Paulbeck, C. J.*; Sato, Tatsuhiko; Funamoto, Sachiyo*; Lee, C.*; Griffin, K. T.*; Cullings, H. M.*; Egbert, S. D.*; Endo, Akira; Hertel, N. E.*; Bolch, W. E.*
Radiation and Environmental Biophysics, 62(3), p.317 - 329, 2023/08
In our prior study [Radiat Res 192, 538-561 (2019)], we presented a new J45 (Japanese 1945) series of high-resolution phantoms of the adult pregnant female at 8-week, 15-week, 25-week, and 38-week post-conception. In this present study, we extend this work using realistic angular fluences from the DS02 system for up to nine different radiation categories and five shielding conditions. General findings are that the current DS02 fetal dose surrogate overestimates values of fetal organ dose seen in the J45 phantoms towards the cranial end of the fetus, especially in the later stages of pregnancy. This work supports our previous findings that the J45 pregnant female phantom series offers significate opportunities for gestational age-dependent assessment of fetal organ dose without the need to invoke the uterine wall as a fetal organ surrogate.
Domal, S. J.*; Correa-Alfonso, C. M.*; Paulbeck, C. J.*; Griffin, K. T.*; Sato, Tatsuhiko; Funamoto, Sachiyo*; Cullings, H. M.*; Egbert, S. D.*; Endo, Akira; Hertel, N. E.*; et al.
Health Physics, 15 Pages, 2023/00
The RERF Working Group on Organ Dose (WGOD) has established the J45 (Japan 1945) series of high-resolution voxel phantoms, which were derived from the UF/NCI series of hybrid phantoms and scaled to match mid-1940s Japanese body morphometries. In this present study, we present the J45 pregnant female phantoms in both a kneeling and lying posture, and assess the dosimetric impact of these more anatomically realistic survivor models in comparisons to current organ doses given by the DS02 system. For the kneeling phantoms facing the bomb hypocenter, organ doses from bomb source photon spectra were shown to be overestimated by the DS02 system by up to a factor of 1.45 for certain fetal organs and up to a factor of 1.17 for maternal organs. For lying phantoms with their feet in the direction of the hypocenter, fetal organ doses from bomb source photon spectra were underestimated by the DS02 system by factors as low as 0.77 while maternal organ doses were overestimated by up to a factor of 1.38. Results from this study highlight the degree to which the existing DS02 system can differ from organ dosimetry based upon 3D radiation transport simulations using more anatomically realistic models of those survivors exposed during pregnancy while in a kneeling or lying position.
Isotope News, (781), P. 3, 2022/06
The research reactor JRR-3 at the Nuclear Science Research Institute of Japan Atomic Energy Agency resumed its operation in February 2021 for the first time in 10 years. After commissioning, neutron beam experimental apparatus and irradiation facilities were used from July to November, and the operation in 2021 was completed as planned. During this period, Ir-192 and Au-198 were produced and supplied for therapeutic use, and test irradiation for the production of Mo-99 was performed. This is resumption of radioisotope production using nuclear reactors in Japan, which had stopped after the Great East Japan Earthquake. This article introduces future efforts of radioisotope production for medical applications in JRR-3.
Griffin, K. T.*; Sato, Tatsuhiko; Funamoto, Sachiyo*; Chizhov, K.*; Domal, S.*; Paulbeck, C.*; Bolch, W.*; Cullings, H. M.*; Egbert, S. D.*; Endo, Akira; et al.
Radiation and Environmental Biophysics, 61(1), p.73 - 86, 2022/03
To evaluate the potential dosimetry improvements that would arise from their use in a Dosimetry System (DS) at RERF, we have evaluated organ doses in the J45 series using the environmental fluence data for twenty generalized survivor scenarios pulled directly from the current DS. The energy- and angle-dependent gamma and neutron fluences were converted to a phase space source term for use in MCNP6, a modern radiation transport code. Overall, the updated phantom series would be expected to provide dose improvements to several important organs, including the active marrow, colon, and stomach wall (up to 20%, 20%, and 15% impact on total dose, respectively). The impacts on dosimetry were especially significant for neutron dose estimates (up to a two-fold difference) and within organs which were unavailable in the previous phantom series, such as the skin, esophagus, and prostate.
