著者
浜田 信行 ロイ E. ショア ローレンス T. ダウアー
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.53, no.2, pp.47-64, 2018 (Released:2018-09-13)
参考文献数
60
被引用文献数
1

For over four decades, a linear nonthreshold (LNT) model has been used for radiation protection purposes. In the United States of America, the National Council on Radiation Protection and Measurements (NCRP) established Scientific Committee 1-25 in 2015 to prepare a commentary to review recent epidemiologic data from studies with low doses or low dose rates and from the Life Span Study of atomic-bomb survivors to determine whether these epidemiologic studies broadly support the LNT model. In May 2018, NCRP published Commentary No. 27 “Implications of recent epidemiologic studies for the linear nonthreshold model and radiation protection”, noting that the ongoing development of science requires a constant reassessment of prior and emerging evidence to assure that the approach to radiation protection is optimal, even if not necessarily perfect. Based on the current epidemiological data, NCRP concluded that the LNT model (perhaps with excess risk estimates reduced by a dose and dose rate effectiveness factor) should continue to be utilized for radiation protection purposes. The Commentary will be used to support the work of NCRP Council Committee 1 who are charged to develop current radiation protection guidance for the United States, ultimately updating and expanding the basic radiation protection recommendations of NCRP Report No. 116 published in 1993. This review provides an outline and summary of the key points of NCRP Commentary No. 27.
著者
林田 敏幸 佐々木 洋 浜田 信行 立崎 英夫 初坂 奈津子 赤羽 恵一 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.52, no.2, pp.88-99, 2017 (Released:2017-07-29)
参考文献数
54

In March 2011, the accident occurred at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company. During recovery from critical situations, the radiation dose for some emergency workers exceeded the effective dose limit recommended for an emergency situation. A month after the accident, the International Commission on Radiological Protection issued a statement on tissue reactions recommending significant reduction of the equivalent dose limit to the lens of the eye. Many radiation workers will need to be involved in treatment of water contaminated with radionuclides, fuel debris retrieval, and decommissioning of reactors for a long period of time. Thus, the optimized radiation control in the fields, exposure reduction, prevention of tissue reactions, and reduction of stochastic risks for workers becomes necessary. This paper discusses issues in relation to radiation protection of the ocular lens in such recovery workers, from the viewpoint of radiation exposure of workers, its management, manifestations and mechanisms of the lens effects.
著者
藤通 有希 小佐古 敏荘 吉田 和生 浜田 信行
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.48, no.2, pp.86-96, 2013 (Released:2014-03-06)
参考文献数
57
被引用文献数
3 1 1

The International Commission on Radiological Protection (ICRP) has classified radiation cataract as tissue reactions (formerly known as deterministic effects or non-stochastic effects) for which a threshold dose exists, and recommended an equivalent dose limit for the lens of the eye to prevent vision-impairing cataracts. A recommended occupational dose limit has been 150 mSv/year predicated on the threshold of >8 Sv since the 1980 Brighton Statement, but was drastically lowered by the 2011 Seoul Statement to 20 mSv/year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. Such a new limit was included immediately in the Interim Edition of General Safety Requirements Part 3 of the International Atomic Energy Agency. In contrast, a dose limit of 15 mSv/year for members of the public has not been changed since the 1990 Recommendations. This paper considers the impacts of a new limit focusing on conformity with cancer risk management, the necessity of the public dose limit in planned exposure situations and the occupational dose limit in emergency exposure situations. Potential issues arising from its implementation shall also be discussed especially in terms of the compensation problem and the possibility of exceeding a dose limit in interventional cardiologists.
著者
浜田 信行 吉永 信治
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.53, no.3, pp.136-145, 2018 (Released:2018-11-27)
参考文献数
66

Ionizing radiation has long been indispensable in medicine. Such medical exposures can broadly be divided into two categories, namely, therapeutic exposures and diagnostic exposures. On one hand, therapeutic exposures generally occur at high dose and/or high dose rate, in which health effects of main concern are tissue reactions (formally called deterministic effects) and second cancer. Of these, mounting epidemiological evidence for tissue reactions has attracted particular attention to circulatory disease and cataracts. Diagnostic exposures, on the other hand, occur at relatively low dose and/or low dose rate, where cancer is the major health effect of concern. Epidemiological evidence from diagnostically exposed populations is still subject to uncertainties in dose (e.g., lack of individual doses) and potential biases (e.g., confounding by indication and reverse causation), which render direct risk estimation of diagnostic exposures unreasonable. This raises the need for the extrapolation from epidemiological evidence in other populations exposed to high dose and/or high dose-rate radiation. From radiation protection viewpoints, recent discussions include individual risk estimation, and individual radiation responses. This review paper provides a brief overview of recent topics in epidemiology and risk estimation for medical exposures.
著者
浜田 信行
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.52, no.2, pp.77-87, 2017 (Released:2017-07-29)
参考文献数
37
被引用文献数
3

