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Sasaki, Michiya*; Furukawa, Kyoji*; Satoh, Daiki; Shimada, Kazumasa; Kudo, Shinichi*; Takagi, Shunji*; Takahara, Shogo; Kai, Michiaki*
Journal of Radiation Protection and Research, 48(2), p.90 - 99, 2023/06
This paper reports on the calculation code that is the result of the activities of the "Task Group for Development of Cancer Risk Estimation Codes Associated with Radiation Exposure (FY2020-2021)" established by the Japan Health Physics Society. In order to promote research on the estimation of cancer risk associated with radiation exposure, the Task Group decided to disclose the source code, including the algorithm and parameters used in the calculations, and to release the code under a license that permits modification and redistribution of the code. The computational code was named SUMRAY and coded in two computer languages, that is R and Python. The code is capable of calculating the accumulated excess risk using Monte Carlo methods with a 95% confidence interval. The results of SUMRAY were compared with the results of the existing codes whose source code is not publicly available, under the same calculation conditions. From the results, it was found that they were in reasonable agreement within the confidence interval. It is expected that SUMRAY, an open-source software, will be used as a common basis for cancer risk estimation studies associated with radiation exposure.
Yasuoka, Yumi*; Fujita, Hiroki; Tsuji, Tomoya; Tsujiguchi, Takakiyo*; Sasaki, Michiya*; Miyazaki, Tomoyuki*; Hashima, Shun*; Yasuda, Hiroshi*; Shimada, Kazumasa; Hirota, Seiko*
Hoken Butsuri (Internet), 57(3), p.146 - 155, 2022/12
no abstracts in English
Nugraha, E. D.*; Hosoda, Masahiro*; Kusdiana*; Untara*; Mellawati, J.*; Nurokhim*; Tamakuma, Yuki*; Ikram, A.*; Syaifudin, M.*; Yamada, Ryohei; et al.
Scientific Reports (Internet), 11(1), p.14578_1 - 14578_16, 2021/07
Times Cited Count：19 Percentile：84.25(Multidisciplinary Sciences)Mamuju is one of the regions in Indonesia which retains natural conditions but has relatively high exposure to natural radiation. The goals of the present study were to characterize exposure of the entire Mamuju region as a high natural background radiation area (HNBRA) and to assess the existing exposure as a means for radiation protection of the public and the environment. A cross-sectional study method was used with cluster sampling areas by measuring all parameters that contribute to external and internal radiation exposures. It was determined that Mamuju was a unique HNBRA with the annual effective dose between 17 and 115 mSv, with an average of 32 mSv. The lifetime cumulative dose calculation suggested that Mamuju residents could receive as much as 2.2 Sv on average which is much higher than the average dose of atomic bomb survivors for which risks of cancer and non-cancer diseases are demonstrated. The study results are new scientific data allowing better understanding of health effects related to chronic low-dose-rate radiation exposure and they can be used as the main input in a future epidemiology study.
Hosoda, Masahiro*; Nugraha, E. D.*; Akata, Naofumi*; Yamada, Ryohei; Tamakuma, Yuki*; Sasaki, Michiya*; Kelleher, K.*; Yoshinaga, Shinji*; Suzuki, Takahito*; Rattanapongs, C. P.*; et al.
Science of the Total Environment, 750, p.142346_1 - 142346_11, 2021/01
Times Cited Count：23 Percentile：86.19(Environmental Sciences)The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures. We aimed to estimate the comprehensive dose due to internal and external exposures at the particularly high natural radiation area, and to discuss the enhancement mechanism of radon. A car-borne survey was conducted to estimate the external doses from terrestrial radiation. Indoor radon measurements were made in 47 dwellings over three to five months, covering the two typical seasons, to estimate the internal doses. Atmospheric radon gases were simultaneously collected at several heights to evaluate the vertical distribution. The absorbed dose rates in air in the study area vary widely between 50 nGy h
and 1109 nGy h. Indoor radon concentrations ranged from 124 Bq m
to 1015 Bq m. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m recommended by the World Health Organization. Furthermore, the outdoor radon concentrations measured were comparable to the high indoor radon concentrations. The annual effective dose due to external and internal exposures in the study area was estimated to be 27 mSv using the median values. It was found that many residents are receiving radiation exposure from natural radionuclides over the dose limit for occupational exposure to radiation workers. This enhanced outdoor radon concentration might be as a result of the stable atmospheric conditions generated at an exceptionally low altitude. Our findings suggest that this area provides a unique opportunity to conduct an epidemiological study related to health effects due to chronic low dose-rate radiation exposure.
