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Journal Articles

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Plant, 1; Laboratory study on the dosemeter position and the shielding effect of full face mask respirators

Hoshi, Katsuya; Yoshitomi, Hiroshi; Aoki, Katsunori; Tanimura, Yoshihiko; Tsujimura, Norio; Yokoyama, Sumi*

Radiation Measurements, 134, p.106304_1 - 106304_5, 2020/06

 Times Cited Count:3 Percentile:43.05(Nuclear Science & Technology)

In FY 2017, the Japanese Nuclear Regulatory Agency (NRA) established the Radiation Safety Research Promotion Fund for funding projects on nuclear safety regulation, and adopted the two-year research project entitled "Study on standard eye lens monitoring, suitable dose management and radiation protection for nuclear and medical workers". The study is a two-phase study: a laboratory study on the eye lens dosemeter's characteristics to photons, and a field study executed at actual workplaces at Fukushima Daiichi Nuclear Power Station. This paper summarizes the results of the first-phase study, which was designed to clarify the eye lens dosemeter positioning and the shielding effect of full face mask respirators used at the station. No marked difference was observed in readings of the dosemeters attached on the different positions on the head phantom. Two types of full face mask respirators provided insignificant shielding effect for photons of 83 keV to 662 keV.

Journal Articles

PARaDIM; A PHITS-based Monte Carlo tool for internal dosimetry with tetrahedral mesh computational phantoms

Carter, L. M.*; Crawford, T. M.*; Sato, Tatsuhiko; Furuta, Takuya; Choi, C.*; Kim, C. H.*; Brown, J. L.*; Bolch, W. E.*; Zanzonico, P. B.*; Lewis, J. S.*

Journal of Nuclear Medicine, 60(12), p.1802 - 1811, 2019/12

 Times Cited Count:12 Percentile:77.26(Radiology, Nuclear Medicine & Medical Imaging)

Voxel human phantoms have been used for internal dose assessment. More anatomically accurate representation become possible for skins or layer tissues owing to recent developments of advanced polygonal mesh-type phantoms and thus internal dose assessment using those advanced phantoms are desired. However, the Monte Carlo transport calculation by implementing those phantoms require an advanced knowledge for the Monte Carlo transport codes and it is only limited to experts. We therefore developed a tool, PARaDIM, which enables users to conduct internal dose calculation with PHITS easily by themselves. With this tool, a user can select tetrahedral-mesh phantoms, set radionuclides in organs, and execute radiation transport calculation with PHITS. Several test cases of internal dosimetry calculations were presented and usefulness of this tool was demonstrated.

Journal Articles

Application of voxel phantoms and Monte Carlo method to whole-body counter calibrations

Kinase, Sakae; Takagi, Shunji*; Noguchi, Hiroshi; Saito, Kimiaki

Radiation Protection Dosimetry, 125(1-4), p.189 - 193, 2007/07

 Times Cited Count:16 Percentile:74.03(Environmental Sciences)

In the Japan Atomic Energy Research Institute (JAERI), a calculation code -UCWBC code- for whole-body counter calibrations using voxel phantoms has been developed as an EGS4 Monte Carlo user code. To validate the UCWBC code for calibrating whole-body counters in JAERI, response functions and counting efficiencies of a p-type high-purity Ge semiconductor detector used for the whole-body counter were evaluated for a water-filled block-shape phantom by the UCWBC code and were measured by experiments. Furthermore, counting efficiencies of the Ge semiconductor detector for the male and female voxel phantoms developed in JAERI were evaluated in the photon energy range 60-1836 keV by the UCWBC code in order to examine the differences between the counting efficiencies for voxel phantoms. In conclusion, it was found that the response functions and counting efficiencies of the Ge semiconductor detector by the UCWBC code for the water-filled block-shape phantom are in good agreement with measured data. The UCWBC code was validated by the comparisons.

