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Journal Articles

Dosimetric dependence of ocular structures on eye size and shape for external radiation fields of electrons, photons, and neutrons

Furuta, Takuya; El Basha, D.*; Iyer, S. S. R.*; Correa Alfonso, C. M.*; Bolch, W. E.*

Journal of Radiological Protection, 39(3), p.825 - 837, 2019/09

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Despite large variation of human eye, only one computational eye model has been adopted in almost all the radiation transport simulation studies. We thus adopted a new scalable and deformable eye model and studied the radiation exposure by electrons, photons, and neutrons in the standard radiation fields such as AP, PA, RLAT, ROT, by using Monte Carlo radiation transport code PHITS. We computed the radiation exposure for 5 eye models (standard, large, small, myopic, hyperopic) and analyzed influence of absorbed dose in ocular structures on eye size and shape. Dose distribution of electrons is conformal and therefore the absorbed doses in ocular structures depend on the depth location of each ocular structure. We thus found a significant variation of the absorbed doses for each ocular structure for electron exposure due to change of the depth location affected by eye size and shape. On the other hand only small variation was observed for photons and neutrons exposures because of less conformal dose distribution of those particles.

Journal Articles

A Scalable and deformable stylized model of the adult human eye for radiation dose assessment

El Basha, D.*; Furuta, Takuya; Iyer, S. S. R.*; Bolch, W. E.*

Physics in Medicine and Biology, 63(10), p.105017_1 - 105017_13, 2018/05

 Times Cited Count:3 Percentile:48.33(Engineering, Biomedical)

With recent changes in the recommended annual limit on eye lens exposures to ionizing radiation by International Commission on Radiological Protection, there is considerable interest in predictive computational dosimetry models of the human eye and its various ocular structures. Several computational eye models to date have been constructed for this purpose but they are typically constructed of nominal size and of a roughly spherical shape associated with the emmetropic eye. We therefore constructed a geometric eye model that is both scalable (allowing for changes in eye size) and deformable (allowing for changes in eye shape), and that is suitable for use in radiation transport studies of ocular exposures and radiation treatments of eye disease. As an example, electron and photon anterior-posterior radiation transport with the constructed eye model was conducted and analyzed resultant energy-dependent dose profiles. Due to anterior-posterior irradiation, the energy dose response was shifted to higher energy for a larger-size eye or an axially deformed eye in prolate shape because the structures were located in deeper depth compared to the normal eye.

Journal Articles

Integrating radiation protection criteria for radioactive waste management into remediation procedures in existing exposure situations after a nuclear accident

Sugiyama, Daisuke*; Kimura, Hideo; Tachikawa, Hirokazu*; Iimoto, Takeshi*; Kawata, Yosuke*; Ogino, Haruyuki*; Okoshi, Minoru*

Journal of Radiological Protection, 38(1), p.456 - 462, 2018/03

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Experience after the accident at the Fukushima Daiichi Nuclear Power Station has shown that there is a need to establish radiation protection criteria for radioactive waste management consistent with the criteria adopted for the remediation of existing exposure situations. A stepwise approach to setting such criteria is proposed. Initially, a reference level for annual effective dose from waste management activities in the range 1-10 mSv should be set, with the reference level being less than the reference level for ambient dose. Subsequently, the reference level for annual effective dose from waste management activities should be reduced in one or more steps to achieve a final target value of 1 mSv. The dose criteria at each stage should be determined with relevant stakeholder involvement. Illustrative case studies show how this stepwise approach might be applied in practice.