Sasaki, Michiya*; Nunomiya, Tomoya*; Nakamura, Takashi*; Nakao, Noriaki*; Shibata, Tokushi*; Nakane, Yoshihiro; Tanaka, Susumu
JAERI-Review 2000-024, TIARA Annual Report 1999, p.259 - 261, 2000/10
no abstracts in English
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).
Sasaki, Michiya*; Yamada, Ryohei; Akata, Naofumi*; Tokonami, Shinji*; Hosoda, Masahiro*; Iwaoka, Kazuki*; Chanis, P.*; Kudo, Hiromi*; Sahoo, K.*; Iskandar, D.*; et al.
no journal, ,
Recently, Mamuju city in Sulawesi Island, Indonesia and its surrounding area is known as the high background radiation area, and is regarded as a possible area for an epidemiological study. In this study we have measured the hourly dose rates of individuals and the environment with the D-shuttle dosimeter, which has been developed by the Chiyoda Technol Corporation. With the aid of local residents living at Botteng village, which is located south of Mamuju city, short term and long term measurements were conducted for three days and nine months, respectively. Two volunteers have equipped the D-shuttle for the short term measurement, and seven families supported the short and long term measurements of the environmental dose rate, for both inside and outside the house. From our results, since some variation was observed regarding with day or night, correlation with radon concentration was suggested.
Sasaki, Michiya*; Yamada, Ryohei; Nugraha, E.*; Akata, Naofumi*; Tokonami, Shinji*; Hosoda, Masahiro*; Iwaoka, Kazuki*; Pornnumpa, C.*; Kudo, Hiromi*; Sahoo, K.*; et al.
no journal, ,
The area around Mamuju city in West Sulawesi, Indonesia has high possibility of being a target of epidemiological research as a high natural radiation area. We would like to report the difference in radiation dose at different heights from the ground measured by the D-Shuttle.
Sasaki, Michiya*; Takagi, Shunji*; Kai, Michiaki*; Furukawa, Kyoji*; Kawaguchi, Isao*; Kudo, Shinichi*; Takahara, Shogo; Otoshi, Kazuki*; Shimada, Kazumasa; Satoh, Daiki
no journal, ,
To contribute to the quantitative discussion of risks associated with low-dose radiation exposure, the Japan Society of Health Physics established the "Task Group for the Development of Estimation Codes for Cancer Risk caused by Radiation Exposure". This presentation will report on the activities conducted during the two-year period from FY2020 to FY2021.
Satoh, Daiki; Sasaki, Michiya*; Furukawa, Kyoji*; Shimada, Kazumasa; Kudo, Shinichi*; Takahara, Shogo; Takagi, Shunji*; Kai, Michiaki*
no journal, ,
no abstracts in English
Sasaki, Michiya*; Furukawa, Kyoji*; Satoh, Daiki; Shimada, Kazumasa; Kudo, Shinichi*; Takahara, Shogo; Takagi, Shunji*; Kai, Michiaki*
no journal, ,
no abstracts in English
Kai, Michiaki*; Shimada, Kazumasa; Kudo, Shinichi*; Furukawa, Kyoji*; Satoh, Daiki; Takahara, Shogo; Takagi, Shunji*; Sasaki, Michiya*
no journal, ,
This presentation is the third in a series of three presentations on the results of the "Expert Group on the Development of Cancer Risk Estimation Codes Associated with Radiation Exposure" established by the Japan Health Physics Society, which examines the parameters employed in the codes and the calculation results, and summarizes the future prospects of the codes. In order to calculate cumulative excess risk (CER) as a measure of lifetime risk with confidence intervals, a variance-covariance matrix for the parameters of the risk model is required. However, in a study conducted by the Radiation Effects Research Foundation using the regression analysis program Epicure on large-scale epidemiological data from A-bomb survivors, the variance-covariance matrix was not disclosed. Therefore, in this study, we independently derived parameters and covariance matrices using a generalized linear model (GLM) and confirmed that the parameter values agreed well with the Epicure results. The CERs calculated using the derived parameters and covariance matrices were compared with those calculated by the U.S. code RadRAT. Although a simple comparison is not possible due to the different population baselines of the two codes, they were found to be in general agreement. The developed code is expected to contribute to the discussion of influence factors and uncertainty in risk assessment.