Hokeikyo Nyusu, (68), P. 1, 2021/10
This article introduces resumption of utilization of the research reactor JRR-3 at the Nuclear Science Research Institute, JAEA. JRR-3 resumed its operation in July 2021 for the first time in 10 years and 7 months, after the confirmation of its conformity to the new regulatory requirements established by the Nuclear Regulatory Commission following the accident at the TEPCO's Fukushima Daiichi Nuclear Power Plant in March 2011. JRR-3 is expected to produce many research results in academic and industrial applications as a research center for neutron science in collaboration with the Materials and Life Science Facility (MFL) of the Japan Proton Accelerator Research Complex (J-PARC).
Petoussi-Henss, N.*; Satoh, Daiki; Endo, Akira; Eckerman, K. F.*; Bolch, W. E.*; Hunt, J.*; Jansen, J. T. M.*; Kim, C. H.*; Lee, C.*; Saito, Kimiaki; et al.
Annals of the ICRP, 49(2), p.11 - 145, 2020/10
The age-dependent dose coefficients of organ equivalent doses and effective doses for the member of the public are required to estimate the external dose of the public exposed to radiations from radionuclides in the environment. For this purpose, a computational method to simulate the radiation fields of environmental photon and electron sources in the air, soil, and water has been developed using a particle transport code PHITS in the JAEA, and the organ equivalent doses have been calculated using the human models of newborns, 1-year-old, 5-years-old, 10-years-old, and 15-years-old children, and adults male and female provided by the ICRP. In addition, the nuclide-specific effective dose coefficients have been derived using the skin-dose data and nuclide-decay data provided by the Hanyang University and ICRP, respectively. The data of the dose coefficients are available for dose estimations of not only the Fukushima Daiichi nuclear accident but radiological emergencies which radionuclides are released to the environment.
Sato, Tatsuhiko; Funamoto, Sachiyo*; Paulbeck, C.*; Griffin, K.*; Lee, C.*; Cullings, H.*; Egbert, S. D.*; Endo, Akira; Hertel, N.*; Bolch, W. E.*
Radiation Research, 194(4), p.390 - 402, 2020/10
Owing to recent advances in computational dosimetry tools, it is desirable to update the dosimetry system for the atomic-bomb survivors as it was established by DS02. In the current study, we have investigated the possible impact of introducing not only the J45 phantom series but also various methodological upgrades to the DS02 dosimetry system. It was found that the anatomical improvement in the J45 phantom series is the most important factor leading to potential changes in survivor organ doses. In addition, this study established a series of response functions which allows for the rapid conversion of the unidirectional quasi-monoenergetic photon and neutron fluences to organ doses within the J45 adult phantoms. This system of response functions can be implemented within a revision to the DS02 dosimetry system and used for future updates to organ doses within the Life Span Study of the atomic-bomb survivors.
Norimatsu, Wataru*; Matsuda, Keita*; Terasawa, Tomoo; Takata, Nao*; Masumori, Atsushi*; Ito, Keita*; Oda, Koji*; Ito, Takahiro*; Endo, Akira*; Funahashi, Ryoji*; et al.
Nanotechnology, 31(14), p.145711_1 - 145711_7, 2020/04
We show that boron-doped epitaxial graphene can be successfully grown by thermal decomposition of a boron carbide thin film, which can also be epitaxially grown on a silicon carbide substrate. The interfaces of BC on SiC and graphene on BC had a fixed orientation relation, having a local stable structure with no dangling bonds. The first carbon layer on BC acts as a buffer layer, and the overlaying carbon layers are graphene. Graphene on BC was highly boron doped, and the hole concentration could be controlled over a wide range of 210 to 210 cm. Highly boron-doped graphene exhibited a spin-glass behavior, which suggests the presence of local antiferromagnetic ordering in the spin-frustration system. Thermal decomposition of carbides holds the promise of being a technique to obtain a new class of wafer-scale functional epitaxial graphene for various applications.
Paulbeck, C.*; Griffin, K.*; Lee, C.*; Cullings, H.*; Egbert, S. D.*; Funamoto, Sachiyo*; Sato, Tatsuhiko; Endo, Akira; Hertel, N.*; Bolch, W. E.*
Radiation Research, 192(5), p.538 - 561, 2019/08
An important cohort of the atomic bomb survivors are pregnant females exposed to the photon and neutrons fields at both Hiroshima and Nagasaki, as well as their children who were exposed . In the present study, we present a new J45 (Japanese 1945) series of high-resolution phantoms of the adult pregnant female at 8-week, 15-week, 25-week, and 38-week post-conception. As for the maternal organ doses, the use of organ doses in a non-pregnant female were shown, in general, to overestimate the corresponding organ doses in the pregnant female, with greater deviations seen at later stages of pregnancy. These results demonstrate that the J45 pregnant female phantom series offers the opportunity for significant improvements in both fetal and maternal organ dose assessment within this unique cohort of the atomic bomb survivors.
