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Yokoyama, Sumi*; Hamada, Nobuyuki*; Tsujimura, Norio; Kunugita, Naoki*; Nishida, Kazutaka*; Ezaki, Iwao*; Kato, Masahiro*; Okubo, Hideki*
International Journal of Radiation Biology, 99(4), p.604 - 619, 2023/04
Times Cited Count：1 Percentile：22.69(Biology)In April 2011, the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens. Such a new occupational lens dose limit has thus far been implemented in many countries, and there are extensive discussions toward its regulatory implementation in other countries. In Japan, discussions in the Japan Health Physics Society (JHPS) began in April 2013 and in Radiation Council in July 2017, and the new occupational lens dose limit was implemented into regulation in April 2021. To share our experience, we have published a series of papers summarizing situations in Japan: the first paper based on information available by early 2017, and the second paper by early 2019. This paper (our third paper of this series) aims to review updated information available by mid-2022, such as regarding regulatory implementation of the new occupational lens dose limit, recent discussions by relevant ministries based on the opinion from the council, establishment process of safety and health management systems, the JHPS guidelines on lens dose monitoring and radiation safety, voluntary countermeasures of the licensees, development of lens dose calibration method, and recent studies on exposure of the lens in nuclear workers and biological effect on the lens.
Oka, Toshitaka; Takahashi, Atsushi*
Hoshasen Kagaku (Internet), (110), p.13 - 19, 2020/10
The article depicts how to estimate the external exposure dose for wild animals using electron spin resonance (ESR) spectroscopy. The relationship between the CO
radical intensity and the absorbed dose, that is, dose response curve of tooth enamel of Japanese macaque was observed, and the detection limit of our method was estimated. The estimated detection limit of 33.5 mGy is comparable to the previously reported detection limit for human molar teeth. The external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined using this dose response curve. The estimated external exposure dose were ranged between 45 mGy to 300 mGy.
Furuta, Hiroshige*; Tsujimura, Norio; Nishide, Akemi*; Kudo, Shinichi*; Saigusa, Shin*
Radiation Protection Dosimetry, 189(3), p.371 - 383, 2020/05
Times Cited Count：4 Percentile：45.45(Environmental Sciences)Furuta, Takuya
Igaku Butsuri, 37(3), p.177 - 180, 2017/00
Gel dosimeters are gelated aqueous solutions of radiosensitive substances and useful tools to visualize three-dimensional dose distribution of radiations. A study which uses gel dosimeters to quantify the dose distribution in biological samples is explained. In this study, the measured distribution was compared with the simulation result of PHITS to check the accuracy of Monte Carlo simulation in particle therapy situations. The comparison shows that the measured complex distal edge structure of the dose distribution reflecting the particle transport in inhomogeneous biological sample was reproduced by simulation with a precision of 2 mm difference. The result also shows that gel dosimeters are powerful tools to visualize three-dimensional dose distribution and have potential to be used for various purposes such as quality assurance of treatment beams as well as accuracy check of simulations.
Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya; Momose, Takumaro
JPS Conference Proceedings (Internet), 11, p.070008_1 - 070008_6, 2016/11
Hiroki, Akihiro; Yamashita, Shinichi*; Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa
Nuclear Instruments and Methods in Physics Research B, 365(Part B), p.583 - 586, 2015/12
Effects of liner energy transfer (LET) and dose rate on the optical property of polymer gel dosimeters were investigated. The dosimeter prepared by using a radiation-crosslinked hydroxypropyl cellulose gel and methacrylate monomers such as 2-hydroxyethyl methacrylate and nonaethylene glycol dimethacrylate showed the color change from colorless to white with the He, C, Fe ions irradiation. Absorbance of the irradiated dosimeters increased with the dose up to 10 Gy. The absorbance of the dosimeters at the same total dose decreased with increasing dose rate in the range of 0.1 to 6.8 Gy/min. The absorbance decreased in order of He, C, Fe ions, which was in agreement with a change of LET. The increase in LET affected the decrease in the number of polymerization initiator such as OH radical and hydrated electron, resulting in the reduction of the absorbance of the dosimeters.
