Brief note and evaluation of acute-radiation syndrome and treatment of a Tokai-mura criticality accident patient.

Patient A who was exposed to a critical dose of radiation developed skin lesions throughout the body surface, gastrointestinal disorder with massive diarrhea and prominent bleeding, which caused severe loss in body fluids. Gastrointestinal bleeding due to the deteriorated intestinal mucosa was considered to be one of the major causes of death, although infection did not develop, possibly because of SDD and aseptic intensive care, until terminal stages. Patient A ultimately developed respiratory and renal failure in addition to skin exudate and gastrointestinal bleeding, and died of multiple organ failure on the 83rd day after exposure. The extreme unevenness of the dose distribution and the neutron versus y-ray component made the clinical manifestation very complicated. Initially, the mean absorbed dose was calculated as 16-20 GyEq for Patient A, mainly based on neutron-activated 24Na in the blood. However, a very recent calculation showed that the absorbed skin dose was highest at the upper-right abdomen reaching 61.8 Gy (27.0 as neutron plus 34.8 Gy as y-ray). The dorsal side was calculated to have received one eighth of the value of the abdominal side, and much smaller neutron component. His absorbed-dose distribution throughout the body was very inhomogeneous because of the closeness of the standing point to the mixing tank. Despite prolonged survival because of intensive care with massive fluids and blood transfusion, peripheral blood stem-cell transplantation, cultured skin-cell grafts, and the administration of cytokines for marrow, the patient was not saved. Restoration of the bone marrow function, prevention of skin fibrosis, radiation lung damage, and repair of gastrointestinal mucosa, and final recovery of the patient were elusive. Abundant personnel and resources were also a prerequisite to allow for the comprehensive and collective intensive care. A further understanding of the effects of high-dose radiation as well as the basic and clinical development of regeneration medicine are important issues for the future.