Hematological studies of six cases of accidental exposure to an iridium radiographic source

Among six persons (male, age 20-30) exposed accidentally to 192Ir gamma-rays, five cases showd hematopoietic disorders of various degrees. One case (S. H. 25 Yr.) showed a severe hematopoietic injury such as pancytopenia between the 3rd and 7th week after the initial exposure. On the 4th and 5th week, thrombelastogram showed an earliest and significant improvement, followed by increase of leukocyte and platelet counts. This clinical test was useful for diagnosis and prognostic evaluation in this crucial pancytopenic period during which some treatments or cares were needed. He was treated only with a prophylactic administration of antibiotics in an isolated clean aseptic room. Since 5th week, the hematopoietic disorders were rapidly improved although the leukocyte counts still remained at a subnormal level for more than 18 months. The other 4 cases showed various degrees of temporal leukopenia and hypoplasia of bone marrow, while neither anemia nor thrombocytopenia was observed. From the severity of hematopoietic disorders, a dose delivered to hematopoietic organs of S. H. was estimated to be somewhat between 200 and 400 rad. This was different from a cytogenetically estimated dose of 124 rad. The difference may mainly reflect a difference of doses received between hematopoietic cells and of peripheral circulating lymphocytes, which might be resulted from a different distribution of these cells in the body and from a non-uniform gammarays irradiation of 192Ir source.