Journal Articles

Development of three kinds of tissue substitutes for a physical phantom in neutron dosimetry

Tsuda, Shuichi; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 42(10), p.877 - 887, 2005/10

 Times Cited Count:2 Percentile:18.41(Nuclear Science & Technology)

Three kinds of tissue substitutes were synthesized in order to develop a physical phantom for neutron dosimetry. The optimal elemental compositions and densities were determined using a Monte Carlo simulation method, based on absorbed dose distributions of neutrons of a few MeV in various materials. The characteristics of the synthesized tissue substitutes were verified by absorbed dose measurements using monoenergetic neutron sources and a $$^{252}$$Cf neutron source. It was found that the developed tissue substitutes, NAN-, HAI- and HONE-JAERI, have tissue equivalence to actual tissues within 10 % accuracy for neutrons in most of common fast neutron fields.

Journal Articles

Measurement of neutron and $$gamma$$-ray absorbed doses inside human body in criticality accident situations using phantom and tissue-equivalent dosimeters

Sono, Hiroki; Kojima, Takuji; Soramasu, Noboru*; Takahashi, Fumiaki

JAERI-Conf 2005-007, p.315 - 320, 2005/08

Personal dosimeters provide a fundamental evaluation of external exposures to human bodies in radiation accidents. The dose distribution inside the body, which is needed to estimate the exposures from a result of personal dosimetry, has been evaluated mostly by computational simulations, while experimental data to verify the simulations are not sufficiently supplied, in particular, in criticality accident situations. For the purpose of obtaining the experimental data on external exposures inside the body, a preliminary experiment on criticality accident dosimetry was carried out at the Transient Experiment Critical Facility (TRACY) using a human phantom and tissue-equivalent dosimeters. The neutron and $$gamma$$-ray absorbed doses inside the phantom could be satisfactorily measured by the combined use of an alanine dosimeter and a thermoluminescent dosimeter made of enriched lithium tetra borate. The doses measured in and on the phantom were regarded as reasonable in dose level and distribution by comparison with the doses measured in the free air.

Journal Articles

Application of EGS4 code to evaluation of specific absorbed fractions and S values for internal dosimetry

Kinase, Sakae

KEK Proceedings 2005-3, p.292 - 297, 2005/06

The EGS4 code was used for evaluating the absorbed fraction per unit mass of the target organ-specific absorbed fraction (SAF)- and the mean absorbed dose to the target organ per unit cumulated activity in the source organ (S value) for internal dosimetry. The SAFs and S values were evaluated on a mathematical phantom (MIRD 5 type phantom) and Japanese adult voxel phantoms (Otoko and Onago phantoms) developed at the Japan Atomic Energy Research Institute (JAERI). The evaluated SAFs and S values were compared with several published data in order to demonstrate the use of the EGS4 code for the internal dosimetry and investigate the influence of certain parameters, such as the organ masses, on SAFs and S values. It was demonstrated that the EGS4 code is useful in the evaluation of the SAFs and S values for the internal dosimetry. It was also found that the SAFs and S values for organ self-absorption depend on the organ masses and would be affected by differences in the structure of the human body.

Journal Articles

Examination for neutron dose assessment method from induced sodium-24 in human body in criticality accidents

Takahashi, Fumiaki; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 42(4), p.378 - 383, 2005/04

 Times Cited Count:2 Percentile:18.41(Nuclear Science & Technology)

Experiments were made to verify a dose assessment method from activated sodium in body in criticality accidents. A phantom containing sodium chloride solution was irradiated in the Transient Experiment Critical Facility to simulate activation of sodium. Monte Carlo calculations were performed to obtain quantitative relation between the activity of induced Na-24 and neutron dose in the phantom. In the previous work, conversion coefficients from specific activity of induced Na-24 to neutron dose had been analyzed with the MCNP-4B code concerning neutron spectra at some hypothesized configurations. One of the prepared coefficients was applied to evaluate neutron dose from the measured activity. The estimated dose agreed with the dose analyzed by the Monte Carlo calculation in the present study within an acceptable uncertainty, which is indicated by the IAEA. In addition, the dose calculated with the prepared coefficient was close to the result measured with dosimeters. These results suggest that the prepared coefficients can be applied to dose assessments from induced Na-24 in body.

