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ray and UVB radiation in ArabidopsisTeranishi, Mika*; Yamaguchi, Hiroko*; Sakamoto, Ayako; Hidema, Jun*
no journal, ,
Shimada, Kazumasa; Kai, Michiaki*
no journal, ,
In this study, we proposed that disability-adjusted life year (DALY) to estimate radiation cancer risk in Japanese residents. DALY is calculated as the sum of Years of Life Lost (YLL) and Years Lived with Disability (YLD). We separately calculated the excess absolute risk for cancer incidence based on the Excess Relative Risk (ERR) and Excess Absolute Risk (EAR) models. Cancer-specific incidence, mortality rates, and the survival fractions exceeding 5 years have been based on data from the National Cancer Center in Japan. The cancer-specific incidence and mortality rate statistics were from 2010 in Japan; the survival fractions exceeding 5 years were from 2003 to 2005 in Japan. We used disability weights (DW) of cancer according to stage diagnosis/therapy in the WHO table. Table illustrates the results of DALY for each cancer site for Japanese after exposure at 1 Gy dose per 1000 persons. Furthermore, the ratio of DALY for each cancer site per DALY for all solid cancers and the ratio of YLL per DALY for each cancer are shown in this Table. We calculated the DALY of radiation solid cancer risk as a measure of health risk. DALY can be a practical tool that can compare many types of diseases encountered in common public health.
Sato, Tatsuhiko; Hamada, Nobuyuki*; Kumada, Hiroaki*
no journal, ,
The planning of heavy ion therapy and BNCT requires radiation dose assessment with consideration of RBE for different radiation quality. We developed a model assembly for estimating the surviving fraction of cells irradiated with various types of ionizing radiation, considering Bcl-2 overexpression and nontargeted effects in the same framework. Using the model assembly in combination with PHITS, the RBE-weighted doses were estimated for several irradiation conditions in carbon-ion therapy and BNCT, the boron concentration and the Bcl-2 overexpression status in each cell being taken into account. The simulation suggested that the consideration of radioresistance due to Bcl-2 overexpression results in the significant increase of the RBE-weighted doses in tumor regions. On the other hand, consideration of nontargeted effects gives trivial impact on the RBE-weighted doses in tumor regions, but slightly increases the values in normal tissue regions.
-irradiation of A-, X-, Y- and mordenite type zeolites in aqueous solutionKumagai, Yuta; Kimura, Atsushi; Taguchi, Mitsumasa
no journal, ,
Zeolite minerals are suitable adsorbents for removal of radioactive cesium in water, because of their high radiation resistances. However, irradiation of zeolites results in decomposition of water adsorbed on the zeolites. Water decomposition produces hydrogen (H
) and hydrogen peroxide (HO). H production has a risk of making an explosive gas mixture. HO causes corrosion of metals and alloys. Therefore, the radiation effects are required to be assessed and controlled. In this study, H and HO production by irradiation of zeolites in aqueous solution are comparatively studied among different types of zeolites, A-, X-, Y- and mordenite-types. The mixtures of the zeolites and aqueous solution were irradiated by 
Co -rays. The A-type and the X-type zeolites produced more H than the Y-type and the mordenite-type. In contrast, the HO production was inhibited by the addition of zeolites. The A-type and the X-type zeolites showed remarkable inhibition. The A-type and the X-type contains more aluminum in their frameworks than the others do. Therefore, the results suggest that aluminum sites have an important role in the reactions induced by irradiation.
Tanaka, Atsushi
no journal, ,
Sato, Tatsuhiko; Nagamatsu, Aiko*; Takeda, Kazuo*; Niita, Koji*; Puchalska, M.*; Sihver, L.*
no journal, ,
Estimation of doses for astronauts due to space radiation exposure has been an essential issue in the planning of long-term space missions. For that purpose, we developed a simulation tool for estimating radiation environments as well as doses for astronauts stayed in the Kibo module in ISS. The tool consists of the Particle and Heavy Ion Transport Simulation code, PHITS, in combination with the virtual Kibo module developed by JAXA. The accuracy of the simulation was examined on the basis of the experimental data obtained from the Area PADLES and MATROSHKA-Kibo measurements. It was found from the examination that the calculated doses agree with the measured data fairly well. The results of the examination also suggested that the consideration of the east-west asymmetry is important to reproduce the location-dependence of doses inside the Kibo module.
