We used the dose of exposure to radiation from neutrons and gamma rays estimated by using the Atomic Bomb Survivor 1993 Dose (ABS93D). ABS93D was described in detail in a previous report (28 (link)). Briefly, radiation dose calculated by ABS93D is based on individual exposure status such as distance from the hypocenter, shielding and age at time of bombing. Hoshi et al. (28 (link)) showed that the dose evaluation of ABS93D was close to that of the Dosimetry system 1986 (DS86) by Radiation Effects Research Foundation. We used the weighted radiation dose of the colon, which is often chosen as the whole-body irradiation exemplary organ, by calculating the sum of the gamma ray dose and 10 times the neutron dose considering the biological effectiveness of neutrons.
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