Griffin, K.*; Paulbeck, C.*; Bolch, W.*; Cullings, H.*; Egbert, S. D.*; Funamoto, Sachiyo*; Sato, Tatsuhiko; Endo, Akira; Hertel, N.*; Lee, C.*
Radiation Research, 191(4), p.369 - 379, 2019/04
Due to computing limitations of the time, only three stylized phantoms were used in DS86 and DS02 to represent the entire Japanese population: an infant, child, and adult. Our study aimed to evaluate the dosimetric impact that should be expected from using an updated and age-expanded RERF phantom series with the survivor cohort. To this end, we developed a new series of hybrid phantoms, based on the Japanese population of 1945, which has greater anatomical realism and improved age resolution than those previously used by RERF. From the photon portion of the spectra, dose differences of up to nearly 25% are expected between the old and new series, while differences of up to nearly 70% are expected from the neutron portion. Overall, our new series of phantoms has shown to provide significant improvements to survivor organ dosimetry, especially to those survivors who were previously misrepresented in body size by their stylized phantom and to those who experienced a highly-directional irradiation field.
Otto, T.*; Hertel, N. E.*; Bartlett, D. T.*; Behrens, R.*; Bordy, J.-M.*; Dietze, G.*; Endo, Akira; Gualdrini, G.*; Pelliccioni, M.*
Radiation Protection Dosimetry, 180(1-4), p.10 - 16, 2018/08
Report Committee 26 of the ICRU proposes a set of operational quantities for radiation protection for external radiation, directly based on effective dose and for an extended range of particles and energies. It is accompanied by new quantities for estimating deterministic effects to the eye lens and the local skin. The operational quantities are designed to overcome the conceptual and technical shortcomings of those presently in use. This paper describes the proposed operational quantities, and highlights the improvements with respect to the present legal monitoring quantities.
Radiation Protection Dosimetry, 175(3), p.378 - 387, 2017/07
The International Commission on Radiation Units and Measurements (ICRU) has been discussing to propose a new system of the operational quantities for external radiations based on protection quantities. The aim of this study is to provide a set of conversion coefficients for use in defining personal dose equivalent for individual monitoring. Fluence-to-effective dose conversion coefficients have been calculated for photons, neutrons, electrons, positrons, protons, muons, pions and helium ions for various incident angles of radiations. The data sets comprise effective dose conversion coefficients for incident angles of radiations from 0 to 90 in steps of 15 and at 180. Conversion coefficients for rotational, isotropic, superior hemisphere semi-isotropic and inferior hemisphere semi-isotropic irradiations are also included. The conversion coefficients are used to define the operational quantity personal dose equivalent which is being considered by ICRU and utilized for the design and calibration of dosemeters.
Hoken Butsuri, 52(1), p.39 - 41, 2017/03
Radiological protection requires the quantification of the extent of exposure of the human body to ionizing radiation. To this end, the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU) developed a dosimetry system consisting of protection quantities and operational quantities. The existing dosimetry system has been successfully used in radiological protection practice and regulations. Nevertheless, the system has some limitations and needs further improvements to consider changes in the fields of radiological protection. ICRP and ICRU have been discussing the issues to propose an alternative system of radiation dosimetry. This presentation overviews recent discussion on the protection quantities and operational quantities by ICRP and ICRU and the proposed dosimetry system for radiological protection.
Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 44 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the -ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10).
Annals of the ICRP, 45(1_suppl.), 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.
Endo, Akira; Hamada, Nobuyuki*
Isotope News, (745), p.42 - 43, 2016/06
ICRP Symposium on Radiological Protection Dosimetry was held in Hongo campus, the University of Tokyo on February 18, 2016. Committee 2 of the International Commission on Radiological Protection (ICRP) is engaged in the development of dose coefficients for the assessment of internal and external radiation exposures; development of reference biokinetic and dosimetric models, and reference data for workers and members of the public. The symposium aimed at reviewing the current work of ICRP and discussing research needed for the ICRP System of radiological protection dosimetry. This article reviews the presentations and discussion in the symposium.
