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Your search keyword '"Tanaka, Kenichi A."' showing total 28 results
Start Over Author "Tanaka, Kenichi A." Journal journal of radiation research
28 results on '"Tanaka, Kenichi A."'

2. Internal organ dose rate conversion coefficients of Japanese macaques to 134Cs,137Cs and 131I.

Author

Takamura, Yuta, Kajimoto, Tsuyoshi, Tanaka, Kenichi, Yamamoto, Tomoya, Suzuki, Masatoshi, Inaba, Yohei, Chida, Koichi, Fukumoto, Manabu, Rangacharyulu, Chary, and Endo, Satoru

Abstract

The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two species. For γ-radiation, there was excellent agreement in the self-absorption rate with the approximate curve of the Japanese macaque, with an average deviation of 2%. The maximum deviation of 12% was for the kidney, which has two organs, so the error with the approximate curve is slightly larger due to the energy loss created between organs. [ABSTRACT FROM AUTHOR]

Published
2023
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4. Internal exposure rate conversion coefficients and absorbed fractions of mouse for 137Cs, 134Cs and 90Sr contamination in body.

Author

Endo, Satoru, Matsutani, Yuki, Kajimoto, Tsuyoshi, Tanaka, Kenichi, and Suzuki, Masatoshi

Subjects
COMPUTED tomography, RADIOTHERAPY
Abstract

The aim of this study was to determine parameters for estimating the internal exposure of all organs in mouse experiments from the radioactivity concentration in organs. The estimation of internal exposure rate conversion coefficients and absorbed fractions for 137Cs, 134Cs and 90Sr by the Particle and Heavy Ion Transport code System (PHITS) with a voxel-based mouse phantom is presented. The geometry of the voxel phantom is constructed from computer tomography images of a mouse 9 cm in length weighing 23.9 g. The voxel-based mouse phantom has the following organs: brain, skull, heart, lungs, liver, stomach, spleen, kidneys, bladder, testis and tissue (tissue and other organs). Gamma- and beta-rays from 137Cs, 134Cs and 90Sr sources in each source organ are generated and scored for every target organ. The internal exposure rate conversion coefficients and absorbed fractions are calculated from deposition energies in each target organ from each source organ and are used to generate an internal exposure rate conversion coefficient matrix and an absorbed fraction matrix. The absorbed fractions of beta-rays in the source organs are roughly 0.5–0.8 for 137Cs and 134Cs, and the absorbed fractions of gamma-rays are <0.04 for 137Cs and <0.03 for 134Cs. The internal exposure rate conversion coefficient matrix is defined using the absorbed fractions. The calculated internal exposure rate coefficient matrix is tested under a uniform radioactivity concentration of 1 Bq/kg for 137Cs, 134Cs and 90Sr. The estimated internal exposure rates in the mouse whole body for 137Cs, 134Cs and 90Sr are 3.28 × 10−3, 2.55 × 10−3 and 1.20 × 10−2 μGy/d, respectively. These values are very similar to those for an ellipsoid frog (31.4 g) and an ellipsoid crab egg mass (12.6 g) reported in ICRP Publication 108. [ABSTRACT FROM AUTHOR]

Published
2020
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6. Anin vitroverification of strength estimation for moving an 125I source during implantation in brachytherapy

Author

Tanaka, Kenichi, primary, Kajimoto, Tsuyoshi, additional, Hayashi, Takahiro, additional, Asanuma, Osamu, additional, Hori, Masakazu, additional, Kamo, Ken-ichi, additional, Sumida, Iori, additional, Takahashi, Yutaka, additional, Tateoka, Kunihiko, additional, Bengua, Gerard, additional, Sakata, Koh-ichi, additional, and Endo, Satoru, additional

Published
2018
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7. Comparison of calculated beta- and gamma-ray doses after the Fukushima accident with data from single-grain luminescence retrospective dosimetry of quartz inclusions in a brick sample

Author

Endo, Satoru, primary, Fujii, Keisuke, additional, Kajimoto, Tsuyoshi, additional, Tanaka, Kenichi, additional, Stepanenko, Valeriy, additional, Kolyzhenkov, Timofey, additional, Petukhov, Aleksey, additional, Akhmedova, Umukusum, additional, and Bogacheva, Viktoriia, additional

Published
2018
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12. An in vitro verification of strength estimation for moving an 125I source during implantation in brachytherapy.