JAEA Reports

Calculation of age-dependent dose conversion coefficients for radionuclides uniformly distributed in air

Tran, V. H.; Satoh, Daiki; Takahashi, Fumiaki; Tsuda, Shuichi; Endo, Akira; Saito, Kimiaki; Yamaguchi, Yasuhiro

JAERI-Tech 2004-079, 37 Pages, 2005/02

JAERI-Tech-2004-079.pdf:5.02MB

no abstracts in English

Journal Articles

Calibration of epithermal neutron beam intensity for dosimetry at JRR-4

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Sakurai, Yoshinori*; Kobayashi, Toru*

Proceedings of 11th World Congress on Neutron Capture Therapy (ISNCT-11) (CD-ROM), 15 Pages, 2004/10

To carry out the boron neutron capture therapy (BNCT) using the epithermal neutron, the epithermal neutron beam intensity was measured by using $$^{197}$$Au reaction rate activated on the resonance absorption peak (4.9eV). Two scaling factors, which are the reactor power calibration factor and the calculation/experiment (C/E) scaling factor, are necessary in order to correct with the simulation and actual irradiation experiment. First, an optimum detector position was investigated using MCNP code. The result of MCNP calculation showed that the influence of subject placed at the collimator was below 1% when the detector was placed in the distance of over 20cm from the collimator. Therefore we installed the monitor holders near the bismuth block in order to set three gold wire monitors. The factors were determined in the calibration experiments that measure the thermal neutron flux in the phantom and reaction rate of the gold wire monitors. The monitoring technique to measure epithermal neutron beam intensity was applied to clinical irradiation with the epithermal neutron beam.

Journal Articles

Reproducibility of thermal neutron flux distribution on patient's brain surface with a realistic phantom

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Yamamoto, Tetsuya*; Matsumura, Akira*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(2), p.193 - 199, 2004/06

To investigate the possibility of experimental approach for dose evaluation using a realistic phantom that faithfully reproduced the shape of a head, this research considered the manufacture of a patient's realistic phantom and the reappearance of actual medical irradiation conditions. We selected the rapid prototyping technology to produce the realistic phantom from the Computed Tomography (CT) imaging. This phantom was irradiated under the same clinical irradiation condition of this patient, and the thermal neutron distribution on the brain surface was measured in detail. Several subjects on material and data conversion in the production of realistic phantom were mentioned. As a result of reproducing medical irradiation using the realistic phantom, the maximum thermal neutron flux became a value about 22% lower than the surface of the actual brain. If the problems pointed out in this paper are solved, it may also be expected that it would become possible to check computational dosimetry system.

Journal Articles

Evaluation of counting efficiency of whole-body counter using voxel phantoms

Kinase, Sakae; Takagi, Shunji*; Noguchi, Hiroshi; Saito, Kimiaki

Proceedings of 11th International Congress of the International Radiation Protection Association (IRPA-11) (CD-ROM), 7 Pages, 2004/05

The present study was performed to validate the UCWBC code for calibrating in vivo measurements. Furthermore, the calibration data for the adult voxel phantoms developed in JAERI were evaluated by the UCWBC code in order to examine the differences between the calibration data for voxel phantoms, including a voxel version of water-filled block-shape phantom based on an actual phantom that is used for the calibration of the whole-body counter in JAERI. It was found that the calculated calibration data by the UCWBC code for the water-filled block-shape phantom show good agreement with measured ones. Consequently, the UCWBC code was validated by the comparisons. It was also found that the calibration data depend on phantoms of different sizes and the effective distance between phantom and detector. The calibration of in vivo measurements using voxel phantoms for individuals would be quite useful for the improvement in accuracy of the measurement results.

