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Ishikawa, Tetsuo*; Matsumoto, Masaki*; Sato, Tatsuhiko; Yamaguchi, Ichiro*; Kai, Michiaki*
Journal of Radiological Protection, 38(4), p.1253 - 1268, 2018/12
Times Cited Count：7 Percentile：58.07(Environmental Sciences)The current knowledge on internal dose estimation and its health effect were reviewed in this paper. The goals were to discuss the uncertainty of current dose coefficients, to compare the effects of external and internal exposures, and to review recent epidemiological studies. Radionuclides focused on in this study were caesium-137 (
Cs), caesium-134 (
Cs), and iodine-131 (
I), which primarily contributed to internal effective thyroid doses after the Fukushima Dai-ichi Nuclear Power Station accident. Current knowledge suggests that the risk of internal exposure could be generally the same as or less than that of external exposure, when they are compared at the same effective dose.
Shinohara, Ayaka*; Hanaoka, Hirofumi*; Sakashita, Tetsuya*; Sato, Tatsuhiko; Yamaguchi, Aiko*; Ishioka, Noriko*; Tsushima, Yoshito*
Annals of Nuclear Medicine, 32(2), p.114 - 122, 2018/02
Times Cited Count：8 Percentile：44.01(Radiology, Nuclear Medicine & Medical Imaging)Radionuclide therapy with low-energy auger electron emitters could potentially provide high anti-tumor efficacy while keeping normal organs toxicity low. In this study, we evaluated the usefulness of auger electron emitter 
I and compared it with beta-emitter I for tumor treatment in 2D and 3D cell culture models. The computer simulation model for 2D and 3D cell culture were constructed, and the absorbed radiation dose of I or I in each model were calculated by using a Monte Carlo simulation code (PHITS). The therapeutic effect of I was comparable to that of I in 2D model, but the efficacy was inferior to that of I-MIBG in 3D model, since crossfire effect is negligible and the homogeneous distribution of radionuclide was insufficient.
Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Yamaguchi, Yasuhiro
Radiation Protection Dosimetry, 126(1-4), p.501 - 505, 2007/08
Times Cited Count：4 Percentile：31.41(Environmental Sciences)A new inventive radiation dose monitor, designated as DARWIN (Dose monitoring system Applicable to various Radiations with WIde energy raNges), has been developed for real-time monitoring of doses in workspaces and surrounding environments of high energy accelerator facilities. DARWIN satisfies the following features: (1) capable of monitoring doses from neutrons, photons and muons with wide energy ranges - from thermal energy to 1 GeV, 150 keV to 100 MeV, and 1 MeV to 100 GeV, respectively, (2) high sensitivity and precision - more than 10 times as sensitive as conventional moderator-based survey instruments for neutrons, (3) easy to operate with a simple user-interface, and (4) light weighted for movability. The details of the features will be described at the presentation, together with the results of the calibrations performed in several accelerator facilities.
Sato, Tatsuhiko; Niita, Koji*; Iwase, Hiroshi*; Nakashima, Hiroshi; Yamaguchi, Yasuhiro; Sihver, L.*
Radiation Measurements, 41(9-10), p.1142 - 1146, 2006/10
Times Cited Count：30 Percentile：87.57(Nuclear Science & Technology)The applicability of PHITS to the shielding design of spacecrafts was examined by comparing calculated neutron spectra and doses for astronauts in the Space Shuttle with the corresponding experimental data. The agreements between the data were quite satisfactory, especially for the neutron spectra, which have been barely reproduced by other studies. We therefore concluded that PHITS has a great possibility of playing an important role in the design study of spacecrafts.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*; Ishibashi, Kenji*
Journal of Nuclear Science and Technology, 43(7), p.714 - 719, 2006/07
Times Cited Count：34 Percentile：89.07(Nuclear Science & Technology)Response functions of a BC501A liquid organic scintillator for neutrons up to 800MeV have been measured at the heavy-ion medical accelerator of the National Institute of Radiological Sciences, Japan. A thick graphite target was bombarded with 400-MeV/u C ions and 800-MeV/u Si ions to produce high-energy neutrons whose kinetic energy was determined by the time-of-flight method. The measured response functions were compared with the results calculated using SCINFUL-QMD code, which experimentally verified the accuracy of SCINFUL-QMD up to 800MeV. This work will contribute to extending the energies measurable with our new radiation dose-monitoring system (DARWIN), which is based on the BC501A scintillator.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Matsufuji, Naruhiro*; Sato, Shinji*; Takada, Masashi*
NIRS-M-192, p.224 - 225, 2006/05
Light output of liquid organic scintillator NE213 has been measured for proton, deuteron, triton, 
He nucleus and alpha particle. A thick graphite target was bombarded with 400-MeV/u C ions to the produce charged particles. Time-of-flight method was adopted to determine the kinetic energy of the charged particles. Light output for proton was also measured using mono-energy beams of 100 and 160 MeV. The experimental results gave a new database of light output.
Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Yamaguchi, Yasuhiro
Journal of Nuclear Science and Technology, 42(9), p.768 - 778, 2005/09
Times Cited Count：17 Percentile：73.49(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.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*; Ishibashi, Kenji*
AIP Conference Proceedings 769, p.1680 - 1683, 2005/05
Response function of liquid organic scintillators is essential to derive the accurate neutron spectrum. Experimental data above 100 MeV, however, are very scarce. The existing Monte Carlo codes, SCINFUL and CECIL, are often used for estimation of the response function instead of the experimental data. These codes are known to reproduce well the response function for incidences below 100 MeV. Unfortunately, the codes are not applicable to the calculation in the higher energy region. In order to determine the response functions above 100 MeV, a new Monte Carlo code, designated as SCINFUL-QMD, has been developed. In the comparison with the experimental data up to 800 MeV, the validation of SCINFUL-QMD was confirmed. The results of SCINFUL-QMD agreed with the experimental data better than those of other calculation codes.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*
NIRS-M-180, p.263 - 264, 2005/05
Response functions of NE213 liquid organic scintillator have been measured to develop a dose assessment method for high-energy neutrons. Spallation reactions by 800 MeV/u Si ions and 400 MeV/u C ions incident into thick carbon targets were utilized for the production of high-energy neutrons. Kinetic energies of neutrons were determined by the time-of-flight (TOF) method. 
-ray and charged particle events were eliminated from experimental data in off-line analysis. The measured response functions were used for validation of the simulation by the SCINFUL-QMD code, which is utilized for calculation of the G-function that converts the scintillator response to neutron dose. It was found from the results that SCINFUL-QMD has a good ability to reproduce the response functions.
Li+ZnS(Ag) sheetSato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takahashi, Fumiaki
Radiation Protection Dosimetry, 110(1-4), p.255 - 261, 2004/09
Times Cited Count：8 Percentile：48.81(Environmental Sciences)For monitoring of neutron doses in high-energy accelerator facilities, we have developed a neutron-monitor detector applicable to energies from the thermal energy to 100 MeV. The detector is composed of a cylindrical (12.7 cm in diameter and 12.7 cm in length) liquid organic scintillator BC501A covered with Li+ZnS(Ag) sheets. Characteristics of this phoswitch-type detector were studied experimentally in moderated neutron fields of 
Am-Be and 
Cf sources, and in quasi-monoenergetic neutron fields of 40 and 70 MeV. It was found from the experiments that the detector is enough sensitive to both thermal and fast neutrons, and has an excellent property of pulse-shape discrimination between them. We concluded, therefore, that the detector can be used for monitoring of neutron doses over a wide energy range from the thermal to 100 MeV.
Endo, Akira; Kim, E.; Yamaguchi, Yasuhiro; Sato, Tatsuhiko; Yoshizawa, Michio; Tanaka, Susumu; Nakamura, Takashi; Rasolonjatovo, A. H. D.*
Journal of Nuclear Science and Technology, 41(Suppl.4), p.510 - 513, 2004/03
no abstracts in English
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.
Sato, Tatsuhiko; Tsuda, Shuichi; Sakamoto, Yukio; Yamaguchi, Yasuhiro; Niita, Koji*
Radiation Protection Dosimetry, 106(2), p.145 - 153, 2003/11
Times Cited Count：14 Percentile：66.94(Environmental Sciences)For the purposes of radiological protection, it is extremely important to analyse profiles of energy deposition in the human body irradiated by high energy hadrons. We therefore performed Monte Carlo calculations of dose distributions in terms of the LET of ionising particles using a newly developed particle transport code PHITS for incidences of neutrons, protons and pions with energies from 100 MeV to 200 GeV. Based on our calculations, we found that more than 80% and more than 90% of the total deposited energies are imparted by particles with a LET below 10 keV/mm for the irradiations of neutrons and the charged particles, respectively. These results are expected to be useful in micro-dosimetric analysis for elucidating the dependence of the biological effects of irradiation on the incident radiation type and energy.
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：75.79(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%.
Sato, Tatsuhiko; Fujii, Katsutoshi; Murayama, Takashi; Sakamoto, Yukio; Yamaguchi, Yasuhiro; Sato, Yukio*; Soma, Nobuyuki*; Fujisaki, Noboru*; Hara, Satoshi*; Aikawa, Yukio*; et al.
