Yoshimura, Kazuya; Sanada, Yukihisa; Sato, Rina; Nakayama, Mariko*; Tsubokura, Masaharu*
Journal of Radiation Research (Internet), 7 Pages, 2023/00
After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, individual exposure doses to residents have been assessed by many municipalities, governments and research institutes. Various methods including measurements with personal dosimeters and simulations have been used for this evaluation depending on purposes, but the information of assessments and methods has not been systematically organized. A comprehensive review of the knowledge and experiences of individual exposure doses assessments accumulated so far and understanding the characteristics of the assessment methods will be very useful for radiation protection and risk communication, following to governmental policy planning. We reviewed the efforts made by the Japanese government and research institutes to assess radiation doses to residents after the FDNPS accident in Part1. On the other hand, each method of assessing individual exposure doses includes uncertainties and points to be considered for the appropriate assessment. These knowledge and experiences are important for the assessment implementation and applying the assessment results to the governmental policy planning, and are summarized in Part2 of this article.
Suzuki, Gen*; Ishikawa, Tetsuo*; Oba, Takashi*; Hasegawa, Arifumi*; Nagai, Haruyasu; Miyatake, Hirokazu*; Yoshizawa, Nobuaki*
Journal of Radiation Research (Internet), 63(6), p.796 - 804, 2022/11
To elucidate the association between radiation dose and thyroid cancer after the 2011 Fukushima Daiichi Nuclear Power Station (FDNPS) accident, it is essential to estimate individual thyroid equivalent doses (TEDs) to children. In a previous study, we reported a methodology for reconstructing TEDs from inhalation based on individual behavioural survey sheets combined with a spatiotemporal radionuclides database constructed by an atmospheric transport, diffusion, and deposition model (ATDM). In the present study, we further refined our methodology and estimated the combined TEDs from inhalation and ingestion among children in 16 municipalities around the nuclear power station utilizing 3,256 individual whereabouts questionnaire survey sheets. Distributions of estimated TEDs were similar to estimates based on direct thyroid measurements in 1080 children in Iwaki City, Kawamata Town, Iitate Village, and Minamisoma City. Mean TEDs in 1-year-old children ranged from 1.3 mSv in Date City to 14.9 mSv in Odaka Ward in Minamisoma City, and the 95th percentiles varied from 2.3 mSv in Date City to 28.8 mSv in Namie Town. In the future, this methodology can be useful for a case-control study of thyroid cancer after the FDNPS accident.
Kono, Takahiko; Tanaka, Masato*; Tanaka, Hitomi*; Shimo, Michikuni*; Torii, Hiroyuki*; Uno, Kazuko*
Journal of Radiation Protection and Research, 47(3), p.167 - 179, 2022/09
After the accident at the Fukushima Daiichi Nuclear Power Plant, artificial radionuclides such as radioactive cesium and iodine were released into the environment. It caused great anxiety not only in the vicinity of the Fukushima Daiichi Nuclear Power Plant but also in other regions of the world. Some members of the Japan Health Physics Society (JHPS), a leading academic society in Japan in the field of radiation protection, volunteered to establish a website called "Question and Answer about radiation in Daily Life" shortly after the accident to help reduce the residents anxiety about the health effects of radiation. In August 2011, Committee for "Question and Answer about radiation in Daily Life" was established in JHPS, making the website-related activities a responsibility of JHPS. The Q&A website continued to respond to the questions from the general public with expertise and sincerity until February 2013 when the Committee members decided to end the activities because the number of questions received had gradually decreased with the passage of time. This paper aims to introduce the following: the activities of the Q&A website during the two years (2011-2013), the stance chosen for the activities, the information related to the website activities and the analysis of Twitter data. Building on the experience and the knowledge obtained from the activities, it also discusses issues and experiences that can be utilized in the initial response to emergencies for radiation protection experts as well as other fields.
Kataoka, Takahiro*; Ishida, Tsuyoshi*; Naoe, Shota*; Kanzaki, Norie; Sakoda, Akihiro; Tanaka, Hiroshi; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
Journal of Radiation Research (Internet), 63(5), p.719 - 729, 2022/09
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; Sasaki, Keiichi*; et al.