JAEA Reports

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2015 - March 31, 2016)

Nuclear Emergency Assistance and Training Center

JAEA-Review 2017-011, 54 Pages, 2017/07

JAEA-Review-2017-011.pdf:3.46MB

The Japan Atomic Energy Agency (JAEA) is a designated public institution under the Disaster Countermeasures Basic Act and under the Armed Attack Situations Response Act. Based on these Acts, the JAEA has the responsibility of providing technical support to the national and some local governments in case of a nuclear incident. In case of a nuclear emergency, the Nuclear Emergency Assistance and Training Center (NEAT) dispatches experts of JAEA, supplies the governments with emergency equipment, and gives them technical advice and information. In normal time, NEAT provides various drills/exercises and training courses to nuclear emergency responders. In FY2015, the NEAT accomplished the following tasks: (1) Improvement of hardware and software for technical support activities (2) Human resource development, exercise and training of nuclear emergency responders ; (3) Researches on nuclear emergency preparedness and response, and dissemination of useful information for emergency responders; (4) Arrangements for technical support for aerial monitoring; and (5) Technical contributions to Asian countries on nuclear emergency preparedness and response.

Journal Articles

Operational quantities and new approach by ICRU

Endo, Akira

Annals of the ICRP, 45(1S), p.178 - 187, 2016/06

The protection quantities, equivalent dose in an organ or tissue and effective dose, were developed by ICRP to allow quantification of the extent of exposure of the human body to ionizing radiation to be used for the implementation of the limitation and optimization principles. The body-related protection quantities are not measurable in practice. Therefore, ICRU developed a set of operational dose quantities for use in radiation measurements for external radiations that provide assessment of the protection quantities. ICRU has examined the rationale for operational quantities taking into account the changes in the definitions of the protection quantities in the ICRP 2007 Recommendations. The committee has investigated a set of alternative definitions for operational quantities different to the existing quantities. The major change in the currently favoured set of quantities is the redefinition of the operational quantities for area monitoring from being based on doses at a point in the ICRU sphere to ones based on particle fluence and the relationship to the protection quantities.

JAEA Reports

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2014 - March 31, 2015)

Nuclear Emergency Assistance and Training Center

JAEA-Review 2016-005, 55 Pages, 2016/05

JAEA-Review-2016-005.pdf:3.61MB

The Japan Atomic Energy Agency, JAEA, is a designated public institution under the Disaster Countermeasures Basic Act and under the Armed Attack Situations Response Act. Based on these Acts, the JAEA has the responsibility of providing technical support to the national government and/or local governments in case of nuclear and/or radiological incidents. In order to fulfill the tasks as the designated public institution, the JAEA has established the Emergency Action Plan and the Civil Protection Action Plan. In case of a nuclear/radiological emergency, the Nuclear Emergency Assistance and Training Center (NEAT) dispatches specialists of JAEA, supplies the national government and local governments with emergency equipment and materials, and gives them technical advice and information. In normal time, NEAT provides various exercises and training courses concerning nuclear preparedness and response to emergency responders including the national and local government officers, in addition to the JAEA staff members. The NEAT also researches nuclear emergency preparedness and response, and cooperates with international organizations on the above research theme. In the FY2014, the NEAT accomplished the following tasks: (1) Technical support activities as a designated public institution in cooperation with the national and local governments, (2) Human resource development, exercise and training of nuclear emergency responders for the national and local governments, (3) Researches on nuclear emergency preparedness and response, and release to the public as useful information, (4) Technical contributions to Asian countries on nuclear emergency preparedness and response in collaboration with the international organizations.

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 2; Meanings and features of dose quantities used in radiation protection

Saito, Kimiaki; Yamamoto, Hideaki

Radioisotopes, 63(11), p.519 - 530, 2014/11

This article aims to provide the basic meanings and features of the doses frequently used in the measurements and evaluations of environmental radiation due to the Fukushima Dai-ichi Nuclear Power Plant accident. The following doses are explained and compared: absorbed dose as basic physical quantity; effective dose and equivalent dose for judgment in radiation protection; and ambient dose equivalent $$H^{*}$$(10) and individual dose equivalent $$H$$p(10) for radiation measurements.

