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Journal Articles

Decision making in protection against radiation from nuclear disaster; Risk trade-off and stakeholder involvement

Kanda, Reiko*; Homma, Toshimitsu*; Takahara, Shogo; Tsubokura, Masaharu*; Osako, Masahiro*; Kawaguchi, Isao*; Kato, Takaaki*

Risukugaku Kenkyu, 30(3), p.133 - 139, 2021/04

Almost ten years have passed since Fukushima nuclear accident. Our experience should be used to improve current emergency protective measures and preparedness. A review of the protective measures implemented in the aftermath of Fukushima nuclear accident has revealed problems such as paternalistic intervention for inhabitants and increased health risks due to the evacuation of vulnerable groups. The risk trade-offs in environmental recovery actions are more complex and ongoing; the stakeholders are the next generation and residents outside of the prefecture. Since one of the characteristics of nuclear disasters is the distance and time dependency of the risk, countless individual cases need to be addressed. While generalization of protective measures is essential, the appropriate deployment of personnel in a variety of roles may require to really address individual cases. To improve nuclear emergency preparedness in the future, it is necessary to incorporate both a top-down approach and a bottom-up approach in a well-balanced manner.

Journal Articles

A Branching process model for the analysis of abortive colony size distributions in carbon ion-irradiated normal human fibroblasts

Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki

Journal of Radiation Research, 55(3), p.423 - 431, 2014/02

 Times Cited Count:4 Percentile:26.46(Biology)

Our previous analysis with a branching process model showed that the relative cell death (RCD) in human fibroblasts can persist over 16 generations following irradiation with low linear energy transfer (LET) $$gamma$$-rays. Here we further set out to evaluate the RCD persistency in abortive colonies arising from normal human fibroblasts exposed to high-LET carbon ions (18.3 MeV/u, 108 keV/$$mu$$m). We found that the abortive colony size distribution determined by biological experiments follows the linear relationship on the log-log plot, and that the Monte Carlo simulation using the RCD probability estimated from such linear relationship well simulates the experimentally determined surviving fraction and the relative biological effectiveness (RBE). We identified the short-term phase and long-term phase for the persistent RCD, as was the case for $$gamma$$-irradiation.

Journal Articles

A Framework for analysis of abortive colony size distributions using a model of branching processes in irradiated normal human fibroblasts

Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Ouchi, Noriyuki; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki

PLOS ONE (Internet), 8(7), p.e70291_1 - e70291_10, 2013/07

 Times Cited Count:7 Percentile:39.02(Multidisciplinary Sciences)

Clonogenicity gives important information about the cellular reproductive potential following ionizing irradiation. We firstly plotted the experimentally determined colony size distribution of abortive colonies in irradiated normal human fibroblasts, and found the 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, abortive colony size distribution ($$leq$$15 cells/colony) and the surviving fraction were simulated by the Monte Carlo computational approach. Radiation-induced RCD (i.e. excess probability) lasted over 16 generations and mainly consisted of two components in the early and late phases. We found that short-term RCD is critical to the abortive colony size distribution, and long-lasting RDC is important for the dose response of the surviving fraction.

Oral presentation

Thickness measurements of the stripper foils in the J-PARC 3-GeV RCS

Yoshimoto, Masahiro; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya; Kawaguchi, Kazuhiro*; Sugai, Isao*; Irie, Yoshiro*

no journal, , 

A stripper foil plays an important role for charge-exchange multi-turn injection in high intensity accelerators like the RCS of J-PARC. In order to optimize the foil thickness, the stripping efficiency is obtained by using beam for various thicknesses of the foils. The RCS has three stripper foils. By using a proper combination of three foils, the total H$$^{-}$$ beam, the H$$^{0}$$ and the H$$^{-}$$ beam can be measured separately. As for determining an accurate stripping efficiency, it is very important to know an actual foil thickness. For that purpose, we employed several other methods to measure the foil thickness. The simplest method is the weighing of the foil. Further more accurate methods with the $$alpha$$ particle thickness gauge or the RBS are also adopted. In addition, the cross section of the foil is observed and the thickness is measured directly with the SEM. Through such direct measurements of the foil thickness, an accurate stripping efficiency of the RCS stripper foil can be established.

Oral presentation

A Framework for analysis of abortive colony size distributions using a model of branching processes in irradiated normal human fibroblasts

Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Ouchi, Noriyuki; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki

no journal, , 

Clonogenicity gives important information about the cellular reproductive potential following ionizing irradiation. We firstly plotted the experimentally determined colony size distribution of abortive colonies in irradiated normal human fibroblasts, and found the 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, abortive colony size distribution ($$<$$16 cells/colony) and the surviving fraction were simulated by the Monte Carlo computational approach. Radiation-induced RCD (i.e. excess probability) lasted over 16 generations and mainly consisted of two components in the early and late phases. These results suggest that short-term RCD is critical to the abortive colony size distribution, and long-lasting RDC is important for the dose response of the surviving fraction.