Journal of Radiation Research (Internet), 63(4), p.609 - 614, 2022/07
Electron spin resonance (ESR) dosimetry is one of the most powerful tools for radiation dose reconstruction. The detection limit of this technique using human teeth is reported to be 56 mGy or 67 mGy; however, the absorbed dose of Fukushima residents after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident was estimated to be lower than this detection limit. Our aim is to assess the absorbed radiation dose of children in Fukushima Prefecture after the accident; therefore, it is important to estimate the detection limit for their teeth. The detection limit for enamel of deciduous teeth of Japanese children separated by the mechanical method is estimated to be 115.0 mGy. The density separation method can effectively separate enamel from third molars of Japanese people. As we have collected thousands of teeth from children in Fukushima, the present technique may be useful to examine their external absorbed dose after the FNPP accident.
Sato, Rina; Yoshimura, Kazuya; Sanada, Yukihisa; Sato, Tetsuro*
Journal of Radiation Protection and Research, 47(2), p.77 - 85, 2022/06
After the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, a model was developed to estimate the external exposure doses for residents who were expected to return to their homes after evacuation orders were lifted. However, the model's accuracy and uncertainties in parameters used to estimate external doses have not been evaluated. This study validates the model's accuracy by comparing the estimated effective doses with the measured personal dose equivalents. The personal dose equivalents and life pattern data were collected for 36 adult participants who lived or worked near the FDNPS in 2019. The estimated effective doses correlated significantly with the personal dose equivalents, demonstrating the model's applicability for effective dose estimation. However, the lower value of the effective dose relative to personal dose equivalent indoors could be because the conversion factor from ambient dose equivalent to effective dose did not reflect the actual environment.
Yoshimura, Kazuya; Nakama, Shigeo; Fujiwara, Kenso
Journal of Radiation Protection and Research, 47(1), p.30 - 38, 2022/03
Yokoyama, Sumi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; Ono, Koji*; et al.
Journal of Radiation Protection and Research, 47(1), p.1 - 7, 2022/03
Background: In Japan, new regulations that revise the dose limit for the lens of the eye (the lens), operational quantities, and measurement positions for the lens dose were enforced in April 2021. Based on the international safety standards, national guidelines, the results of the Radiation Safety Research Promotion Fund of the Nuclear Regulatory Authority, and other studies, the Working Group of Radiation Protection Standardization Committee, the Japan Health Physics Society (JHPS) developed a guideline for radiation dose monitoring for the lens. Materials and Methods: The Working Group of the JHPS discussed the criteria of non-uniform exposure and the management criteria set to not exceed the dose limit for the lens. Results and Discussion: In July 2020, the JHPS guideline was published. The guideline consists of three parts: main text, explanations, and 26 questions. In the questions, the corresponding answers were prepared, and specific examples were provided to enable similar cases to be addressed. Conclusion: With the development of guideline on radiation dose monitoring of the lens, radiation managers and workers will be able to smoothly comply with revised regulations and optimise radiation protection.
Sanada, Yukihisa; Yoshimura, Kazuya; Sato, Rina; Nakayama, Mariko*; Tsubokura, Masaharu*
Journal of Radiation Research (Internet), 9 Pages, 2022/00
The evacuation orderareas established due to the accident at the Tokyo Electric Power Company Holdings' (TEPCO) Fukushima Daiichi Nuclear Power Plant (FDNPP) have been reorganized according to the decrease in ambient dose rates and the decontamination progress. The Japanese government decided to decontaminate the difficult-to-return areas and lift the evacuation order by 2030. This radiation protection strategy can be optimized by examining emergency exposure situations to date and the existing exposure after the accident. This article reviews the methods that can determine the individual radiation doses of residents who should return to their homes when the evacuation order is lifted in the specific reconstruction reproduction base area and the difficult-to-return areas outside this base area and summarizes the points to be considered when implementing these methods. In Part 1 of this article, we review the efforts made by the Japanese government and research institutes to assess radiation doses to residents after the FDNPP accident.
