Yang T C, George K, Johnson A S, Durante M, Fedorenko B S
NASA Johnson Space Center, Houston, Texas 77058, USA.
Radiat Res. 1997 Nov;148(5 Suppl):S17-23.
Astronauts are classified as radiation workers due to the presence of ionizing radiation in space. For the assessment of health risks, physical dosimetry has been indispensable. However, the change of the location of dosimeters on the crew members, the variation in dose rate with location inside the spacecraft and the unknown biological effects of microgravity can introduce significant uncertainties in estimating exposure. To circumvent such uncertainty, a study on the cytogenetic effects of space radiation in human lymphocytes was proposed and conducted for Mir-18, a 115-day mission. This study used fluorescence in situ hybridization (FISH) with whole-chromosome painting probes to score chromosomal exchanges and the Giemsa staining method to determine the frequency of dicentrics. The growth kinetics of cells and sister chromatid exchanges (SCEs) were examined to ensure that chromosomal aberrations were scored in the first mitosis and were induced primarily by space radiation. Our results showed that the frequency of chromosomal aberrations increased significantly in postflight samples compared to samples drawn prior to flight, and that the frequency of SCEs was similar for both pre- and postflight samples. Based on a dose-response curve for preflight samples exposed to gamma rays, the absorbed dose received by crew members during the mission was estimated to be about 14.75 cSv. Because the absorbed dose measured by physical dosimeters is 5.2 cGy for the entire mission, the RBE is about 2.8.
由于太空中存在电离辐射，宇航员被归类为辐射工作人员。对于健康风险评估而言，物理剂量测定一直是必不可少的。然而，剂量计在机组人员身上位置的变化、航天器内剂量率随位置的变化以及微重力未知的生物学效应，可能会在估计辐射暴露时引入显著的不确定性。为规避此类不确定性，针对为期115天的和平号空间站18号任务，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。本研究使用全染色体涂染探针的荧光原位杂交（FISH）技术来记录染色体交换情况，并采用吉姆萨染色法来确定双着丝粒的频率。对细胞的生长动力学和姐妹染色单体交换（SCE）进行了检测，以确保在第一次有丝分裂时记录染色体畸变情况，并且这些畸变主要是由太空辐射诱导产生的。我们的结果表明，与飞行前采集的样本相比，飞行后样本中的染色体畸变频率显著增加，并且飞行前和飞行后样本的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14.75厘戈瑞。由于整个任务期间物理剂量计测量的吸收剂量为5.2厘戈，相对生物效应（RBE）约为2.8。