Author

Tanaka, Kenichi, Kajimoto, Tsuyoshi, Hayashi, Takahiro, Asanuma, Osamu, Hori, Masakazu, Kamo, Ken-Ichi, Sumida, Iori, Takahashi, Yutaka, Tateoka, Kunihiko, Bengua, Gerard, Sakata, Koh-Ichi, and Endo, Satoru

Abstract

This study aims to demonstrate the feasibility of a method for estimating the strength of a moving brachytherapy source during implantation in a patient. Experiments were performed under the same conditions as in the actual treatment, except for one point that the source was not implanted into a patient. The brachytherapy source selected for this study was 125I with an air kerma strength of 0.332 U (μGym2h-1), and the detector used was a plastic scintillator with dimensions of 10 cm × 5 cm × 5 cm. A calibration factor to convert the counting rate of the detector to the source strength was measured and then the accuracy of the proposed method was investigated for a manually driven source. The accuracy was found to be under 10% when the shielding effect of additional needles for implantation at other positions was corrected, and about 30% when the shielding was not corrected. Even without shielding correction, the proposed method can detect dead/dropped source, implantation of a source with the wrong strength, and a mistake in the number of the sources implanted. Furthermore, when the correction was applied, the achieved accuracy came close to within 7% required to find the Oncoseed 6711 (125I seed with unintended strength among the commercially supplied values of 0.392, 0.462 and 0.533 U).

Published
2018
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13. Radiation Dose Measurement by Electron Spin Resonance Studies of Tooth Enamel in Lime and Non-lime Consuming Individuals from the Silchar Region of Northeast India

Author

BHATTACHARJEE, Deborshi, primary, IVANNIKOV, Alexander I., additional, ZHUMADILOV, Kassym, additional, STEPANENKO, Valeriy F., additional, TANAKA, Kenichi, additional, ENDO, Satoru, additional, OHTAKI, Megu, additional, TOYODA, Shin, additional, BHATTACHARYYA, Joyeeta, additional, and HOSHI, Masaharu, additional

Published
2009
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18. A Gradient of Radioactive Contamination in Dolon Village Near the SNTS and Comparison of Computed Dose Values with Instrumental Estimates for the 29 August, 1949 Nuclear Test

Author

STEPANENKO, Valeriy F., primary, HOSHI, Masaharu, additional, DUBASOV, Yuriy V., additional, SAKAGUCHI, Aya, additional, YAMAMOTO, Masayoshi, additional, ORLOV, Mark Y., additional, BAILIFF, Ian K., additional, IVANNIKOV, Alexander I., additional, SKVORTSOV, Valeriy G., additional, IASKOVA, Elena K., additional, KRYUKOVA, Irina G., additional, ZHUMADILOV, Kassym S., additional, ENDO, Satoru, additional, TANAKA, Kenichi, additional, APSALIKOV, Kazbek N., additional, and GUSEV, Boris I., additional

Published
2006
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20. Radiation Dose Estimation by Tooth Enamel EPR Dosimetry for Residents of Dolon and Bodene

Author

ZHUMADILOV, Kassym, primary, IVANNIKOV, Alexander, additional, APSALIKOV, Kazbek N., additional, ZHUMADILOV, Zhaxybay, additional, TOYODA, Shin, additional, ZHARLYGANOVA, Dinara, additional, TIELIEWUHAN, Eldana, additional, ENDO, Satoru, additional, TANAKA, Kenichi, additional, MIYAZAWA, Chuzou, additional, OKAMOTO, Tetsuji, additional, and HOSHI, Masaharu, additional

Published
2006
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21. Results of EPR Dosimetry for Population in the Vicinity of the Most Contaminating Radioactive Fallout Trace After the First Nuclear Test in the Semipalatinsk Test Site

Author

IVANNIKOV, Alexander, primary, ZHUMADILOV, Kassym, additional, TIELIEWUHAN, Eldana, additional, JIAO, Ling, additional, ZHARLYGANOVA, Dinara, additional, APSALIKOV, Kazbek N., additional, BEREKENOVA, Gulnara, additional, ZHUMADILOV, Zhaxybay, additional, TOYODA, Shin, additional, MIYAZAWA, Chuzou, additional, SKVORTSOV, Valeriy, additional, STEPANENKO, Valeriy, additional, ENDO, Satoru, additional, TANAKA, Kenichi, additional, and HOSHI, Masaharu, additional

Published
2006
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22. Nuclear Abnormalities in Aspirated Thyroid Cells and Chromosome Aberrations in Lymphocytes of Residents Near the Semipalatinsk Nuclear Test Site

Author

TAKEICHI, Nobuo, primary, HOSHI, Masaharu, additional, IIDA, Shozo, additional, TANAKA, Kimio, additional, HARADA, Yuka, additional, ZHUMADILOV, Zhaxybay, additional, CHAIZHUNUSOVA, Nailya, additional, APSALIKOV, Kazbek N., additional, NOSO, Yoshihiro, additional, INABA, Toshiya, additional, TANAKA, Kenichi, additional, and ENDO, Satoru, additional

Published
2006
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25. Mapping of the cumulative {beta}-ray dose on the ground surface surrounding the Fukushima area

Author

Endo, Satoru, Kajimoto, Tsuyoshi, Tanaka, Kenichi, Nguyen, Thanh T., Hayashi, Gohei, and Imanaka, Tetsuji

Abstract

A large amount of the fission products released by the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on 11 March 2011 was deposited in a wide area from Tohoku to northern Kanto. A map of the estimated cumulative β-ray dose (70 μm dose equivalent) on the soil surface for one year after the FDNPP accident has been prepared using previously reported calculation methods and the 2-km mesh survey data by MEXT. From this map of estimated dose, areas with a high cumulative β-ray dose on the soil surface for one year after the FDNPP accident were found to be located in the Akogi-Teshichiro to Akogi-Kunugidaira region in Namie Town, and in the southern Futaba Town to the northern Tomioka Town region. The highest estimated cumulative β-ray dose was 710 mSv for one year at Akogi-Teshichiro, Namie Town.