Sanada, Yukihisa; Ishida, Mutsushi*; Yoshimura, Kazuya; Mikami, Satoshi
Journal of Radiation Protection and Research, 46(4), p.184 - 193, 2021/12
no abstracts in English
Shimada, Kazumasa; Kai, Michiaki*
Journal of Radiation Protection and Research, 46(3), p.83 - 97, 2021/09
[Background] The lifetime risk of lung cancer incidence owing to radiation for non-smokers is overestimated because the average cancer baseline among a population including smokers is used. In recent years, the generalized multiplicative (GM) excess relative risk (ERR) model has been developed in the life span study of atomic bomb survivors to consider the joint effect of radiation and smoking. Based on this background, the issues of radiation risk assessment considering smoking will be discussed in this paper in 2 parts. [Materials and Methods] Part 1: We proposed a simple method of estimating the baseline risk for non-smokers using current smoking data. We performed sensitivity analysis on baseline risk estimation to discuss the birth cohort effects of birth year effect and smoking history. Part 2: We applied the GM ERR model for Japanese smokers to calculate lifetime attributable risk (LAR). We also performed a sensitivity analysis with other ERR models (e.g., simple additive (SA) ERR model). [Results] Part 1: The lifetime baseline risk (LBR) for non-smokers were 54% (44% - 60%) or males and 24% (18% - 29%) for females, which were lower than the LBRs for all adults including smokers. Part 2: When comparing the LAR between the SA ERR model and the GM ERR model, if the radiation dose was 200 mGy or less, the difference between these ERR models was within the standard deviation of the LAR owing to the uncertainty of the smoking information.
Yoshida, Hiroko*; Kuroda, Yujiro*; Kono, Takahiko; Naito, Wataru*; Sakoda, Akihiro
Journal of Radiation Protection and Research, 46(3), p.134 - 142, 2021/09
The Japan Health Physics Society established a task group on "Public Understanding after the Fukushima Daiichi Nuclear Power Plant Accident" in the 2018-2019 fiscal year. This task group collected and analyzed various activities that had been made for promotion of public understanding since the Fukushima accident, and then discussed some issues such as expert's roles. This paper outlines a panel session for this task group held at the 53rd Annual Meeting of the Japanese Health Physics Society (Online). This session consisted of (1) reporting what the task group achieved, (2) having comments by two designated experts in the fields of sociology and ethics, (3) making a panel discussion with three representatives from the task group and the two designated speakers, and (4) summarizing this session by a rapporteur.
Andresz, S.*; Sakoda, Akihiro; Ha, W.-H.*; Kabrt, F.*; Kono, Takahiko; Sez Muoz, M.*; Nusrat, O.*; Papp, C.*; Qiu, R.*; Bryant, P.*
Journal of Radiation Protection and Research, 46(3), p.143 - 150, 2021/09
The Young Generation Network (YGN) was officially established as part of the International Radiation Protection Association (IRPA) in the spring of 2018. Since then, it has been dedicated to a variety of activities to promote communication, collaboration and professional development of students and young professionals in the area of radiation protection and its allied fields. This article reports our recent activities from the middle of 2018 to the beginning of 2021, with highlights on some important events: (1) Joint JHPS-SRP-KARP Workshop of Young Generation Network (December 2019 in Japan); (2) Contribution to Nuclear Energy Agency Workshop on Optimization - Rethinking the Art of Reasonable (January 2020 in Portugal); (3) Survey on the impact of COVID-19 on radiation protection among IRPA YGN members (March 2020); (4) Contribution to IRPA15 (January-February 2021; online). The discussion and insight obtained from each activity are also summarized. The IRPA YGN will aim to achieve its on-going activities and continue to follow the ways paved in the Strategic Agenda and despite the challenges raised by the COVID-19 pandemic. Namely, running an international survey (for example, on the usage of social media in radiation protection, and on the long-term consequences of the COVID-19 pandemic), engaging national YGNs, extending the network, finding new relationships with networks with an interest in the young generation and participation in (remote) events will be aspired for.
Chang, W.*; Koba, Yusuke*; Furuta, Takuya; Yonai, Shunsuke*; Hashimoto, Shintaro; Matsumoto, Shinnosuke*; Sato, Tatsuhiko
Journal of Radiation Research (Internet), 62(5), p.846 - 855, 2021/09
With the aim of developing a revaluation tool of treatment plan in carbon-ion radiotherapy using Monte Carlo (MC) simulation, we propose two methods; one is dedicated to identify realistic-tissue materials from a CT image with satisfying the well-calibrated relationship between CT numbers and stopping power ratio (SPR) provided by TPS, and the other is to estimate dose to water considering the particle- and energy-dependent SPR between realistic tissue materials and water. We validated these proposed methods by computing depth dose distribution in homogeneous and heterogeneous phantoms composed of human tissue materials and water irradiated by a 400 MeV/u carbon beam with 8 cm SOBP using a MC simulation code PHITS and comparing with results of conventional treatment planning system (TPS). Our result suggested that use of water as a surrogate of real tissue materials, which is adopted in conventional TPS, is inadequate for dose estimation from secondary particles because their production rates cannot be scaled by SPR of the primary particle in water. We therefore concluded that the proposed methods can play important roles in the reevaluation of the treatment plans in carbon-ion radiotherapy.