Satoh, Daiki; Furuta, Takuya; Takahashi, Fumiaki; Endo, Akira; Lee, C.*; Bolch, W. E.*
Journal of Nuclear Science and Technology, 53(1), p.69 - 81, 2016/01
To estimate effective doses for the public exposed to external radiation from radioactive cesium (Cs and Cs) deposited on the ground by the Fukushima nuclear accident, we calculate the conversion coefficients for converting activity concentration to effective dose rate by using the Particle and Heavy Ion Transport code System (PHITS). The data were produced from different age groups within the public (newborns; 1-, 5-, 10-, and 15-year-old children; and adults) for the situations in which radioactive cesium is distributed uniformly in the soil over a planar area and at specific depths of 0.0, 0.5, 2.5, 5.0, 10.0, and 50.0 g/cm. On the basis of the results, we also derive the conversion coefficients for exponentially distributed volumetric sources. In addition, we obtain the conversion coefficients that give the effective dose accumulated over the first and second months, the first year, and over a lifetime (50 years) because of the contamination remaining on the ground. These calculations indicate that the conversion coefficients to obtain the effective dose rate are higher for the younger ages compared with adults but do not exceed the ambient dose equivalent rate. Furthermore, we find that the difference between the calculated effective dose rates according to the International Commission on Radiological Protection (ICRP) 1990 and 2007 Recommendations is small (7% maximum) for a ground contamination of radioactive cesium.
Takahashi, Fumiaki; Sato, Kaoru; Endo, Akira; Ono, Koji*; Ban, Nobuhiko*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Yoshitake, Takayasu*; Kai, Michiaki*
Health Physics, 109(2), p.104 - 112, 2015/08
A dosimetry system, named WAZA-ARI, is developed to assess accurately radiation doses to persons from Computed Tomography (CT) examination patients in Japan. Organ doses were prepared to application to dose calculations in WAZA-ARI by numerical analyses using average adult Japanese human models with the Particle and Heavy Ion Transport code System (PHITS). Experimental studies clarified the radiation configuration on the table for some multi-detector row CT (MDCT) devices. Then, a source model in PHITS could specifically take into account for emissions of X-ray in each MDCT device based on the experiment results. Numerical analyses with PHITS revealed a concordance of organ doses with human body size. The organ doses by the JM phantoms were compared with data obtained using previously developed systems. In addition, the dose calculation in WAZA-ARI were verified with previously reported results by realistic NUBAS phantoms and radiation dose measurement using a physical Japanese model. The results implied that analyses using the Japanese phantoms and PHITS including source models can appropriately give organ dose data with consideration of the MDCT device and physiques of typical Japanese adults.
Isotope News, (736), p.34 - 37, 2015/08
Japanese translation of ICRP Publication 116 entitled "Conversion Coefficients for Radiological Protection Quantities for External Radiation Exposures" was published by the Japan Radioisotope Association in March 2015. The book gives fluence to dose conversion coefficients for both effective dose and organ absorbed doses for various types of external exposures, consistent with the 2007 Recommendations of the ICRP. A complete set of conversion coefficients is provided in an accompanying CD in ASCII format and Microsoft Excel software. This article overviews ICRP Publication 116 and its impact to practice of radiation protection.
Sato, Kaoru; Takahashi, Fumiaki; Endo, Akira; Ono, Koji*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Yoshitake, Takayasu*; Ban, Nobuhiko*; Kai, Michiaki*
RIST News, (58), p.25 - 32, 2015/01
The Japan Atomic Energy Agency (JAEA) are now developing WAZA-ARI for improvement of management of exposure doses due to CT examination under the joint research with the Oita University of Nursing and Health Sciences. The trial version of WAZA-ARI has been released on 21 December 2012. In trial version, users can perform dose assessment by using organ dose database based on the average adult Japanese male (JM-103) and female (JF-103) voxel phantoms and a 4 years old female voxel phantom (UFF4). The homepage of WAZA-ARI has been accessed over 1000 times per month and 28421 times by the end of September 2014. We are developing WAZA-ARI version 2 as the extension version of dose calculation functions of WAZA-ARI. WAZA-ARI version 2 will be released by the end of March 2015. In WAZA-ARI version 2. Users can upload dose calculation results to WAZA-ARI version 2 server, and utilize improvement of the dose management of patients and the optimization of CT scan conditions.