Journal Articles

Energy dependence of absorbed dose distributions in a soft tissue substitute for neutron dosimetry

Tsuda, Shuichi; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 41(Suppl.4), p.132 - 135, 2004/03

A solid material improved in hydrogen and oxygen contents was synthesized for development of a physical phantom for neutron. The elemental composition and density are aimed for those of the soft tissue in ICRU Report 44. The soft tissue equivalence has been verified by an absorbed dose measurement using a 252Cf neutron source. In the present work, absorbed doses were measured for the purpose of examinations of the characteristic of the synthesized soft tissue substitute for neutron of various energies, using mono-energetic 0.565 MeV neutrons from $$^{7}$$Li(p,n) reaction and 5 MeV from D(d,n) reaction, and quasi-mono-energetic ones (40 and 65 MeV) produced via $$^{7}$$Li(p,n) reaction. The measured absorbed doses were compared with those calculated by Monte Carlo simulation codes. The results indicate that the tissue substitute has a characteristic of soft tissue equivalence for neutron in the energy range from several hundred keV up to approximately 100 MeV.

Journal Articles

Evaluation of S values for beta-ray emitters in voxel phantoms

Kinase, Sakae; Zankl, M.*; Funabiki, Jun*; Noguchi, Hiroshi; Saito, Kimiaki

KEK Proceedings 2003-15, p.45 - 52, 2004/02

no abstracts in English

Journal Articles

Synthesis and characterization of a soft-tissue substitute for neutron dosimetry

Tsuda, Shuichi; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 40(12), p.1027 - 1031, 2003/12

 Times Cited Count:1 Percentile:11.2(Nuclear Science & Technology)

To develop a physical phantom for neutron dosimetry, a solid soft-tissue substitute was synthesized. The hydrogen and oxygen compositions of the synthesized tissue substitute, NAN-JAERI, are similar to those of the soft tissue in ICRU Report 44. To examine the radiation characteristics of the new soft-tissue substitute, absorbed dose distributions in NAN-JAERI were measured using a $$^{252}$$Cf neutron source. The measured absorbed dose distributions of neutrons and photons agree with those calculated by a Monte Carlo simulation code MCNP. The agreement between the experiment and the simulation verifies this method of evaluating the soft-tissue equivalence of NAN-JAERI for $$^{252}$$Cf neutrons. Similar simulations for some mono-energetic neutron sources showed that the newly developed tissue substitute has soft-tissue equivalent characteristics in the neutron energy range up to 14 MeV, in terms of the absorbed dose distributions in a slab phantom.

Journal Articles

Evaluation of specific absorption fractions in voxel phantoms using Monte Carlo simulation

Kinase, Sakae; Zankl, M.*; Kuwabara, Jun; Sato, Kaoru; Noguchi, Hiroshi; Funabiki, Jun*; Saito, Kimiaki

Radiation Protection Dosimetry, 105(1-4), p.557 - 563, 2003/09

 Times Cited Count:26 Percentile:84.61(Environmental Sciences)

There exists a need to calculate specific absorbed fractions (SAFs) in voxel phantoms for internal dosimetry. For this purpose, an EGS4 user code for calculating SAFs using voxel phantoms was developed on the basis of an existing EGS4 user code for external dosimetry (UCPIXEL). In the developed code, the transport of photons, electrons and positrons in voxel phantoms can be simulated, particularly the transport simulations of secondary electrons in voxel phantoms can be made. The evaluated SAFs for the GSF Child voxel phantom using the developed code were found to be in good agreement with the GSF evaluated data. In addition, SAFs in adult voxel phantoms developed at JAERI were evaluated using the developed code and were compared with several published data. It was found that SAFs for organ self-absorption depend on the organ masses and would be affected by differences in the structure of the human body.

JAEA Reports

Study on advancement of ${it in vivo}$ counting using mathematical simulation

Kinase, Sakae

JAERI-Research 2003-011, 104 Pages, 2003/05

JAERI-Research-2003-011.pdf:5.11MB

In the present study, a calibration technique for in vivo counting application using Monte Carlo simulation was developed. The advantage of the technique is that counting efficiency can be obtained for various shapes, sizes that is very difficult to change for phantoms. The method for the determination of counting efficiency curves as a function of energy was developed using the present technique and a physiques correction equation was derived from the relationship between parameters of correction factor and counting efficiencies of the JAERI whole-body counter. The uncertainties in body burdens of Cs-137 estimated with the JAERI whole-body counter were also investigated using the Monte Carlo simulation and measurements. Furthermore, the evaluation method of the peak efficiencies of a Ge semi-conductor detector was developed by the Monte Carlo simulation for optimum arrangement of Ge semi-conductor detectors for designing a precision whole-body counter.

