Atomic bomb dosimetry for epidemiological studies of survivors in Hiroshima and Nagasaki

Better atomic bomb (A-bomb) radiation dose estimates with a higher accuracy are required for the epidemiological studies in Hiroshima and Nagasaki. Several scientists have tried to evaluate the free-in-air gamma ray and neutron dose and some weighting factors such as house shielding and body shielding. Since 1965, the tentative 1965 dose (T65D) had been widely used as the basic data for the dose determination of A-bomb survivors in epidemiological studies. In 1976, however, the reevaluation of the T65D dose was proposed by an American scientist who calculated the A-bomb doses on the basis of declassified data on the radiation spectra of the A-bomb. The development of computer technology made it possible to perform complicated dosecalculations for the Hiroshima and Nagasaki bombs. This paper describes the history of A-bomb dosimetry, reviews some issues in the determination of T65D, and discusses the necessity of reassessment of A-bomb dose and the expected values for survivors