The Atomic Bomb Casualty Commission (ABCC) has radiation exposure estimates for most of the 117,000 A-bomb survivors in the Master Sample; however, these estimates, denoted T65D (CHEKA, 1965; NOBLE, 1967; HUBBELL, 1960), actually predict absorbed dose or kerma to infinitesimal amounts of biological tissue under exact analogue exposure conditions, except for the absence of the specific survivors. The kerma represents the kinetic energy released in materials and becomes equal to the absorbed dose if, and only if, all energy released when a particle interacts is assumed to be locally deposited, i.e. the pathlengths of the secondary particles are short in comparison to the dimensions of the critical biological organs. These estimates, often referred to as “T65D doses,” are inadequate to assess the radiation insult to a survivor or to a critical biological organ of the survivor, because they neglect the attenuation and multiple scattering by the body of the survivor. “It must also be clearly borne in mind that absorbed doses, particularly to deep tissues, are difficult to obtain from the kerma estimates available” (UNSCEAR, 1972). In the present work, a method is provided to use the “T65D doses,” or incident neutron radiation and incident photon radiation, to estimate dose to an organ such as the thyroid gland or to a specific site of interest such as the isthmus of the thyroid gland or even to survivors who were in utero at the time of exposure. The method also permits the assessment of the additional radiation insult from photons produced by neutron interactions in the body. Estimates of absorbed doses to specific organs, especially deep seated organs within the body, will allow for more accurate estimates of risk.