In April 2011, the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens of the eye. Since then, discussions toward implementation of such a revised dose limit into national law have been made in various countries. In the United States of America (US), the National Council on Radiation Protection and Measurements (NCRP) established Scientific Committee 1-23 (SC 1-23) in January 2014 to provide guidance on whether existing dose limits for the ocular lens should be changed in the US, to which the author of this paper served as Consultant. In January 2017, NCRP published Commentary No. 26 “Guidance on radiation dose limits for the lens of the eye” which was prepared by SC 1-23. With this Commentary, NCRP now recommends reducing the occupational dose limit for the lens from equivalent dose of 150 mSv/year to absorbed dose of 50 mGy/year along with the use of relative biological effectiveness value for high linear energy transfer radiation. This review provides an outline of this Commentary.
著者
赤羽 恵一 飯本 武志 伊知地 猛 岩井 敏 大口 裕之 大野 和子 川浦 稚代 立崎 英夫 辻村 憲雄 浜田 信行 藤通 有希 堀田 豊 山崎 直 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.49, no.3, pp.153-156, 2014 (Released:2015-07-18)
参考文献数
14
被引用文献数
3

A brief review is given of the history and methodology of external dosimetry for the lens of the eye. Under the 1989 revision to domestic radiological protection regulations, the concept on the effective dose equivalent and the dose limit to the lens of the eye (150 mSv/y) both introduced in the ICRP 1977 recommendations has changed nationwide the external monitoring methodology in non-uniform exposure situations to the trunk of a radiological worker. In such situations, which are often created by the presence of a protective apron, the worker is required to use at least two personal dosemeters, one worn on the trunk under the apron and the other, typically, at the collar over the apron. The latter dosemeter serves the dual purpose of providing the dose profile across the trunk for improved effective dose equivalent assessment and of estimating the dose to lens of the eye. The greater or appropriate value between Hp(10) and Hp(0.07), given by the dosemeter, is generally used as a surrogate of Hp(3) for recording the dose to the lens of the eye. The above-mentioned methodology was continued in the latest 2001 revision to the relevant regulations.
著者
赤羽 恵一 飯本 武志 伊知地 猛 岩井 敏 大口 裕之 大野 和子 川浦 稚代 立崎 英夫 辻村 憲雄 浜田 信行 藤通 有希 堀田 豊 山崎 直 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.50, no.2, pp.128-137, 2015 (Released:2016-01-09)
参考文献数
8
被引用文献数
2

While the revised dose limit for the lens of the eye was presented by the International Commission on Radiological Protection (ICRP), the dose measurement standards for the lens of the eye have been discussed in the International Organization for Standardization (ISO). In the International Basic Safety Standards of International Atomic Energy Agency (IAEA), a new ICRP dose limit of the lens of the eye was included, and a technical document was published as a guidance on the implications of the new dose limit for the lens of the eye for occupational radiation protection. By the International Radiation Protection Association (IRPA) Task Group on Implementation of Revised Dose Limits to the Lens of the Eye, the opinions for the new ICRP dose limit for the lens of the eye are investigated for the member states. In this paper, the progress of discussion in these organizations is reported.
著者
赤羽 恵一 飯本 武志 伊知地 猛 岩井 敏 大口 裕之 大野 和子 川浦 稚代 立崎 英夫 辻村 憲雄 浜田 信行 藤通 有希 堀田 豊 山崎 直 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.50, no.1, pp.76-89, 2015 (Released:2015-12-18)
参考文献数
52
被引用文献数
2 1

For many Japanese radiation workers in the medical, nuclear and other industrial fields, the equivalent dose of the lens of the eye will be sufficiently lower than the new ICRP dose limit. However, the dose of the lens of the eye for medical staff members who are engaged in interventional radiology and cardiology may exceed the new ICRP dose limit, especially when they are exposed closely to higher scatter radiation for a long time. In addition, the radiation dosimetry and radiation protection for emergency and recovery workers in the Fukushima Daiichi Nuclear Power Plant (FNPP1) are important issues. Thus gathering information related to the radiation dose and protection for Japanese radiation workers is important to a discussion regarding implementation of the new ICRP dose limit for the lens of the eye for Japanese regulations and planning radiation dose reduction measures. In this paper, recent studies and issues regarding radiation exposure and protection in the medical, nuclear and other industrial fields, as well as for emergency and recovery workers in the FNPP1 were summarized.
著者
赤羽 恵一 飯本 武志 伊知地 猛 岩井 敏 大口 裕之 大野 和子 川浦 稚代 立崎 英夫 辻村 憲雄 浜田 信行 藤通 有希 堀田 豊 山崎 直 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.50, no.1, pp.67-75, 2015 (Released:2015-12-18)
参考文献数
40
被引用文献数
3

