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Sato, Tatsuhiko
no journal, ,
In the field of radiation biology, particularly that related to molecular biology, researchers have tried to elucidate the mechanism of radiation effects by discovering something new such as expressions of certain types of gene and protein. On the other hand, "quantification" is more important than "discovery" for connecting such studies to radiation protection and medical physics. Data expressed as a function of certain physical quantities such as absorbed dose and dose rate are desirable for the "quantification", instead of those expressed by two bars (e.g., control and exposure groups) with the discussion on their statistical significance. For example, International Commission on Radiological Protection (ICRP) started to re-evaluate the relative biological effectiveness (RBE) toward to their new fundamental recommendations, and the biological data without analyzing their dose dependence cannot be used in evaluation. It is very elaborate to repeat similar experiments by changing a certain physical quantity, but such effort can make the experimental data more meaningful and important in the field of radiation protection and medical physics.
Kanzaki, Norie; Sakoda, Akihiro; Kataoka, Takahiro*; Yamaoka, Kiyonori*
no journal, ,
no abstracts in English
Tsujimura, Norio
no journal, ,
The UNSCEAR expressed concern in its 2020 report that eye lens dose due to beta particles emitted from airborne radioiodine has not been adequately assessed for the workers during the initial emergency operations after the TEPCO Fukushima Daiichi NPP accident. To address this concern, the author calculated beta Hp(3) and gamma Hp(10) delivered from radioiodine uniformly distributed in the air using the Monte Carlo particle transport code MCNP5, tabulating the conversion factors which relate the air concentration of radioiodines (Bq/cm
) to the relevant dose rate (Sv/s). The radionuclides to be calculated are I-131, Te-132, I-132, and I-133. The assumed exposure conditions are (i) the concentration ratio of airborne radioiodine was I-131: Te-132 (I-132): I-133 = 1: 2.3 :1.1 at noon on March 12, (ii) I-131 equivalent to the effective dose of 100 mSv was acutely inhaled on the same day, and (iii) no respirator masks were used. Under this exposure scenario, the beta Hp(3) calculated based on the radioiodine concentrations was below 0.1 mSv regardless of indoor or outdoor exposure, which was pretty smaller than the recorded gamma Hp(10).
Ishikawa, Ryoya*; Suzuki, Masatoshi*; Kino, Yasushi*; Endo, Satoru*; Nakajima, Hiroo*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Shinoda, Hisashi*; et al.
no journal, ,
In order to investigate the influence on the oxidative stress status by the long-term exposure after the Fukushima Daiichi Nuclear power plant (FNPP) accident, we analyzed oxidative stress markers in liver and bladder of wild Japanese macaques in the ex-evacuation zone. In liver, the concentration of malondialdehyde (MDA) in approximately 70% of the exposed group exceeded the average and SOD activity of the exposed group shifted toward lower within the range indicated in the control group. By contrast, alteration of MDA concentration and SOD activity in bladder was opposite to that shown in liver. We also found that oxidative stress markers changed in the same manner by external and internal exposure. Our data suggested that exposure to low dose/low dose-rate radiation following the FNPP accident may affect the sensitivity to oxidative stress by changing the activity of antioxidant enzymes.
Fujita, Hiroki
no journal, ,
The ICRP has started to review and revise "The 2007 Recommendations of the ICRP". For that purpose, the ICRP has published two papers: Fit for purpose and Areas of research. The purposes of the first paper are to: encourage discussions throughout the radiological protection community and beyond on which areas of the system might gain the greatest benefit from detailed review and refinement; initiate and shape collaborative efforts to examine prioritised areas and develop improvements; and help define the ICRP programme of work for the coming years. The second paper presents the ICRP's vision on "Areas of Research to Support the System of Radiological Protection". In addition, the ICRP organised a digital workshop as an opportunity to engage with its stakeholder community, based on the papers. Similar events will be held in the future. The ICRP symposia will be milestone events in this process. The current status of the review and revision will be shown.