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Yokozuka, Eri*; Seito, Hajime*; Oka, Toshitaka; Kumagai, Yuta; Nagasawa, Naotsugu*
Isotope News, (801), p.46 - 48, 2025/10
no abstracts in English
Seito, Hajime*; Yokozuka, Eri*; Oka, Toshitaka; Kitatsuji, Yoshihiro; Nagasawa, Naotsugu*
Radiation Protection Dosimetry, 200(16-18), p.1656 - 1659, 2024/11
Times Cited Count：0 Percentile：0.00(Environmental Sciences)We have examined dosimetric characteristics of bio-inspired carbonated hydroxyapatite (CO
HAp), which is a main component of calcified tissues like tooth enamel. COHAp powder samples were exposed to gamma-ray with radiation doses ranging from 1 Gy to 1000 Gy at room temperature, and ESR spectra were measured immediately after irradiation and subsequently measured each 1 day during 90 days. The post-irradiation fading resulted in significant 20% decay of the signal amplitude, which stabilised within 7 days after irradiation, and the intensity approached a constant. The sample has good linear dose response in the experiment range of 10 Gy - 1000 Gy. Our results indicate that the COHAp materials is suitable for chemical dosimetry.
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kitatsuji, Yoshihiro
Radiation Protection Dosimetry, 200(16-18), p.1660 - 1665, 2024/11
Times Cited Count：0 Percentile：0.00(Environmental Sciences)In this work, we evaluated the applicability of hydroxyapatite, which is a main component of tooth enamel, as individual dosimeters that can detect from less than 1 Gy to several tens Gy. Commercially available hydroxyapatite was irradiated by 
Co gamma-ray up to 75 Gy and ESR spectrum of the irradiated sample was observed. The relationship between the intensity of produced carbonated radical and the absorbed dose shows a good linearity (
) from 0 to 75 Gy. The detection limit of this samples was estimated to be 99.7 mGy, and the radical intensity do not change for eight month from the irradiation. These results suggest that this sample can be used as a candidate of the individual dosimeter.
Kitamura, Yoshimasa; Oka, Toshitaka; Yokozuka, Eri*; Nagasawa, Naotsugu*; Seito, Hajime*; Kitatsuji, Yoshihiro
no journal, ,
We evaluated the applicability of hydroxyapatite, which is a main component of tooth enamel, as individual dosimeters that can detect from less than 1 Gy. The relationship between the radical intensity and the absorbed dose shows a good linearity from unirradiated (0 Gy) to 75 Gy, and the lower detection limit of this samples was estimated to be ~100 mGy. It suggests that this sample can be used as a candidate of a new soli-state individual dosimeter.
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kumagai, Yuta; Watanabe, Masayuki
no journal, ,
no abstracts in English
Oka, Toshitaka; Yokozuka, Eri*; Seito, Hajime*; Nagasawa, Naotsugu*; Kitatsuji, Yoshihiro
no journal, ,
Alanine dosimeters and Flick dosimeters are known as simple individual dosimeters, but both can only evaluate more than 1 Gy and 40 Gy, respectively, so that they cannot measure low dose in mGy order. In this work, we evaluated the applicability of hydroxyapatite, which is a main component of tooth enamel, as individual dosimeters that can detect from less than 1 Gy to several tens Gy. Commercially available hydroxyapatite (HAP-200) was irradiated by Co-60 gamma-ray and peak height of the ESR radical was plotted against the absorbed dose to obtain the dose response curve. The dose response curve shows a linear relationship from 0 to 10 Gy with the coefficient of determination of R
=1, indicating that hydroxyapatite can be used as an individual dosimeter instead of tooth enamel.
Yokozuka, Eri*; Seito, Hajime*; Nagasawa, Naotsugu*; Oka, Toshitaka; Kumagai, Yuta
no journal, ,
no abstracts in English
Yokozuka, Eri*; Seito, Hajime*; Oka, Toshitaka; Kumagai, Yuta; Nagasawa, Naotsugu*
no journal, ,
no abstracts in English
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kitatsuji, Yoshihiro
no journal, ,
Alanine dosimeter and Fricke dosimeter are widely used as individual dosimeters, but unfortunately they cannot measure less than 1 Gy. We applied ESR dosimetry technique to investigate whether hydroxyapatite, the main component of teeth, is a suitable material for a new dosimeter to detect radiation from mGy to Gy.
Seito, Hajime*; Yokozuka, Eri*; Oka, Toshitaka; Kitatsuji, Yoshihiro; Nagasawa, Naotsugu*
no journal, ,
We have examined dosimetric characteristics of bio-inspired carbonated hydroxyapatite, which is a main component of calcified tissues like tooth enamel. The slope of dose response curve of radical intensity for carbonated hydroxyapatite is equivalent to that for alanine dosimeter and the radical yield is higher than alanine dosimeter, suggesting that carbonated hydroxyapatite can be used for a new dosimeter.
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kumagai, Yuta; Watanabe, Masayuki
no journal, ,
We attempt to fabricate a new disposable solid-state dosimeter capable of detecting the range from mGy to Gy as well as tooth enamel by applying ESR dosimetry technique. In this study, we evaluate the applicability of hydroxyapatite, which is the main component of teeth, to the new dosimeter. The intensity of carbonate radicals was proportional to absorbed dose and the dose-response curve showed a good linear relationship in the range 0-200 Gy, and the detection limit was estimated to be 
100 mGy, slightly higher than that for human teeth.
Seito, Hajime*; Yokozuka, Eri*; Oka, Toshitaka; Yamasaki, Shota*; Kitatsuji, Yoshihiro; Nagasawa, Naotsugu*
no journal, ,
no abstracts in English
Seito, Hajime*; Yokozuka, Eri*; Oka, Toshitaka; Kumagai, Yuta; Nagasawa, Naotsugu*
no journal, ,
no abstracts in English
Seito, Hajime*; Yokozuka, Eri*; Yamasaki, Shota*; Oka, Toshitaka; Kumagai, Yuta; Nagasawa, Naotsugu*
no journal, ,
no abstracts in English
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kitatsuji, Yoshihiro
no journal, ,
We applied ESR dosimetry technique to find a candidate material for a new solid dosimeter, and found out that hydroxyapatite, the main component of teeth, is a suitable material for a new dosimeter to detect radiation from mGy to Gy.