Journal Articles

Study on advancement of ${it in vivo}$ counting using mathematical simulation, in Japanese

Kinase, Sakae

Medical Physics, 30(5), P. 994, 2003/05

A calibration technique for in vivo counting application using Monte Carlo simulation was developed. To validate the calibration technique by calculations, the response functions and counting efficiencies of a whole-body counter installed in JAERI were evaluated using the simulation and measurements. Consequently, the calculations are in good agreement with the measurements. The uncertainties in body burdens of 137Cs estimated with the whole-body counter were also investigated using the Monte Carlo simulation and measurements. It was found that the uncertainties of body burdens estimated with the whole-body counter are strongly dependent on various sources of uncertainty such as radioactivity distribution within the body and counting statistics.

Journal Articles

Effect of phantom material on backscattered radiation against photon irradiation

Takahashi, Fumiaki; Yamaguchi, Yasuhiro

Radioisotopes, 52(2), p.94 - 97, 2003/02

Effect of phantom material on backscattered radiations was studied for photon irradiation. Monte Carlo calculations using MCNP-4B code were performed to analyze scattered radiation on the surface of 30x30x15cm3 slab phantoms with different material. Dose on the surface of a human body was also estimated with a modified MIRD-5 type phantom. No significant difference of dose due to scattered radiation was observed between a soft tissue slab and phantom the water-filled slab phantom recommended by the International Organization for Standardization. On the other hand, dose on the surface of the PMMA phantom was found to be larger than doses on the phantom with water or soft tissue. The results also showed that response of dosimeter on the ISO phantom would be near to that on the trunk of a human body.

Journal Articles

Analyses of absorbed dose to tooth enamel against external photon exposure

Takahashi, Fumiaki; Yamaguchi, Yasuhiro; Iwasaki, Midori*; Miyazawa, Chuzo*; Hamada, Tatsuji*; Funabiki, Jun*; Saito, Kimiaki

Radiation Protection Dosimetry, 103(2), p.125 - 130, 2003/01

 Times Cited Count:4 Percentile:32.21(Environmental Sciences)

Absorbed dose to tooth enamels against external photon exposure was examined by the Electron Spin Resonance (ESR) dosimetry using tooth samples placed in a realistic physical phantom. Dose to teeth region was also measured with thermo-luminescence dosimeters (TLDs). A voxel-type phantom was constructed from CT images of the physical phantom. Monte Carlo calculations with this voxel-type phantom were performed to analyse the results of the experiments. The obtained data in this study were compared to the enamel doses, which were calculated with a modified MIRD-type and already given in a previous paper. The results suggested that the conversion factors from enamel dose to organ doses obtained by the modified MIRD-type phantom are to be applicable for retrospective individual dose assessments by the ESR dosimetry. The analysis, however, indicated that the size and figure of the head can affect the enamel dose for low photon energy region below 100keV.

Journal Articles

Detailed dose assessment for the heavily exposed workers in the Tokai-mura criticality accident

Endo, Akira; Yamaguchi, Yasuhiro; Takahashi, Fumiaki

Radiation Risk Assessment Workshop Proceedings, p.151 - 156, 2003/00

We have developed a new system using numerical simulation technique for analyzing dose distribution in various postures by neutron, photon and electron exposures. The system consists of mathematical human phantoms with movable arms and legs and Monte Carlo codes MCNP and MCNPX. This system was applied to the analysis of dose distribution for the heavily exposed workers in the Tokai-mura criticality accident. The paper describes the simulation technique employed and a summary of the dose analysis.

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