; the latter beams required multiple particle traversals and about three times the cell dose to achieve the same effect. These results support the proposal that radiosensitive sites are located in a thin peripheral region of the nucleus. (auth)