Published
2015
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26. Strength estimation of a moving 125Iodine source during implantation in brachytherapy: application to linked sources

Author

Tanaka, Kenichi, Endo, Satoru, Tateoka, Kunihiko, Asanuma, Osamu, Hori, Masakazu, Takagi, Masaru, Bengua, Gerard, Kamo, Ken-ichi, Sato, Kaori, Takeda, Hiromitsu, Hareyama, Masato, Sakata, Koh-ichi, and Takada, Jun

Abstract

This study sought to demonstrate the feasibility of estimating the source strength during implantation in brachytherapy. The requirement for measuring the strengths of the linked sources was investigated. The utilized sources were 125I with air kerma strengths of 8.38–8.63 U (μGy m2 h–1). Measurements were performed with a plastic scintillator (80 mm × 50 mm × 20 mm in thickness). For a source-to-source distance of 10.5 mm and at source speeds of up to 200 mm s–1, a counting time of 10 ms and a detector-to-needle distance of 5 mm were found to be the appropriate measurement conditions. The combined standard uncertainty (CSU) with the coverage factor of 1 (k = 1) was ∼15% when using a grid to decrease the interference by the neighboring sources. Without the grid, the CSU (k = 1) was ∼5%, and an 8% overestimation due to the neighboring sources was found to potentially cause additional uncertainty. In order to improve the accuracy in estimating source strength, it is recommended that the measurment conditions should be optimized by considering the tradeoff between the overestimation due to the neighboring sources and the intensity of the measured value, which influences the random error.

Published
2014
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27. A dosimetry method for low dose rate brachytherapy by EGS5 combined with regression to reflect source strength shortage

Author

Tanaka, Kenichi, Tateoka, Kunihiko, Asanuma, Osamu, Kamo, Ken-ichi, Sato, Kaori, Takeda, Hiromitsu, Takagi, Masaru, Hareyama, Masato, and Takada, Jun

Abstract

The post-implantation dosimetry for brachytherapy using Monte Carlo calculation by EGS5 code combined with the source strength regression was investigated with respect to its validity. In this method, the source strength for the EGS5 calculation was adjusted with the regression, so that the calculation would reproduce the dose monitored with the glass rod dosimeters (GRDs) on a water phantom. The experiments were performed, simulating the case where one of two 125I sources of Oncoseed 6711 was lacking strength by 4–48%. As a result, the calculation without regression was in agreement with the GRD measurement within 26–62%. In this case, the shortage in strength of a source was neglected. By the regression, in order to reflect the strength shortage, the agreement was improved up to 17–24%. This agreement was also comparable with accuracy of the dose calculation for single source geometry reported previously. These results suggest the validity of the dosimetry method proposed in this study.

Published
2014
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28. Estimation of {beta}-ray dose in air and soil from Fukushima Daiichi Power Plant accident

Author

Endo, Satoru, Tanaka, Kenichi, Kajimoto, Tsuyoshi, Thanh, Nguyen Tat, Otaki, Joji M., and Imanaka, Tetsuji

Abstract

Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident of 2011, which deposited radionuclides across Tohoku and northern Kanto, β-ray dose evaluation has been performed to estimate radiation exposure for small creatures like insects as well as human skin. Using the Monte Carlo radiation transport code MCNP-4C, we calculated the β-ray dose for 129mTe, 129Te, 131I, 132Te, 132I, 134Cs and 137Cs in air as a function of altitude and in soil. These calculations of β-dose rate for each radionuclide were conducted for the conditions following the FDNPP accident, with 137Cs deposition assumed to be 1000 kBq/m2. Beta-ray dose rate was found to be ∼10-fold (resp. 5-fold) higher than the γ-ray dose rate in the soil (resp. on the ground surface) at ∼20 days after deposition, and ∼4-fold (resp. 1.7-fold) higher after 6 months or more. For convenience, the height dependence of the ratio for 0, 10, 30, 90, 180 and 365 days after deposition was obtained by a fitting function. The cumulative 70 µm β-ray dose at 30, 60 and 90 days after deposition was estimated to be 35, 45 and 53 mGy for the ground surface, and 61, 79 and 92 mGy in the soil, respectively. These results can be used to estimate the external β-ray exposure for small creatures as well as for human skin.

Published
2014
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