Journal Articles

Development of a calculation method for estimating specific energy distribution in complex radiation fields

Sato, Tatsuhiko; Yokoya, Ritsuko; Niita, Koji*

Radiation Protection Dosimetry, 122(1-4), p.41 - 45, 2006/12

 Times Cited Count:39 Percentile:6.22(Environmental Sciences)

Estimation of biological effects due to exposure of HZE particles is one of the key issues in the planning of long-term space missions and heavy ion cancer therapies. Detailed information on the specific energy distributions around their tracks is indispensable in the issue. We therefore calculated the specific energy distributions in liquid water around the tracks of protons and several kinds of heavy ions with energies from 1 MeV/n to 100 GeV/n. The calculations were performed by a Monte Carlo electron track structure simulation code coupled with the Katz's delta-ray production model. An analytical function to reproduce the simulation results has been developed in order to predict the distribution for all kinds of heavy ions with wide energy ranges. By incorporated into the Particle and Heavy Ion Transport code System PHITS, the function enables us to calculate the specific energy distribution in macroscopic matters such as specified organs of astronauts or tumor of patients within a short computational time.

Journal Articles

Development of dose monitoring system applicable to various radiations with wide energy ranges

Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 42(9), p.768 - 778, 2005/09

 Times Cited Count:16 Percentile:24.49(Nuclear Science & Technology)

A new inventive radiation monitor, designated to DARWIN (Dose Assessment system applicable to various Radiations with WIde energy raNges), has been developed for monitoring doses at workspaces of high energy accelerator facilities and on ground. Characteristics of DARWIN were studied by both calculation and experiment. The calculated results indicate that DARWIN gives reasonable estimations of doses at most radiation fields. It was found from the experiment that DARWIN has an excellent property of measuring doses from all particles that significantly contribute to the background dose - photon, muon and neutron with wide energy ranges.

JAEA Reports

Annual report on the activities of Health Physics in JAERI in 2004; April 1, 2004$$sim$$March 31, 2005

Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Safety Division, Kansai; Operation Safety Administration Division, Mutsu

JAERI-Review 2005-028, 232 Pages, 2005/08

JAERI-Review-2005-028.pdf:13.23MB

no abstracts in English

Journal Articles

Simulations of an accelerator-based shielding experiment using the particle and heavy-ion transport code system PHITS

Sato, Tatsuhiko; Sihver, L.*; Iwase, Hiroshi*; Nakashima, Hiroshi; Niita, Koji*

Advances in Space Research, 35(2), p.208 - 213, 2005/06

 Times Cited Count:24 Percentile:14.45(Engineering, Aerospace)

In order to estimate the biological effects of HZE particles, an accurate knowledge of the physics of interaction of HZE particles is necessary. Since the heavy ion transport problem is a complex one, there is a need for both experimental and theoretical studies to develop accurate transport models. RIST and JAERI (Japan), GSI (Germany) and Chalmers (Sweden) are therefore currently developing and bench marking the General-Purpose Particle and Heavy-Ion Transport code System (PHITS). In this paper, we report simulations of an accelerator-based shielding experiment, in which a beam of 1 GeV/n Fe-ions has passed through thin slabs of polyethylene, Al, and Pb at an acceptance angle up to 4&ordm.

JAEA Reports

Annual report on the activities of Health Physics in JAERI in 2003; April 1, 2003$$sim$$March 31, 2004

Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Safety Division, Kansai; Operation Safety Administration Division, Mutsu

JAERI-Review 2004-024, 209 Pages, 2004/11

JAERI-Review-2004-024.pdf:26.17MB

no abstracts in English

Journal Articles

Profile of energy deposition in human body irradiated by heavy ions

Sato, Tatsuhiko; Tsuda, Shuichi; Sakamoto, Yukio; Yamaguchi, Yasuhiro; Niita, Koji*

Journal of Nuclear Science and Technology, 41(Suppl.4), p.287 - 290, 2004/03

Radiological protection against heavy ions has been an essential issue in the planning of long term space missions. We performed Monte Carlo calculations of dose distributions in terms of the linear energy transfer (LET) of ionizing particles using Particle and Heavy Ion Transport code System, PHITS, for incidences of various kinds of heavy ions with energies up to 3 GeV/A. Based on the results, we found that large amounts of energies are imparted by particles with an LET above 10 keV/mm even for the incidences of heavy ions with high energies. This tendency is different from that for high energy hadron incidences, where more than 80% of the total deposited energies are imparted by particles with an LET below 10 keV/mm.