Oral presentation

New insights of the radiation biology from the abortive colony size analysis

Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Ouchi, Noriyuki; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki

no journal, , 

Clonogenicity gives important information about the cellular reproductive potential following ionizing irradiation, but an abortive colony that fails to continue to grow remains poorly characterized. By applying the simple model of branching processes to the linear relationship of the abortive colony size distribution, we found the persistent reproductive cell death (RCD) over several generations following irradiation. Radiation-induced RCD, i.e. excess probability, lasted over 16 generations and mainly consisted of two components in the early ($$<$$3 generations) and late phases. Intriguingly, the survival curve was sensitive to the excess probability over 5 generations, whereas abortive colony size distribution was robust against it. These results suggest that, whereas short-term RCD is critical to the abortive colony size distribution, long-lasting RCD is important for the dose response of the surviving fraction.

Oral presentation

New insights of the radiation biology from the abortive colony size analysis

Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Ouchi, Noriyuki; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki

no journal, , 

Clonogenicity gives important information about the cellular reproductive potential following ionizing irradiation, but an abortive colony that fails to continue to grow remains poorly characterized. 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. In addition, radiation-induced RCD, i.e. excess probability, lasted over 16 generations and mainly consisted of two components in the early (more than 3 generations) and late phases. Intriguingly, the survival curve was sensitive to the excess probability over 5 generations, whereas abortive colony size distribution was robust against it. These results suggest that, whereas short-term RCD is critical to the abortive colony size distribution, long-lasting RCD is important for the dose response of the surviving fraction.

Oral presentation

A Framework for analysis of abortive colony size distributions using a model of branching processes in irradiated normal human fibroblasts

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) $$gamma$$-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.

Oral presentation

A Framework for understanding the production kinetics of abortive colony size distributions in irradiated normal human fibroblasts

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) $$gamma$$-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.

Oral presentation

Current status and issues of low dose and low dose rate radiation risk estimation method; Current status and issues of dose assessment

Sakai, Kazuo*; Yamada, Yu*; Yoshida, Kazuo*; Yoshinaga, Shinji*; Sato, Kaoru; Ogata, Hiromitsu*; Iwasaki, Toshiharu*; Kudo, Shinichi*; Asada, Kyosei*; Kawaguchi, Isao*; et al.

no journal, , 

Task Group of Low dose and Low Dose Rate Radiation Risk Estimation Method in the Japan Health Physics Society presented the task group activity from April, 2016 to March, 2018. The presenter introduce the current status and issues of dose assessment (e.g. effects of anatomical characteristics of subjects, monitoring data, distribution of dose and dose rate in body on uncertainty of dose assessment).

Oral presentation

Activity report from IRPA Practical Guidance for Engagement with the Public on Radiation and Risk Working Group

Yoshida, Hiroko*; Nomura, Naoki*; Kono, Takahiko; Sakoda, Akihiro; Kuroda, Yujiro*; Naito, Wataru*; Hirota, Seiko*; Kudo, Shinichi*; Takahara, Shogo; Etani, Reo*; et al.

no journal, , 

The WG has translated the "Practical Guidance for Engagement with the Public on Radiation and Risk" ("IRPA Guidance") issued by the International Radiation Protection Association ("IRPA") to its member societies in 2020. "Practical Guidance for Engagement with the Public on Radiation and Risk" (hereinafter referred to as "IRPA Guidance") published by the International Radiological Protection Association (hereinafter referred to as "IRPA") in 2020 for its member societies, and to provide the information to radiation protection experts and other interested.

Oral presentation

Planning session from IRPA Practical Guidance for Engagement with the Public on Radiation and Risk Working Group

Yoshida, Hiroko*; Nomura, Naoki*; Kono, Takahiko; Sakoda, Akihiro; Kuroda, Yujiro*; Naito, Wataru*; Hirota, Seiko*; Kudo, Shinichi*; Kawaguchi, Isao*; Etani, Reo*; et al.

no journal, , 

The WG has translated the "Practical Guidance for Engagement with the Public on Radiation and Risk" ("IRPA Guidance") issued by the International Radiation Protection Association ("IRPA") to its member societies in 2020. "The content of the IRPA guidance was presented at a symposium organized by the Health Physics Society of Japan in June 2020. The content of the IRPA guidance was presented at the Health Physics Society planning symposium held in June 2020, where many experts attended and provided feedback. In this planning session, we will focus on public engagement and related specific examples and situations related to public engagement.

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