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.
Ochi, Kotaro; Funaki, Hironori; Yoshimura, Kazuya; Iimoto, Takeshi*; Matsuda, Norihiro; Sanada, Yukihisa
Radiation and Environmental Biophysics, 61(1), p.147 - 159, 2022/03
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.
Petoussi-Henss, N.*; Satoh, Daiki; Schlattl, H.*; Zankl, M.*; Spielman, V.*
Radiation and Environmental Biophysics, 60(1), p.93 - 113, 2021/03
In this study, the nuclide-specific organ dose coefficients of pregnant female and its fetus for environmental external exposures have been evaluated. The radiation sources were uniformly put in the soil at the depth of 0.5 g cm or in the atmosphere. The environmental radiation fields for the soil contamination were analyzed by using the radiation transport code PHITS, and the fields for the air submersion were taken from the existing data analyzed by the YURI code. The numerical models of the pregnant female and its fetus were put in the environmental radiation fields, and the radiation transport simulations were performed using the EGS code to obtain the organ absorbed doses. From the simulation results, it was found that the radionuclide-specific uterus doses of the pregnant female agreed with the total body doses of the fetus within 6%, except for some radionuclides which emit the low-energy photons below 50 keV. Using the organ dose coefficients evaluated in the present study, the doses of the pregnant female and its fetus can be estimated easily from the data of activity concentration of the radionuclides distributed in the environment.
Kobashi, Yusuke*; Kataoka, Takahiro*; Kanzaki, Norie; Ishida, Tsuyoshi*; Sakoda, Akihiro; Tanaka, Hiroshi; Ishimori, Yuu; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
Radiation and Environmental Biophysics, 59(3), p.473 - 482, 2020/08
Radon therapy has been traditionally performed globally for oxidative stress-related diseases. Many researchers have studied the beneficial effects of radon exposure in living organisms. However, the effects of thoron, a radioisotope of radon, have not been fully examined. In this study, we aimed to compare the biological effects of radon and thoron inhalation on mouse organs with a focus on oxidative stress. Male BALB/c mice were randomly divided into 15 groups: sham inhalation, radon inhalation at a dose of 500 Bq/m or 2000 Bq/m, and thoron inhalation at a dose of 500 Bq/m or 2000 Bq/m were carried out. Immediately after inhalation, mouse tissues were excised for biochemical assays. The results showed a significant increase in superoxide dismutase and total glutathione, and a significant decrease in lipid peroxide following thoron inhalation under several conditions. Additionally, similar effects were observed for different doses and inhalation times between radon and thoron. Our results suggest that thoron inhalation also exerts antioxidative effects against oxidative stress in organs. However, the inhalation conditions should be carefully analyzed because of the differences in physical characteristics between radon and thoron.
Kofler, C.*; Domal, S.*; Satoh, Daiki; Dewji, S.*; Eckerman, K.*; Bolch, W. E.*
Radiation and Environmental Biophysics, 58(4), p.477 - 492, 2019/11
In the current radiation protection system, the International Commission on Radiological Protection (ICRP) recommends to use the effective dose for dose estimation. The effective dose is derived from the organ doses calculated using the computational human models (phantoms) defined by the ICRP to represent the reference person at each age. Questions arise, however, among the general public regarding the accuracy of organ and effective dose estimates based upon reference phantom methodologies, especially for those individuals with heights and/or weights that differ from the nearest age-matched reference person. In this paper, the detriment-weighted dose was defined for non-reference persons as the same manner to the effective dose for reference person. The doses were calculated for external exposure to radionuclides in a soil using 351-member phantom library based on the data of the U.S. population reported by the U.S. National Center for Health Statistics. The results for 33 nuclides were listed in the paper. Especially, for the environmental relevant radionuclides of Sr, Sr, Cs, and I, the detriment-weighted dose of 1-year-old phantom agreed with the effective dose within 5%, while the range of percent differences in these two quantities increased with increases the body size and age, e.g. +15% to -40% for adults.