Japan Atomic Energy Agency; National Institute of Radiological Sciences*
JAEA-Review 2015-007, 50 Pages, 2015/10
JAEA-Review-2015-007.pdf:3.2MB
The review of the evacuation area due to the accident of TEPCO Fukushima Daiichi Nuclear Power Station has completed and the deregulation has begun in some regions. The authors started this research in order to contribute to the understanding of individual dose that is assumed after the return of the residents. Measurements and evaluation using personal dosemeters were conducted at the typical living locations in the area where the evacuation orders are ready to be lifted and the residence restriction area. So the relationship between air dose and personal dose equivalent there was demonstrated observationally and experimentally. In addition, the estimation of the residents' individual doses in the pattern of their social lives expected after returning home.
Hiroki, Akihiro; Yamashita, Shinichi*; Taguchi, Mitsumasa
Journal of Physics; Conference Series, 573(1), p.012028_1 - 012028_4, 2015/01
Times Cited Count：4 Percentile：79.08(Engineering, Biomedical)Polymer gel dosimeters based on radiation-crosslinked hydroxypropyl cellulose gel were prepared, which comprised 2-hydroxyethyl methacrylate (HEMA) and polyethylene glycol dimethacrylate (9G) as less toxic monomers and tetrakis (hydroxymethyl) phosphoniumu chloride (THPC) as an antioxidant. The dosimeters exposed to 
Co 
-rays became cloudy at only 1 Gy. The irradiated dosimeters were optically analyzed by using a UV-vis spectrophotometer to evaluate dose response. Absorbance of the dosimeters linearly increased in the dose range from 0 to 10 Gy. The dose sensitivity increased with increasing 9G concentration. The dosimeter with 2 wt% HEMA, 3 wt% 9G, and 0.16 wt% THPC exhibited about 0.04 Abs Gy
of the dose sensitivity. The dose sensitivity of the dosimeters was also enhanced by increment in THPC, reached about 0.06 Abs Gy at 0.40 wt% THPC.
Yamamoto, Hideaki; Yoshizawa, Michio; Murakami, Hiroyuki; Momose, Takumaro*; Tsujimura, Norio*; Kanai, Katsuta*; Cruz-Suarez, R.*
Radiation Protection Dosimetry, 125(1-4), p.88 - 92, 2007/07
Times Cited Count：0 Percentile：0.01(Environmental Sciences)The purpose of this paper is to discuss the results of the third intercomparison exercise of external radiation dosimetry organized under the Regional Cooperative Agreement (RCA) in the East Asia region of the International Atomic Energy Agency (IAEA). Twenty five laboratories from 16 member states participated in the exercise. Japan Atomic Energy Research Institute (JAERI) and Japan Nuclear Cycle Development Institute (JNC) arranged the standard irradiation of the participants' dosimeters. The results of the measurements of the irradiated dosimeters for the determination of external doses were satisfactory for all participants, demonstrating good performance in their external dosimetry.
Hakoda, Teruyuki; Hanaya, Hiroaki; Kaneko, Hirohisa; Miyashita, Atsumi; Kojima, Takuji
Radioisotopes, 54(6), p.161 - 168, 2005/06
no abstracts in English
Saegusa, Jun; Tanimura, Yoshihiko; Yoshizawa, Michio
Proceedings of 11th International Congress of the International Radiation Protection Association (IRPA-11) (CD-ROM), 8 Pages, 2004/05
Relationships between dosemeter readings and the true dose equivalents at various workplaces were analyzed. From the analysis, it was shown that depending on the types of dosemeters, there exist a suitable calibration field, and the field differs by the difference of response characteristics of dosemeters. For the precise estimation of dose equivalent, it is important that measurement is carried out under the careful considerations of the difference between neutron spectrum at workplace and at calibration field, as well as the improvement of response characteristics of the dosemeters.
Hakoda, Teruyuki; Sunaga, Hiromi; Takizawa, Haruki; Hirota, Koichi; Kojima, Takuji
Radioisotopes, 53(2), p.59 - 69, 2004/02
no abstracts in English
Endo, Akira
Hoken Butsuri, 38(4), p.308 - 317, 2003/12
no abstracts in English
Lee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
Materials Science Forum, 433-436, p.761 - 764, 2003/08
The possibility of applying p-channel SiC MOSFET to dosimeter was investigated. The Source and Drain of SiC MOSFET was formed Al ion implantation at 800 
C and annealing at 1800 C for 1 min in Ar. The gate oxide was fabricated using pyrogenic oxidation. Al electrodes of source and drain is formed Al evaporation and sintering at 850 C for 5 min in Ar. Gamma-ray irradiation to the MOSFETs was doned at the rate of 1MR/h at room temperature. As the result, the change of threshold voltage by irradiation is explained to be K
D
, where K and n are constants.
