Determinations of Organ or Tissue Doses to Survivors in Hiroshima and Nagasaki

Abstract

For the purpose of risk estimates from radiation carcinogenesis including leukemogenesis and radiation genetic effects, the biological significant dose is not the tissue kerma in air but the absorbed dose in organ or tissue with respect to carcinogenic and leukemogenic effects or genetic effects. In order to estimate organ or tissue dose from the tissue kerma in air, a ratio of the organ or tissue dose to the tissue kerma in air for survivors in Hiroshima and Nagasaki was calcuated with the aid of the Snyder's mathematical phantoms constructed so as to simulate the body shape of survivors aged 5, 10 years old and adult at the time of atomic bomb detonations. The ratios were corrected for the angular distribution of atomic bomb radiations, assuming an anisotropic angular distribution for the survivors exposed to the atomic bombs in open air and the isotropic distribution for the survivors incide a Japanese house or other structures.
The resultant ratios are tabulated as a function of incident angles on survivors for gammarays and neutrons. The ratios for neutrons were categorized according to the type of interaction of neutrons with tissue elements. It is noted that the ratios for survivors exposed as children and juveniles were significantly higher than those for survivors exposed as adults.