JAERI-Tech 2002-028, 20 Pages, 2002/03
JAERI-Tech-2002-028.pdf:5.01MB
Tokyo Fire Department developed an armored car against radiation accidents. Dose attenuation factors of the radiation shields had been determined by a simple estimation, and a more precise evaluation was required. By request from Tokyo Fire Department, a precise evaluation of the dose attenuation factor was carried out. The evaluation was done by a Monte Carlo radiation transport simulation code MCNP4B. Benchmark experiments using neutron and gamma ray sources were also performed for ensuring the evaluation method. As a result, it was found out that doses of neutron and gamma ray were attenuated to approximately 10% and 25% by the thickest shield, respectively. These values were close to the ones which had already obtained by the simple estimation.
Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Yamaguchi, Yasuhiro
no journal, ,
A new inventive radiation dose monitor, designated as DARWIN (Dose monitoring system Applicable to various Radiations with WIde energy raNges), has been developed for real-time monitoring of doses in workspaces and surrounding environments of high energy accelerator facilities. DARWIN is composed of a phoswitch-type scintillation detector, which consists of liquid organic scintillator BC501A coupled with ZnS(Ag) scintillation sheets doped with 6Li, and a data acquisition system based on a Digital-Storage-Oscilloscope. The details of its features will be described at the presentation, together with the results of its calibrations performed in several accelerator facilities.
Endo, Akira; Sato, Tatsuhiko; Satoh, Daiki; Shikaze, Yoshiaki; Tanimura, Yoshihiko; Saegusa, Jun; Tsutsumi, Masahiro; Yamaguchi, Yasuhiro; Kaneko, Hirohisa; Oda, Keiji*; et al.
no journal, ,
no abstracts in English
(Ce) airborne detector and shielded HPGe detector inside a vehicleMalins, A.; Ochi, Kotaro; Sanada, Yukihisa; Yamaguchi, Ichiro*; Sato, Tatsuhiko
no journal, ,
Nanayama, Futoshi*; Yamaguchi, Tatsuhiko*; Nakanishi, Toshimichi; Tsuji, Tomohiro*; Ikeda, Michiharu*; Kondo, Yasuo*; Miwa, Michiko*; Sugiyama, Shinji*; Kimura, Kazunari*
no journal, ,
The characteristics of the post-LGM incised valley fills and the depositional sequence were examined the SKM core collected in the Sukumo coastal lowland, where is expected to huge seismic subsidence due to the Nankai Trough great earthquakes. Our sedimentological, radiocarbon dating and paleoenvironmental results are as bellows. Sediments of the SKM core clearly show a succession influenced by post-glacial sea level change. The Matsuda River incised valley was formed in LGM and filled by fluvial sand and gravels in late Pleistocene. After the postglacial transgression, sea level reached -30 m (a.s.l.) at 9.8 ka and the incised valley changed to an estuary environment. The sea level continued to rise and it became an inner bay mud bottom environment, and reaching a maximum water depth was at 7.5 ka. The 7.3 ka Kikai caldera eruption in southern Kyushu caused heavy K-Ah ash fall in southwestern Shikoku, and then large-scale lahars frequently occurred immediately after the ash fall because of the vicinity of volcanic source. After ash fall, the K-Ah secondary sediments rapidly deposited on the inner bay environment and caused forced regression. After 7.0 ka, the growth of the delta became active ahead of the other regions, which may be due to the large K-Ah ash fall. At 5 ka, the sea level reached + 2.5 m (a.s.l.) estimated by the Sukumo midden and this altitude is recognized as the Holocene marine limit in this area. The information on relative sea level change during the past 10000 years has revealed that the Sukumo Bay area has not subsided due to seismic crustal deformation.
Yamaguchi, Tatsuhiko*; Tsuji, Tomohiro*; Nanayama, Futoshi*; Nakanishi, Toshimichi; Ikeda, Michiharu*; Kondo, Yasuo*; Miwa, Michiko*; Hamada, Yohei*
no journal, ,
Shikoku Island is situated 150 km northwest of the Nankai trough that has developed in response to the convergence of the subducting Philippine Sea Plate and overriding Eurasian Plate. This tectonism causes deformation of the island, megathrust earthquakes, and tsunamis. Shikoku Island experiences coseismic and interseismic deformation. The middle Holocene tectonics of the island are still poorly understood. Relative sea-level (RSL) changes indicated by coastal sediments potentially record seismic uplift and subsidence. To infer RSL changes between 8 and 4 cal. kyr BP, we studied Holocene ostracode assemblages from the SKM drill core in Sukumo, southwest Shikoku Island (Tsuji et al., 2018, JpGU, MIS11-P19), and from six cores in the northern part of the island (Yasuhara et al., 2005, Palaeo3; Yasuhara and Seto, 2006, Paleontol. Res. 10). To estimate paleo-water depth and RSL, we employed the ostracode assemblages and modern analog technique. The SKM core is composed of conglomerate, ash, and mud chiefly. Its geological age was examined, using the 
C dating method (Nakanishi et al., 2019, Radiocarbon). The differences in RSL were identified across the island, possibly due to convergence of the Philippine Sea Plate.