Kataoka, Takahiro*; Shuto, Hina*; Naoe, Shota*; Yano, Junki*; Kanzaki, Norie; Sakoda, Akihiro; Tanaka, Hiroshi; Hanamoto, Katsumi*; Mitsunobu, Fumihiro*; Terato, Hiroaki*; et al.
Journal of Radiation Research (Internet), 62(5), p.861 - 867, 2021/09
Sakoda, Akihiro; Ishimori, Yuu; Kanzaki, Norie; Tanaka, Hiroshi; Kataoka, Takahiro*; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
Journal of Radiation Research (Internet), 62(4), p.634 - 644, 2021/07
It is held that the skin dose from radon progeny is not negligibly small and that introducing cancer is a possible consequence under normal circumstances, while there are a number of uncertainties in terms of related parameters such as activity concentrations in air, target cells in skin, skin covering materials, and deposition velocities. Meanwhile, an interesting proposal emerged in that skin exposure to natural radon-rich thermal water as part of balneotherapy can produce an immune response to induce beneficial health effects. The goal of the present study was to obtain generic dose coefficients with a focus on the radon progeny deposited on the skin in air or water in relation to risk or therapeutic assessments. We thus first estimated the skin deposition velocities of radon progeny in the two media based on data from the latest human studies. Using the optimized velocities, skin dosimetry was then performed under different assumptions regarding alpha-emitting source position and target cell (i.e., basal cells or Langerhans cells). Furthermore, the impact of the radon progeny deposition on effective doses from all exposure pathways relating to "radon exposure" was assessed using various possible scenarios. It was found that in both exposure media, effective doses from radon progeny inhalation are one to four orders of magnitude higher than those from the other pathways. In addition, absorbed doses on the skin can be the highest among all pathways when the radon activity concentrations in water are two or more orders of magnitude higher than those in air.
Okuno, Hiroshi; Sato, Sohei; Kawakami, Takeshi; Yamamoto, Kazuya; Tanaka, Tadao
Journal of Radiation Protection and Research, 46(2), p.66 - 79, 2021/06
The nuclear accident at the Fukushima Daiichi Nuclear Power Station (NPS) of Tokyo Electric Power Company (TEPCO) was a typical one of the disastrous damages that induced evacuation of the residents around the NPS, which was triggered by the hugest earthquake and associated tsunami. This paper summarized early responses of the Japan Atomic Energy Agency (JAEA), especially of its Nuclear Emergency Assistance and Training Center (NEAT) to the off-site emergencies associated with the TEPCO's Fukushima Daiichi NPS. The paper addressed activities of emergency preparedness of the NEAT before 2011 in relevant to the TEPCO's Fukushima Daiichi NPS, the situation of the NEAT on March 11, 2011, and its early responses to the related off-site emergencies including those caused by the accident at the TEPCO's Fukushima Daiichi NPS. The paper also discussed issues associated with complex disasters.
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Shuto, Hina*; Yano, Junki*; Naoe, Shota*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
Journal of Radiation Research (Internet), 62(2), p.206 - 216, 2021/03
Radon inhalation activates antioxidative functions in mouse organs, thereby contributing to inhibition of oxidative stress-induced damage. Therefore, in this study, we evaluated the redox state of various organs in mice following radon inhalation. Mice inhaled radon at concentrations of 2 or 20 kBq/m for 1, 3, or 10 days. The relationship between antioxidative function and oxidative stress was evaluated by principal component analysis (PCA) and correlation coefficient compared with control mice subjected to sham inhalation. These findings suggested that radon inhalation altered the redox state in organs, but that the characteristics varied depending on the redox state in organs.
Sakoda, Akihiro; Murakami, Shoichi*; Ishimori, Yuu; Horai, Sawako*
Journal of Radiation Research (Internet), 61(2), p.207 - 213, 2020/03
Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Sato, Tetsuro*; Seki, Akiyuki; Sanada, Yukihisa; Wainwright-Murakami, Haruko*; et al.
Journal of Radiation Protection and Research, 44(4), p.128 - 148, 2019/12