Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yamashita, Takuma*; Iwami, Satone*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2024-6, p.85 - 90, 2024/12
To clarify the radiation effects of the accident at the TEPCO's Fukushima Daiichi NPP on living organisms, it is important to accurately estimate the dose to each individual. We have developed a multi-component analysis program using random number optimization to extract only the components derived from carbonate radicals from the ESR spectra.
Iwami, Satone*; Yamashita, Takuma*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2024-6, p.91 - 95, 2024/12
We aim to improve the detection limit of the ESR dosimetry method. In this study, the saturation behavior of each radical was investigated by varying the microwave power during ESR measurement. Based on the difference in spin relaxation time between carbonate radicals and native radicals, it is expected that the signal-to-noise ratio improves and the detection limit can be lowered when the microwave power is increased to 4.0 mW.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.
Radiation Protection Dosimetry, 199(14), p.1620 - 1625, 2023/09
Times Cited Count：1 Percentile：25.62(Environmental Sciences)We have been conducting dose assessments for Japanese macaques captured in Fukushima to reveal radiobiological effects on the low-dose expose animals. To accurately determine the external exposure dose, it is desirable to examine the analysis of the CO
radical intensity. We examined ESR spectra of teeth of 10 macaques captured in Fukushima by two spectrum-decomposition algorithms.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.
KEK Proceedings 2022-2, p.120 - 125, 2022/11
We investigate the effect of sample's anisotropy and measurement condition to obtain the higher reproducibility for the shape of the ESR spectrum and the intensity of CO radical.
Ishikawa, Ryoya*; Suzuki, Masatoshi*; Kino, Yasushi*; Endo, Satoru*; Nakajima, Hiroo*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Shinoda, Hisashi*; et al.
KEK Proceedings 2022-2, p.61 - 66, 2022/11
The balance between oxidative stress and antioxidant activity, which is a defense mechanism against oxidative stress, was investigated in the liver and bladder of wild Japanese macaques captured in Fukushima Prefecture. No significant induction of oxidative stress by exposure to environmental radionuclides after the Fukushima nuclear accident was observed, suggesting that the stress defense mechanism of the organism is activated in some organs.
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; Sasaki, Keiichi*; et al.
Journal of Radiation Research (Internet), 63(4), p.609 - 614, 2022/07
Times Cited Count：3 Percentile：35.92(Biology)Electron spin resonance (ESR) dosimetry is one of the most powerful tools for radiation dose reconstruction. The detection limit of this technique using human teeth is reported to be 56 mGy or 67 mGy; however, the absorbed dose of Fukushima residents after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident was estimated to be lower than this detection limit. Our aim is to assess the absorbed radiation dose of children in Fukushima Prefecture after the accident; therefore, it is important to estimate the detection limit for their teeth. The detection limit for enamel of deciduous teeth of Japanese children separated by the mechanical method is estimated to be 115.0 mGy. The density separation method can effectively separate enamel from third molars of Japanese people. As we have collected thousands of teeth from children in Fukushima, the present technique may be useful to examine their external absorbed dose after the FNPP accident.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2021-2, p.91 - 96, 2021/12
We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.
Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometryKoarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.
Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08
Times Cited Count：7 Percentile：53.68(Chemistry, Analytical)Rapid analysis of Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of Sr in small bone and tooth samples derived from terrestrial animals.
Takahashi, Atsushi*; Chiba, Mirei*; Tanahara, Akira*; Aida, Jun*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Murakami, Shinobu*; Koarai, Kazuma; Ono, Takumi*; Oka, Toshitaka; et al.
Scientific Reports (Internet), 11(1), p.10355_1 - 10355_11, 2021/05
Times Cited Count：9 Percentile：40.51(Multidisciplinary Sciences)
)Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.
Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03
Times Cited Count：13 Percentile：83.05(Agriculture, Dairy & Animal Science)We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Mitsuyasu, Yusuke*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; et al.
Radiation Measurements, 134, p.106315_1 - 106315_4, 2020/06
Times Cited Count：9 Percentile：65.08(Nuclear Science & Technology)The relationship between the CO
radical intensity and the absorbed dose (dose response curve) of tooth enamel of Japanese macaque was observed by electron spin resonance and the detection limit of our system was estimated to be 33.5 mGy, which is comparable to the detection limit for human molar teeth. Using the dose response curve, external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined. The results suggest that the external exposure dose for the wild Japanese macaques were ranged between 45 mGy to 300 mGy.
Ishikawa, Ryoya*; Suzuki, Masatoshi*; Kino, Yasushi*; Endo, Satoru*; Nakajima, Hiroo*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Shinoda, Hisashi*; et al.
no journal, ,
In order to investigate the influence on the oxidative stress status by the long-term exposure after the Fukushima Daiichi Nuclear power plant (FNPP) accident, we analyzed oxidative stress markers in liver and bladder of wild Japanese macaques in the ex-evacuation zone. In liver, the concentration of malondialdehyde (MDA) in approximately 70% of the exposed group exceeded the average and SOD activity of the exposed group shifted toward lower within the range indicated in the control group. By contrast, alteration of MDA concentration and SOD activity in bladder was opposite to that shown in liver. We also found that oxidative stress markers changed in the same manner by external and internal exposure. Our data suggested that exposure to low dose/low dose-rate radiation following the FNPP accident may affect the sensitivity to oxidative stress by changing the activity of antioxidant enzymes.
