Hematopoietic cell renewal as the limiting factor in low-level radiation exposure: diagnostic implications and therapeutic options.
In some radiation accidents, exposure doses are delivered over days or even months. In all cases the organ system most relevant to a patient's survival is the hematopoietic tissue. There appears to be a threshold of approximately 10 mSv per day above which hematopoietic effects become apparent and hematopoietic failure may occur. Experimental observations in dogs demonstrate that exposure to chronic gamma-irradiation may be tolerated for over a year if the daily dose does not exceed 7 mSv to 18 mSv. The pathophysiological mechanisms are being studied by hematological measures and biomathematical models. The results are in accordance with the assumption of excess cell loss and progressive diminution of the stem cell pool over time until a "turbulence region," with an increased probability of system failure, is approached. Diagnostic procedures require a thorough hematological assessment that includes the stem cell compartment. Therapeutic options include administration of hematopoietic growth factors and stem cell transplantation.
Fliedner
Theodor M
TM
Radiation Medicine Research Group, WHO Collaborating Center for Radiation Accident Management, Faculty of Medicine, University of Ulm, Helmholtzstrasse 20, D-89081 Ulm, Germany.
Friesecke
Iris
I
Graessle
Dieter
D
Paulsen
Carola
C
Weiss
Melanie
M
D000818:Animals; D004285:Dogs; D006412:Hematopoietic Stem Cells / Q000528:radiation effects*; D006801:Humans; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000473:pathology*; D018788:Radioactive Hazard Release