Nagamatsu, Aiko*; Sato, Tatsuhiko; Kitajo, Keiichi*; Shimada, Ken*; Sakane, Sayuri*; Takeda, Kazuo*; Niita, Koji*
no journal, ,
Continuous space-radiation dosimetry is one of the key missions at the International Space Station (ISS) for radiation health management of crew members and for scientific activities. Since the Japanese Experiment Module KIBO was attached to the ISS in 2008, we have been performing continuous space radiation dosimetry using a passive and integrating dosimeters, PADLES (Passive Dosimeter for Life-Science Experiments in Space). To date, several hundreds of PALDES having returned from the ISS showed anisotropy of the radiation environment and changes in the dose rate due to ISS attitudes and differences in shielding conditions. On this occasion, an overview of JAXA's continuous radiation dosimetry activities and the preliminary results will be presented with the discussions, which based on the simulation analysis with Particle and Heavy Ion Transport code System PHITS.
Hiroki, Akihiro; Yamashita, Shinichi*; Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa
no journal, ,
The polymer gel dosimeters consisting of 2-hydroxyethyl methacrylate, nonaethylene glycol dimethacrylate, and tetrakis (hydroxymethyl) phosphoniumu chloride with radiation-crosslinked hydroxypropyl cellulose gel were irradiated with 290 MeV/u C ions at HIMAC. Absorbance of the irradiated dosimeters at 660 nm increased with an increase in the dose up to 10 Gy. The dose response of the dosimeter irradiated with C ions was about 0.007 Abs. Gy
, which decreased in about one-tenth of the -irradiated sample. RGB value of the image obtained by using a flat-bed image scanner also increased with increasing dose. Distribution of the dose estimated from RGB value of the scanned image was almost agreement with that of a general radiochromic film for the radiotherapy.
Hirade, Tetsuya
no journal, ,
Ps has a negative work function in insulating materials and the repulsion between Ps and surrounding molecules can form a bubble in liquids. It is needed to lose energy to have a stable bubble state. The Ps bubble stabilizes within about 10 ps in usual liquids, but not in room temperature ionic liquids (IL). It would take about 1 ns in TMPA-TFSI. The ortho-Ps pick off annihilation probability depends on the size of the Ps bubble and hence the change of the ortho-Ps pick-off annihilation rate caused by the change of the bubble size on the lifetime spectra was expected. The results obtained from the lifetime spectra for TMPA-TFSI indicate that the Ps bubble oscillates in IL before the Ps bubble stabilization. On the other hand, the ortho-Ps pick-off annihilation rate obtained at older positron age region showed smaller annihilation rates than the expected one with the surface tension of IL. Positron annihilation methods will be a very strong tool to investigate the structure of IL.
Okawa, Yasuhisa; Seya, Natsumi; Hashimoto, Makoto; Nunokawa, Jun*; Matsuzawa, Hajime*; Yanagawa, Yukihide*; Iimoto, Takeshi*
no journal, ,
Sakoda, Akihiro; Ishimori, Yuu; Tschiersch, J.*
no journal, ,
Some human studies have been made in radon-therapy facilities to measure the intake of radon via skin and the deposition of radon progeny onto skin. In the present study, with based on such empirical data, we addressed dose calculations for various organs and tissues due to these exposures. We have first developed mathematical models expressing the behavior of radon or its progeny in the body, and then optimized the values of parameters required. To compute dose coefficients, the activity of radon or its progeny in skin (and other organs and tissues) during and after the treatment was predicted with the optimized parameters. In the presentation, the results will be presented in detail and compared with other different pathways as inhalation that have ever been reported. The present work would contribute to one's understanding of radon exposure and its resulting doses from various viewpoints.
Ishimori, Yuu; Tanaka, Hiroshi; Sakoda, Akihiro; Kataoka, Takahiro*; Yamaoka, Kiyonori*; Mitsunobu, Fumihiro*
no journal, ,
Various biological responses following radon inhalation are widely known. However, it is few that the responses are discussed quantitatively in relation to absorbed dose due to radon inhaled because experimental data of biokinetics of radon inhaled seem not to be many. To examine biokinetics of radon inhaled, radon concentration in mouse blood was measured after the inhalation of radon with about 1 MBq/
for several to 1000 minutes. Blood was collected from a mouse heart, and radon concentration in blood was determined by a liquid scintillation counter. This was based on the measurement technique used by JAEA for radon in water. The data were corrected taking into account quenching of scintillation. As the result, radon concentration in mouse blood was 0.416
0.014 Bq/g in the condition saturated with 1 MBq/m of radon concentration in the air. The time variation of radon concentration in mouse blood in the condition unsaturated was well expressed by our mathematical model.
