Validation study of ambient dose equivalent conversion coefficients for radiocaesium distributed in the ground; Lessons from the Fukushima Daiichi Nuclear Power Station accident

Ochi, Kotaro; Funaki, Hironori; Yoshimura, Kazuya; Iimoto, Takeshi*; Matsuda, Norihiro; Sanada, Yukihisa

Radiation and Environmental Biophysics, 61(1), p.147 - 159, 2022/03

https://doi.org/10.1007/s00411-022-00969-3

Organ doses of the fetus from external environmental exposures

Petoussi-Henss, N.*; Satoh, Daiki; Schlattl, H.*; Zankl, M.*; Spielman, V.*

Radiation and Environmental Biophysics, 60(1), p.93 - 113, 2021/03

https://doi.org/10.1007/s00411-020-00891-6

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.

Organ and detriment-weighted dose rate coefficients for exposure to radionuclide-contaminated soil considering body morphometries that differ from reference conditions; Adults and children

Kofler, C.*; Domal, S.*; Satoh, Daiki; Dewji, S.*; Eckerman, K.*; Bolch, W. E.*

Radiation and Environmental Biophysics, 58(4), p.477 - 492, 2019/11

https://doi.org/10.1007/s00411-019-00812-2

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.

Absorbed doses of lungs from radon retained in airway lumens of mice and rats

Sakoda, Akihiro; Ishimori, Yuu; Yamaoka, Kiyonori*; Kataoka, Takahiro*; Mitsunobu, Fumihiro*

Radiation and Environmental Biophysics, 52(3), p.389 - 395, 2013/08

https://doi.org/10.1007/s00411-013-0478-5

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.

Lung dosimetry of inhaled radon progeny in mice

Sakoda, Akihiro; Ishimori, Yuu; Fukao, Kosuke*; Yamaoka, Kiyonori*; Kataoka, Takahiro*; Mitsunobu, Fumihiro*

Radiation and Environmental Biophysics, 51(4), p.425 - 442, 2012/11

https://doi.org/10.1007/s00411-012-0431-z

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.

Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU adult reference computational phantoms

Sato, Tatsuhiko; Endo, Akira; Sihver, L.*; Niita, Koji*

Radiation and Environmental Biophysics, 50(1), p.115 - 123, 2011/03

https://doi.org/10.1007/s00411-010-0330-0

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.

An Estimation of Canadian population exposure to cosmic rays

Chen, J.*; Timmins, R.*; Verdecchia, K.*; Sato, Tatsuhiko

Radiation and Environmental Biophysics, 48(3), p.317 - 322, 2009/04

https://doi.org/10.1007/s00411-009-0226-z

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.

Monte Carlo simulation of strand-break induction on plasmid DNA in aqueous solution by monoenergetic electrons

Watanabe, Ritsuko; Saito, Kimiaki

Radiation and Environmental Biophysics, 41(3), p.207 - 215, 2002/08

https://doi.org/10.1007/s00411-002-0161-8

no abstracts in English

LET dependence of lethality in irradiated by heavy ions

Shikazono, Naoya; Tanaka, Atsushi; Kitayama, Shigeru*; Watanabe, Hiroshi; Tano, Shigemitsu*

Radiation and Environmental Biophysics, 41(2), p.159 - 162, 2002/04

https://doi.org/10.1007/s00411-002-0157-4

no abstracts in English

Construction of a computed tomographic phantom for a Japanese male adult and dose calculation system

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

https://doi.org/10.1007/s004110000082

no abstracts in English