JAEA Reports

Overview of nuclear safety research 2001-2002

Nuclear Safety Research Center Planning and Analysis Division

JAERI-Review 2003-040, 298 Pages, 2004/01

JAERI-Review-2003-040.pdf:24.14MB

JAERl is conducting nuclear safety research primarily at the Nuclear Safety Research Center in close cooperation with the related departments in accordance with the Annual Plan for Nuclear Safety Research issued by the Nuclear Safety Commission. The fields of conducting safety research at JAERl are the engineering safety of nuclear power plants and nuclear fuel cycle facilities, and radioactive waste management as well as advanced technology for safety improvement or assessment. This report summarizes the nuclear safety research activities of JAERI from April 2001 through March 2003.

JAEA Reports

Annual report of the activities of Health Physics in JAERI in 2002; April 1, 2002$$sim$$March 31, 2003

Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Safety Division, Kansai; Operation Safety Administration Division, Mutsu

JAERI-Review 2003-034, 208 Pages, 2003/11

JAERI-Review-2003-034.pdf:13.41MB

no abstracts in English

Journal Articles

Conversion coefficients from fluence to effective dose for heavy ions with energies up to 3 GeV/A

Sato, Tatsuhiko; Tsuda, Shuichi; Sakamoto, Yukio; Yamaguchi, Yasuhiro; Niita, Koji*

Radiation Protection Dosimetry, 106(2), p.137 - 144, 2003/11

 Times Cited Count:19 Percentile:20.88(Environmental Sciences)

Radiological protection against high energy heavy ions has been an essential issue in the planning of long-term space missions. We calculated fluence to effective dose conversion coefficients for heavy ions using the Particle and Heavy Ion Transport code System PHITS coupled with an anthropomorphic phantom of the MIRD5 type. The calculations were performed for incidences of protons and typical space heavy ions with energies up to 3 GeV/A in the isotropic and anterior-posterior irradiations. Based on the results, we propose a simple fitting formula that can predict the effective dose from almost all kinds of space heavy ions below 3 GeV/A within an accuracy of 30%.

JAEA Reports

NuTEC annual report; April l, 2001 - March 31, 2002

Nuclear Technology and Education Center

JAERI-Review 2003-003, 81 Pages, 2003/05

JAERI-Review-2003-003.pdf:3.48MB

This report summarizes the educational activities and related management of the Nuclear Technology andEducation Center (NuTEC) during the 2001 fiscal year. Both Tokyo and Tokai Education Centers have successfully conducted almost all the planned domestic and international training courses. In addition Tokai Education Center has performed the 3nd nuclear supervisor training course and introduced a new course for special nuclear emergency preparedness in response to the legal amendment after the criticality accident. The sum total number of participants was 1,310. The International Technology Transfer Division has not only planned and organized the international training courses, but also taken charge of the 3nd workshop on Human Resource Development in Nuclear Field in Asian and Pasific Region. Various researches have been made to improve the educational program.

JAEA Reports

Annual report of the activities of Health Physics in JAERI in 2001; April 1, 2001 - March 31, 2002

Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Safety Division, Kansai; Operation Safety Administration Division, Mutsu

JAERI-Review 2002-036, 219 Pages, 2002/12

JAERI-Review-2002-036.pdf:15.01MB

no abstracts in English

JAEA Reports

Annual report of the activities of Health Physics in JAERI in 2000; April 1, 2000 - March 31, 2001

Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Safety Division, Kansai; Operation Safety Administration Division, Mutsu

JAERI-Review 2001-041, 221 Pages, 2001/12

JAERI-Review-2001-041.pdf:14.1MB

no abstracts in English

Journal Articles

Compilation of new nuclear decay data files used for dose calculation

Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 38(8), p.689 - 696, 2001/08

 Times Cited Count:4 Percentile:64.35(Nuclear Science & Technology)

no abstracts in English

62 (Records 1-20 displayed on this page)