The International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU) have been defined operational quantities and protection quantities. Dose limits have been also recommended by the ICRP using protection quantities. These quantities and some related values for main radiation such as photons, electrons, and neutrons, are summarized in this article with some historical considerations. The ICRP indicated conversion coefficients for the lens of the eye as absorbed dose per fluence as protection quantities. Equivalent dose is not used because a protection quantity that uses radiation weighting factors is not intended to be calculated for tissue reactions. So far, the ICRP has not indicated a specific RBE value for cataract formation. Operational quantities are used for measurements. There have been three types of phantoms, namely a slab phantom, a reduced phantom, and a cylindrical phantom, but none of them has been definitely recommended for the lens of the eye by the ICRP or the ICRU. Although conversion coefficients to personal dose equivalent, Hp(3), for electrons have been recommended, no other conversion coefficients to personal dose equivalent for the lens of the eye has been indicated by the ICRP or the ICRU. However, there have been several studies described personal dose equivalent. Ambient dose equivalent, H*(3), and directional dose equivalent, H'(3,a), have been indicated in several limited conditions by the ICRP and the ICRU. These status are overviewed in this article.
著者
赤羽 恵一 飯本 武志 伊知地 猛 岩井 敏 大口 裕之 大野 和子 川浦 稚代 立崎 英夫 辻村 憲雄 浜田 信行 藤通 有希 堀田 豊 山崎 直 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.49, no.3, pp.145-152, 2014 (Released:2015-07-18)
参考文献数
52
被引用文献数
4

In April 2011, the International Commission on Radiological Protection (ICRP) issued the statement on tissue reactions. This stimulated interest in many countries. The Expert Committee on Radiation Protection of the Lens of the Eye was established in the Japanese Health Physics Society, and in April 2013, started discussion about the international developments and recent studies related to the dosimetry of the lens of the eye. This committee now publishes the interim report consisting of parts I-VI. Of these, this Part I overviews the structure of the eye and lens, cataract types and the scientific evidence of its new dose threshold and equivalent dose limit newly recommended by the ICRP.
著者
赤羽 恵一 飯本 武志 伊知地 猛 岩井 敏 大口 裕之 大野 和子 川浦 稚代 立崎 英夫 辻村 憲雄 浜田 信行 藤通 有希 堀田 豊 山崎 直 横山 須美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.49, no.4, pp.171-179, 2014 (Released:2015-12-18)
参考文献数
21
被引用文献数
3

Many studies have been internationally reported as part of projects regarding the radiation exposure for the lens of the eye of medical staff members under various conditions, methods of dosimetry and development of dosimeters for the lens of the eye. Recently conducted studies include the Retrospective Evaluation of Lens Injuries and Dose (RELID) of the International Atomic Energy Agency, Occupational Cataracts and Lens Opacities in interventional Cardiology (O’CLOC) study in France, Optimization of Radiation Protection of Medical Staff (ORAMED) project in European countries, and a 20-year prospective cohort study among US radiologic technologists. Given the newly implemented dose limit for the lens of the eye by the International Commission on Radiological Protection (ICRP), we summarized these studies as the necessary information for reconsideration of the Japanese dose limit for the lens of the eye. In addition, this article also covers the exposures for the lens of the eye of clean-up workers in the Chernobyl accident as shown in ICRP Publication 118 and the results of a hearing survey with specialists of the Academy of Medical Science of Ukraine.
著者
藤通 有希 小佐古 敏荘 吉田 和生 浜田 信行
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.48, no.2, pp.97-103, 2013 (Released:2014-03-06)
参考文献数
25
被引用文献数
2 1

Radiation cataract has been classified as tissue reactions (formerly known as deterministic effects or non-stochastic effects) with a threshold dose. In 1984, the International Commission on Radiological Protection (ICRP) suggested the threshold dose of >8 Sv for vision-impairing cataracts in highly fractionated or protracted exposures. Such a threshold was used to recommend an occupational dose limit for the lens of 150 mSv/year in 1990 and 2007, but was reduced to 0.5 Sv in 2011 for all exposure scenarios irrespective of the rate of dose delivery. New threshold was determined on the basis of the limited human evidence, with various hypotheses not supported by the present knowledge of biological mechanisms. Examples of untested hypotheses include: (a) radiation cataract is a tissue reaction; (b) radiation damage to the large number of cells acts as a triggering event for radiation cataract; (c) detectable minor opacities progress into vision-impairing cataracts with time; and (d) the lower the dose, the longer the latency. This paper discusses the issues behind the scientific basis for the new threshold, and provides directions for future epidemiological and biological studies to establish the reasonably modeled dose-response relationship for radiation cataract.