Granulocyte changes in 17 patients who are characteristic for a grading code H4 observed in 6 radiation accidents caused by whole body exposure to pure gamma or a mixed neutron/gamma radiation. An irreversible injury to the bone marrow stem cell pool can be assumed if the pattern of granulocyte concentration changes shows a severe granulocytopenia on days 5/6 (grade H4). However, the “dose” was reported to range from 8 to 20 Gy (median 11 Gy). A computerized program is under development to assess blood cell changes early after exposure and calculate the assignment of a patient to a grade H. The cases are documented in the database system SEARCH5 and have been analyzed scientifically.4,6-8 This figure was presented at the RITN meeting on September 25, 2007, in Bethesda, MD.