Homma, Toshimitsu
no journal, ,
Yamamoto, Hiroyuki; Nojima, Takehiro; Esaka, Fumitaka
no journal, ,
X-ray photoelectron spectroscopy (XPS) is widely used as a non-destructive chemical state analysis method for solid surface. However, depth profiling is often limited due to insufficient analyzing depth. Ion irradiation is often used for depth profiling of XPS, however, chemical state changes are inevitable. Non-destructive analysis is therefore required. In the present study, we examined a method to perform depth profiling with X-ray absorption spectroscopy (XAS) by changing electron energies for detection ranging from 5 to 50 eV using electron spectrometer. Thin Au films (several nm) deposited on Si(100) substrate are used for the specimen. On the basis of the observed results from XAS spectra, significant increase of Si/Au ratio by reducing electron energy. These results indicate non-destructive chemical depth profiling in XAS can be performed by changing electron energies for detection.
Suzuki, Michiyo; Hattori, Yuya; Sakashita, Tetsuya; Funayama, Tomoo; Yokota, Yuichiro; Kobayashi, Yasuhiko
no journal, ,
to microbeam irradiationSakashita, Tetsuya; Suzuki, Michiyo; Hattori, Yuya; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Shirai, Kana*; Kobayashi, Yasuhiko
no journal, ,
We applied the microbeam irradiation of the central nervous tissue in to analyze direct radiation effects at a tissue level. Also, to investigate the mechanism of modulatory effects of irradiation on the salt chemotaxis learnign (SCL), we used two mutants (
and 
) related to the SCL. Well-fed adults of wild-type and mutant were irradiated with 12,000 carbon ion particles corresponding to 500 Gy at micro-aperture area. Immediately after microbeam irradiation, the SCL performance was examined based on the chemotaxis index (CI). CI during the SCL was decreased in the wild-type and mutant animals, but microbeam irradiation did not significantly affect CIs of mutants. The difference of the SCL between and mutants will be discussed at the meeting.
Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Ouchi, Noriyuki; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki
no journal, ,
The production kinetics of abortive colonies was investigated using a model of branching processes. We experimentally determined the colony size distribution of abortive colonies exposed to low linear energy transfer (LET) -rays, and found its linear relationship on the log-log plot. By applying the simple model of branching processes to the linear relationship, we found the persistent reproductive cell death (RCD) over several generations following irradiation. To verify the estimated probability of RCD, the Monte Carlo simulation was used. Radiation-induced RCD lasted over 16 generations and mainly consisted of two components in the early and late phases. Intriguingly, the survival curve was sensitive to the excess probability over 5 generations. Such framework for the combined analysis with a branching process model and a colony formation assay was also applicable to determination of cellular responses to high-LET carbon-ion radiation.
Hattori, Yuya; Yokoya, Akinari; Watanabe, Ritsuko
no journal, ,
When only a limited number of cells in a population are hit by radiation, non-irradiated cells might receive from the irradiated cells intercellular signals that induce biological effects known as "bystander effects". To understand the responses of each cell in the inhomogeneous population, we have developed a mathematical model of intercellular signaling and individual cellular responses, particularly focusing on cell cycle progression, cell cycle arrest, and cell death. In our model, the cellular population was described by grids. Each grid represented each cell. We assumed that absorbed dose was given in each grid (cell). The intercellular-signals emitted from the cells were assumed to be transferred through culture medium and gap junctions, and their concentrations in each grid were calculated based on a diffusion equation. We assumed that individual cell have targets which are necessary to progress the cell cycle. Both irradiation and the intercellular signals were assumed to inactivate "targets" in the cell. The number of inactivated targets decides cellular state, cell cycle progression, cell cycle arrest or cell death. The cell cycle was described as a virtual clock with cyclic stages (G1, S, G2, M phases) and several check-points. In the condition of normal cell-cycle progression and proliferation, our model successfully reproduced growth curves of experimental data previously reported for non-irradiated cellular population. When we irradiated one cell in the center of cellular population, some of non-irradiated cells caused inactivation of the targets by the intercellular signals, resulting in cell cycle arrest and cell death. Based on the simulation and analysis of the temporal and spatial dynamics of intercellular signaling, inactivated targets, cell cycle arrest and cell death, we will discuss the mechanism of radiation-induced responses in inhomogeneous cellular populations.
Seko, Noriaki
no journal, ,