Grossi G, Durante M, Gialanella G, Pugliese M, Scampoli P, Furusawa Y, Kanai T, Matsufuji N
Department of Physical Sciences, University of Naples Federico II and INFN, Napoli, Italy.
Adv Space Res. 2004;34(6):1358-61. doi: 10.1016/j.asr.2003.09.060.
Biophysical models are commonly used to evaluate the effectiveness of shielding in reducing the biological damage caused by cosmic radiation in space flights. To improve and validate these codes biophysical experiments are needed. We have measured the induction of chromosomal aberrations in human peripheral blood lymphocytes exposed in vitro to 500 MeV/n iron ion beams (dose range 0.1-1 Gy) after traversing shields of different material (lucite, aluminium, or lead) and thickness (0-11.3 g/cm2). For comparison, cells were exposed to 200 MeV/n iron ions and to X-rays. Chromosomes were prematurely condensed by a phosphatase inhibitor (calyculin A) to avoid cell-cycle selection produced by the exposure to high-LET heavy-ion beams. Aberrations were scored in chromosomes 1, 2, and 4 following fluorescence in situ hybridization. The fraction of aberrant lymphocytes has been evaluated as a function of the dose at the sample position, and of the fluence of primary 56Fe ions hitting the shield. The influence of shield thickness on the action cross-section for the induction of exchange-type aberrations has been analyzed, and the dose average-LET measured as a function of the shield thickness. These preliminary results prove that the effectiveness of heavy ions is modified by shielding, and the biological damage is dependent upon shield thickness and material.
生物物理模型通常用于评估屏蔽在减少太空飞行中宇宙辐射所造成的生物损伤方面的有效性。为了改进和验证这些代码，需要进行生物物理实验。我们测量了人类外周血淋巴细胞在体外暴露于500 MeV/n铁离子束（剂量范围0.1 - 1 Gy）后，穿过不同材料（有机玻璃、铝或铅）和厚度（0 - 11.3 g/cm²）屏蔽层时染色体畸变的诱导情况。作为对比，细胞还暴露于200 MeV/n铁离子和X射线下。通过磷酸酶抑制剂（花萼海绵诱癌素A）使染色体提前浓缩，以避免因暴露于高传能线密度重离子束而产生的细胞周期选择。在荧光原位杂交后，对1号、2号和4号染色体上的畸变进行评分。已将异常淋巴细胞的比例评估为样品位置处剂量以及撞击屏蔽层的初级56Fe离子注量的函数。分析了屏蔽层厚度对诱导交换型畸变的作用截面的影响，并测量了剂量平均传能线密度作为屏蔽层厚度的函数。这些初步结果证明，重离子的有效性会因屏蔽而改变，并且生物损伤取决于屏蔽层的厚度和材料。
