 |
 |  |
 |
|
| |
 |
| Reports on Overseas' Conferences and Meetings |
|
| | |
| |
Report on 53rd Annual Meeting of the Health Physics
Society, American Conference of Radiological Safety |
| Naoki Matsuda, Center for Frontier Life Sciences |
The annual meeting of the Health Physics Society provides a wide variety of topics of radiation safety, including radiation dosimetry, radiation biology, medical radiation exposure, risk communication, and emergency preparedness, to its members in the practice of their profession in radiation protection and management. Among 275 papers presented in oral and poster sessions, only three papers were submitted from Japan. This would be explained by a specific condition of radiation protection in the U.S. as well as the upcoming international meeting (IRPA12) in Buenos Aires in October that many Japanese are expected to participate.
In the U.S. where military force is armed with nuclear weapons and is combating against terrorism, `radiation risk control` was underway in a different manner from Japan. In case of radiation terrorism such a dirty bomb attack, it is absolutely necessary for the citizens to be informed about the results from hazard assessment based on the accurate radiation monitoring and on the global meteorological/ geographical databases. The modeling tools and health physics codes for this purpose are developed, released, and introduced to local community’s response organizations. The community-based hazard assessment seems beneficial even in Japan when radiation accident occurs in transportation of radioactive materials and in a nuclear power plant. On the contrary, as one of the radiation accidents that would not be the case in Japan, the U.S. experienced 32 nuclear weapon accidents that occurred between 1950 and 1980, involving the release of weapons grade plutonium. Furthermore, software applications are developed and used for the estimation of human response, including decrement and lethality of soldiers, to simultaneous ionizing radiation, blast, and thermal insults and for the prediction of casualties from protracted radiation exposure. The leading edge of the radiation biology is made use of by the practical military health physics in this way. The early estimation and protection against deterministic effects of radiation are mainly considered here so that stochastic effects are out of the scope.
However, the Society looks sensitive enough to the increase in medical radiation exposure where stochastic effects are the major concern. According to the draft report on the ionizing radiation exposure of the U.S. population by the NCRP (National Council on Radiation Protection and Measurement) which will be released in over 20 years after the previous one published in 1987, the radiation exposure from diagnostic medical procedures (47.8%) is now as great as the exposure to background radiation (48.8%) averaged over the population. The effective dose from medical exposure is now estimated as 6.4mSv/year, showing drastic increase from 3.6mSv/year in 1987. The exposure from CT examinations accounts for more than half of this increase. For these reasons, in the opening plenary session of the meeting, issues regarding CT scan dose estimates and communicating risk with the patients were extensively discussed.
Papers on risk- and crisis-communications were also presented, mainly in a special session “Radiation Accidents and Incidents – Lessons Learned”. From the famous accident at the Three Mile Island nuclear power plant, the news media spokesman for the federal government during the initial weeks of the crisis indicated that effectiveness of risk communication depends on credibility, accuracy, timeliness and completeness. To provide communications techniques and advice based on proven risk and crisis communications strategies as well as radiological scenarios for emergency responders, the guidebook named “Communicating Radiation Risks” is edited and published by the U.S. Environmental Protection Agency. Regarding radiation risk perception by general public, S.M. Becker, a social psychologist, reviewed research and real-world experience with psychological issues in radiological and nuclear incidents. Moreover, what is perceived as “safe” varies widely even among a group of radiation professionals. When they were asked what they consider as a “safe” one-time dose of radiation for themselves and their children, the major answer obtained was 10mSv (consists 26% of total respondents) for adults and both 1mSv and 5mSv (21% each) for children. However, the highest and the lowest dose in all respondents were markedly different as great as 1000-fold.
Ten cases for the internal contamination in academic institutions were found between 1978 and 1995 in the U.S. Among them, the radiation safety officer of MIT reviewed the experience of a criminal intake of P-32 occurred in 1995. According to the report (NUREG-1535) by the Nuclear Regulation Council, the estimated intake radioactivity ranges between 19 and 29MBq, which corresponds to approximately 50mSv of internal exposure. Although no additional case following these accidents was reviewed in detail, the internal contamination by I-125 occurred at Brown University in 1998, reported as PNO-1-98-052 closely resembles to the case at Miyazaki University in 2007, in terms of a motive for the crime, a modus operandi, and an estimated internal exposure dose.
Overall, papers presented in the meeting by certified health physicists (CHP), radiation safety officers, medical doctors and scientists covered a wider range of radiation safety control compared to similar meetings in Japan. Together with getting to know a specific condition of radiation protection in the U.S., this participation was highly beneficial and informative for me and my colleagues because we are in charge of risk management at radiation facilities. The papers presented by the Nagasaki University Global COE Program were as follows;
Miura M, Morita N, Takao H, Yoshida M, Matsuda N
Analysis of Radiation Risk Perception by University Faculties and Students in Nagasaki.
Morita N, Takamura N, Yamashita S, Shimasaki T, Yoshida M, Matsuda N
Use of a Whole Body Counter in Radiation Risk Management for University Faculties and Students. |
|
|
| |
|
| |
| |
|