Oka, Toshitaka; Takahashi, Atsushi*; Miura, Tomisato*; Shinoda, Hisashi*
no journal, ,
From the point of view of dosimeter, tooth enamel has a great sensitivity to radiation and it can be a powerful probe to detect dose from the order of mGy to Gy. In this work, we evaluated the performance of tooth enamel as a high sensitive solid-state dosimeter. Absorbed dose estimated by ESR dosimetry technique was consistent with dose measured by a commerical pocket dosimeter within an error bar, It suggests that tooth enamel can be use as a "non-directional characteristics" dosimeter, which detect dose in mGy order as well as a commercial pocket dosimeter.
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Ono, Takumi*; Tamaki, Hiroaki*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.
no journal, ,
Releases of the radioactive materials from the Fukushima Daiichi Nuclear Power Plant accident result in an ionization exposure to people and animals, the precise dosimetry is required. To estimate the external dose due to the accident, we utilize electron spin resonance (ESR) spectroscopy which is a powerful tool for the dosimetry of external dose. The detection limit of this technique was 146 mGy, so that we have to improve the detection limit for the precise dosimetry. In this work, we developed a novel enamel-dentine separation technique and improved the detection limit down to 43 mGy, and estimated the external dose for Japanese macaque and Procyon lotor collected in Fukushima prefecture.
Oka, Toshitaka; Mitsuyasu, Yusuke*; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Okutsu, Kenichi*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
Releases of the radioactive materials from the Fukushima Daiichi Nuclear Power Plant accident result in a low dose exposure to wild animals. The external dose of wild animals is commonly estimated by the external dose rate of the captured point, but the estimated exposure dose has huge uncertainties because the size of the habitat and/or the movement of the wild animals are not included in the estimation. To estimate the external dose precisely, we utilize electron spin resonance (ESR) dosimetry. In this work, we investigated the sample preparation procedure of wild animals. The ESR spectrum of enamel of racoon captured in Namie-town, Fukushima has a broad ESR signal due to metal components. The linear relationship between the Co intensity and the absorbed dose that we can apply ESR dosimetry for racoon teeth. Using this relationship, the external exposure dose was estimated.
Oka, Toshitaka; Takahashi, Atsushi*; Mitsuyasu, Yusuke*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Yamashita, Takuma*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
Electron spin resonance (ESR) dosimetry technique is a powerful tool that has been used in the study of external exposure dose assessment of human by measuring CO radicals of teeth. In this work, we applied this technique for wild monkey and wild racoon captured in Fukushima prefecture, and estimated the external exposure dose.
Yamashita, Takuma*; Mitsuyasu, Yusuke*; Ono, Kenta*; Iwami, Satone*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
In order to clarify the radiation effects of the Fukushima Daiichi Nuclear Power Plant accident on living organisms, it is important to estimate the radiation dose to individual organisms. We have focused on carbonate radicals that induced in tooth enamel due to radiation, and have estimated the dose by using electron spin resonance technique. In this presentation, we report the results of dose response of radiation-induced radicals and the application of this method to low-dose area by using tooth enamel of Japanese macaque and hydroxyapatite.
Takahashi, Atsushi*; Chiba, Mirei*; Suzuki, Toshihiko*; Kino, Yasushi*; Koarai, Kazuma; Oka, Toshitaka; Nakamura, Fumihiko*; Igarashi, Minoru*; Umino, Makoto*; Osaka, Ken*; et al.
no journal, ,
We have collected more than 7,000 deciduous teeth that spontaneously drop out in the process of being replaced by permanent teeth for more than 10 years after the Fukushima Daiichi Nuclear Power Plant accident from all over Japan, mainly from Fukushima Prefecture, and have investigated whether the amount of radioactive materials in dentition formed after the nuclear accident is increased compared to teeth formed before the accident, using Imaging plates have been used to investigate whether the amount of radioactive materials in the dentition formed after the nuclear accident increased compared to teeth formed before the accident. Comparison of teeth formed before and after the accident suggested that even if radionuclides were taken into the body after the accident, they did not significantly increase the amount of radionuclides in the teeth.
Yamashita, Takuma*; Mitsuyasu, Yusuke*; Ono, Kenta*; Iwami, Satone*; Hayashi, Teppei*; Kino, Yasushi*; Sekine, Tsutomu*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; et al.
no journal, ,
no abstracts in English
Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Fujiwara, Kenso; Terashima, Motoki; Kino, Yasushi*; Oka, Toshitaka; Okutsu, Kenichi*; Yamashita, Takuma*; et al.
no journal, ,
We demonstrated a method of Sr measurement in small pieces of hard tissues with radioactivity measurement or ICP-MS measurement. Interference elements of the measurements were removed by chemical separation. We could determine Sr in 0.1 g of hard tissues by radioactivity measurement method and ICP-MS method. Limit of detection of the ICP-MS method was lower than that of the radioactivity measurement. The ICP-MS method is adequate method for distribution analysis of Sr in the hard tissues.