Obara, Kenjiro; Yagi, Toshiaki; Yokoo, Noriko*; Shibanuma, Kiyoshi
JAERI-Tech 2003-035, 107 Pages, 2003/03
JAERI-Tech-2003-035.pdf:9.45MB
no abstracts in English
Takahashi, Fumiaki; Yamaguchi, Yasuhiro
Radiation Risk Assessment Workshop Proceedings, p.71 - 78, 2003/00
Conversion from tooth enamel dose to organ doses against external photon exposure were studied in order to develop a method that can retrospectively estimate organ doses by the Electron Spin Resonance (ESR) dosimetry using tooth samples. Monte Carlo calculations using EGS4 code were performed to obtain dose to tooth enamel and organ doses by using a modified MIRD-type phantom. The Electron Spin Resonance (ESR) dosimetry using tooth samples and dose measurements using thermo-luminescence dosimeters (TLDs) were also carried out to examine dose to teeth region with a realistic physical phantom. A Voxel-type phantom was constructed from CT images of the physical phantom. Monte Carlo calculations with the Voxel-type phantom were performed to verify the results of the experiments and enamel doses calculated by use of the modified MIRD-type phantom. The obtained data are to be useful for the retrospective assessment of individual dose in past exposure events by the ESR dosimetry with tooth enamel.
Takahashi, Fumiaki; Yamaguchi, Yasuhiro; Iwasaki, Midori*; Miyazawa, Chuzo*; Hamada, Tatsuji*; Saito, Kimiaki
Journal of Nuclear Science and Technology, 39(9), p.964 - 971, 2002/09
Times Cited Count：6 Percentile：39.54(Nuclear Science & Technology)Conversion from tooth enamel dose to organ doses was analyzed to establish a method of retrospective individual dose assessment against external photon exposure by the Electron Spin Resonance (ESR) dosimetry. Dose to tooth enamel was obtained by Monte Carlo calculations using a modified MIRD-type phantom. The calculated tooth enamel doses were verified by measurements with thermo-luminescence dosimeters inserted in a physical head phantom. Energy and angular dependences of tooth enamel dose were compared with those of other organ doses. Additional Monte Carlo calculations were performed to study the effects of human model on the tooth enamel dose with a voxel-type phantom, which was based on CT images of the physical phantom. The data derived with the modified MIRD-type phantom were applied to convert from tooth enamel dose to organ doses against external photon exposure in a hypothesized field, where scattered radiations were taken into account. The results indicated that energy distribution of photons incident to a human body should be required to evaluate precisely individual dose by the ESR dosimetry using teeth.
Takahashi, Fumiaki; Yamaguchi, Yasuhiro; Saito, Kimiaki; Iwasaki, Midori*; Miyazawa, Chuzo*; Hamada, Tatsuji*; Funabiki, Jun*
Journal of Nuclear Science and Technology, 39(Suppl.2), p.1314 - 1317, 2002/08
An analysis of dose to tooth enamel was carried out to develop a method that can predict the organdose and effective dose by the Electron Spin Resonance (ESR) dosimetry using teeth for external photon exposure. Absorbed dose to tooth enamel were obtained with Monte Carlo calculations using EGS4 code with a mathematical human model, which has a newly defined teeth-part. Experiments were also carried out to investigate the dose at the tooth area with a physical head phantom. The calculated doses to tooth enamel were, however, less than the measured doses with the TLDs for the case of photon incidence from the back of a human body. Then, a computational human model, called a “Voxel (Volume-pixel) type" phantom was constructed based upon a computed topography (CT) image of the physical head phantom used in the experiments.The additional Monte Carlo calculations were performed to verify the results in the experiments with the EGS4 in conjunction with user's code UCPIXEL and the Voxel type phantom.
Obara, Kenjiro
Genshiryoku eye, 48(2), p.46 - 48, 2002/02
no abstracts in English
Saegusa, Jun; Yoshizawa, Michio; Tanimura, Yoshihiko; Yoshida, Makoto
Radioisotopes, 51(1), p.26 - 33, 2002/01
no abstracts in English