Ishimori, Yuu; Tanaka, Hiroshi; Sakoda, Akihiro; Kataoka, Takahiro*; Yamaoka, Kiyonori*; Mitsunobu, Fumihiro*
Radiation and Environmental Biophysics, 56(2), p.161 - 165, 2017/05
In order to investigate the biokinetics of inhaled radon, radon concentrations in mouse tissues and organs were determined after mice had been exposed to about 1 MBq/m of radon in air. Radon concentrations in mouse blood and in other tissues and organs were measured with a liquid scintillation counter and with a well-type HP Ge detector, respectively. Radon concentration in mouse blood was 0.4100.016 Bq/g when saturated with 1 MBq/m of radon concentration in air. In addition, average partition coefficients obtained were 0.740.19 for liver, 0.460.13 for muscle, 9.090.49 for adipose tissue, and 0.220.04 for other organs. With these results, a value of 0.414 for the blood-to-air partition coefficient was calculated by means of our physiologically based pharmacokinetic model. The time variation of radon concentration in mouse blood during exposure to radon was also calculated. All results are compared in detail with those found in the literature.
Sakoda, Akihiro; Ishimori, Yuu; Yamaoka, Kiyonori*; Kataoka, Takahiro*; Mitsunobu, Fumihiro*
Radiation and Environmental Biophysics, 52(3), p.389 - 395, 2013/08
This paper provides absorbed doses arising from radon gas in air retained in lung airway lumens. Because radongas exposure experiments often use small animals, the calculation was performed for mice and rats. For reference, the corresponding computations were also done for humans. Assuming that radon concentration in airway lumens is the same as that in the environment, its progeny's production in and clearance from airways were simulated. Absorbed dose rates were obtained for three lung regions and the whole lung, considering that secretory and basal cells are sensitive to radiation. The results showed that absorbed dose rates for all lung regions and whole lung increase from mice to rats to humans. For example, the dose rates for the whole lung were 25.4 in mice, 41.7 in rats, and 59.9 pGy/(Bq/m)/h in humans. Furthermore, these values were also compared with lung dose rates from two other types of exposures, i.e., due to inhalation of radon or its progeny, which were already reported. It was confirmed that the direct inhalation of radon progeny in the natural environment, which is known as a cause of lung cancer, results in the highest dose rates for all species. Based on the present calculations, absorbed dose rates of the whole lung from radon gas were lower by a factor of about 550 (mice), 200 (rats) or 70 (humans) than those from radon progeny inhalation. The calculated dose rate values are comparatively small. Nevertheless, the present study is considered to contribute to our understanding of doses from inhalation of radon and its progeny.
Shiina, Takuya; Watanabe, Ritsuko; Shiraishi, Iyo; Suzuki, Masao*; Sugaya, Yuki; Fujii, Kentaro; Yokoya, Akinari
Radiation and Environmental Biophysics, 52(1), p.99 - 112, 2013/03
Sakoda, Akihiro; Ishimori, Yuu; Fukao, Kosuke*; Yamaoka, Kiyonori*; Kataoka, Takahiro*; Mitsunobu, Fumihiro*
Radiation and Environmental Biophysics, 51(4), p.425 - 442, 2012/11
Biological response of exposure to radon progeny has long been investigated, but there are few studies in which absorbed doses in lungs were estimated if laboratory animals were used. The present study is the first attempt to calculate the doses of inhaled radon progeny for mice. For reference, the doses for rats and humans were also computed with the corresponding models. Lung deposition of particles, their clearance, and energy deposition of alpha particles to sensitive tissues were systematically simulated. Absorbed doses to trachea and bronchi (BB), bronchioles and terminal bronchioles (bb), alveolar-interstitial (AI) regions, and whole lung were first provided as a function of monodisperse radon-progeny particles with an equilibrium equivalent radon concentration of 1 Bq m-3 (equilibrium factor: 0.4 and unattached fraction: 0.01). Based on the results, absorbed doses were then calculated for (1) a reference mine condition and (2) a condition previously used for animal experiments. It was found that the whole lung doses for mice, rats and humans were 34.8, 20.7 and 10.7 nGy (Bq m) h for the mine condition, respectively, while they were 16.9, 9.9 and 6.5 nGy (Bq m) h for the animal experimental condition. In both cases, the values of mice are about 2 times higher than those of rats, and about 3 times higher than those of humans. Comparison of our data on rats and humans with those published in the literature shows an acceptable agreement, suggesting the validity of the present modeling for mice. In the future, a more sophisticated dosimetric study of inhaled radon progeny in mice would be desirable to demonstrate how anatomical, physiological and environmental parameters can influence absorbed doses.
