Yang T C, George K, Johnson A S, Tavakoli A, Durante M, Fedorenko B S
NASA Johnson Space Center, Houston, TX 77058, USA.
Aviakosm Ekolog Med. 1997;31(2):8-14.
For assessing health risk, the measurement of physical dose received during a space mission, as well as the LETs, energies and charges of particles is important. It is also important to obtain quantitative information regarding the effectiveness of space radiation in causing damage to critical biological targets, e.g., chromosomes, since at present the estimated uncertainty of biological effects of space radiation is more than a factor of two. Such large uncertainty makes accurate health risk assessment very difficult. For this very reason, a study on cytogenetic effects of space radiation in human lymphocytes was proposed and done for MIR-18 mission. This study used FISH technique to score chromosomal translocations and C-banding method to determine dicentrics. Growth kinetics of cells and SCE were examined to ensure that chromosomal aberrations were scored in first mitosis and were induced not by chemical mutagens. Our results showed that chromosomal aberration frequency of post-flight samples was significantly higher than that of pre-flight ones and that SCE frequency was similar between pre- and post-flight samples. Based on a dose-response curve of preflight samples exposed to gamma rays, the absorbed dose received by crews during the mission was estimated to be about 14.5 cSv. Because the absorbed dose measured by physical dosimeters is 4.16 cGy for the entire mission, the RBE is about 3.5.
对于评估健康风险而言，测量太空任务期间所接受的物理剂量以及粒子的传能线密度（LET）、能量和电荷非常重要。获取有关太空辐射对关键生物靶点（如染色体）造成损伤的有效性的定量信息也很重要，因为目前太空辐射生物效应的估计不确定性超过两倍。如此大的不确定性使得准确的健康风险评估非常困难。正是出于这个原因，针对和平号空间站18号任务提出并开展了一项关于太空辐射对人类淋巴细胞细胞遗传学效应的研究。该研究使用荧光原位杂交（FISH）技术对染色体易位进行计分，并采用C带方法确定双着丝粒。检查细胞的生长动力学和姐妹染色单体交换（SCE），以确保在第一次有丝分裂时对染色体畸变进行计分，并且不是由化学诱变剂诱导产生的。我们的结果表明，飞行后样本的染色体畸变频率显著高于飞行前样本，并且飞行前和飞行后样本之间的SCE频率相似。根据暴露于伽马射线的飞行前样本的剂量反应曲线，估计机组人员在任务期间接受的吸收剂量约为14.5厘希沃特（cSv）。由于整个任务期间物理剂量计测量的吸收剂量为4.16厘戈瑞（cGy），相对生物效应（RBE）约为3.5。
