Comparison of biological measurement and physical estimates of space radiation in the International Space Station
Kayo Yoshida, Megumi Hada, Akane Kizu, Kohei Kitada, Kiyomi Eguchi-Kasai, Toshiaki Kokubo, Takeshi Teramura, Sachiko Yano, Hiromi Suzuki, Hitomi Watanabe, Gen Kondoh, Aiko Nagamatsu, Premkumar B. Saganti, Francis A. Cucinotta, Takashi Morita
Abstract
ES cells showed no differences in chromosomal aberrations between the ground control and ISS exposures. However, we detected an increase of chromosome aberrations in radio-sensitized histone H2AX heterozygous-deficient mouse ES cells and found that the rate of increase against the absorbed dose was 1.54-fold of proton irradiation at an accelerator. On the other hand, we estimated the quality factor of space radiation as 1.48 ± 0.2. using formulas of International Commission of Radiation Protection (ICRP) 60. The relative biological effectiveness (RBE) observed from our experiments (1.54-fold of proton) was almost equal (1.04-fold) to the physical estimation (1.48 ± 0.2). It should be important to clarify the relation between biological effect and physical estimates of space radiation. This comparative study paves a way to reveal the complex radiation environments to reduce the uncertainty for risk assessment of human stay in space.