Saito, Kimiaki; Ishigure, Nobuhito*; Petoussi-Henss, N.*; Schlattl, H.*
Radiation and Environmental Biophysics, 51(4), p.411 - 423, 2012/11
Sato, Tatsuhiko; Endo, Akira; Sihver, L.*; Niita, Koji*
Radiation and Environmental Biophysics, 50(1), p.115 - 123, 2011/03
Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients and cosmic-ray fluxes around spacecrafts. The accuracies of the obtained absorbed-dose and dose-equivalent rates were clearly verified by various experimental data measured both inside and outside spacecrafts. The calculation quantitatively shows that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors.
Sihver, L.*; Sato, Tatsuhiko; Puchalska, M.*; Reitz, G.*
Radiation and Environmental Biophysics, 49(3), p.351 - 357, 2010/08
In this paper we will present simulations using the three-dimensional Monte Carlo Particle and Heavy Ion Transport code System (PHITS) of long term dose measurements performed with the European Space Agency (ESA) supported experiment MATROSHKA (MTR), which is an anthropomorphic phantom containing over 6000 radiation detectors, mimicking a human head and torso.
Chen, J.*; Timmins, R.*; Verdecchia, K.*; Sato, Tatsuhiko
Radiation and Environmental Biophysics, 48(3), p.317 - 322, 2009/04
The worldwide average exposure to cosmic rays contributes to about 16% of the annual effective dose from natural radiation sources. At ground level, doses from cosmic ray exposure depend strongly on the elevation above sea level, and weakly on geographical locations and solar activities. With the analytical model PARMA developed by the Japan Atomic Energy Agency, annual effective doses due to cosmic ray exposure at ground level were calculated for more than 1500 communities across Canada which cover more than 85% of the Canadian population. Averaged over solar activities, the Canadian population weighted average annual effective dose due to cosmic ray exposure at ground level is estimated to be 0.31 mSv.
Endo, Satoru*; Tomita, Jumpei*; Tanaka, Kenichi*; Yamamoto, Masayoshi*; Fukutani, Satoshi*; Imanaka, Tetsuji*; Sakaguchi, Aya*; Amano, Hikaru; Kawamura, Hidehisa*; Kawamura, Hisao*; et al.
Radiation and Environmental Biophysics, 47(3), p.359 - 365, 2008/07
Dolon village located about 60 km from the border of the Semipalatinsk Nuclear Test Site is known to be heavily contaminated by the first USSR atomic bomb test in August 1949. Soil samples around Dolon were taken in October 2005 in an attempt to evaluate internal thyroid dose arising from incorporation of radioiodine isotopes (mainly I). Iodine-129 in soil was measured by using the technique of Accelerator Mass Spectrometry. From the relationship between I and Cs (corrected for background and decay from 1949 to 2005) accumulated levels, the background level of I and the I/Cs ratio around Dolon were estimated to be (6.4 0.4) 10 atoms m and 0.25 0.16, respectively. This I/Cs ratio is almost similar to the fission yield ratio for Pu fast fission (0.24).
Watanabe, Ritsuko; Saito, Kimiaki
Radiation and Environmental Biophysics, 41(3), p.207 - 215, 2002/08
no abstracts in English
Tu, Z.; Kobayashi, Yasuhiko; Kiguchi, Kenji*; Watanabe, Hiroshi
Radiation and Environmental Biophysics, 41(3), p.231 - 234, 2002/08
no abstracts in English
Shikazono, Naoya; Tanaka, Atsushi; Kitayama, Shigeru*; Watanabe, Hiroshi; Tano, Shigemitsu*
Radiation and Environmental Biophysics, 41(2), p.159 - 162, 2002/04
no abstracts in English
Shimono, Kazuhiko*; Shikazono, Naoya; Inoue, Masayoshi*; Tanaka, Atsushi; Watanabe, Hiroshi
Radiation and Environmental Biophysics, 40(3), p.221 - 225, 2001/09
no abstracts in English
Saito, Kimiaki; Wittmann, A.*; Koga, Sukehiko*; Ida, Yoshihiro*; Kamei, Tetsuya*; Funabiki, Jun*; Zankl, M.*
Radiation and Environmental Biophysics, 40(1), p.69 - 76, 2001/04
no abstracts in English