Effect of different daily rate of continuous irradiation upon changes in cfu number

The effect of continuous irradiation upon colony-forming capacity of bone marrow cells was studied in mice exposed continuously for the length of 130 days to ionizing radiation at exposure rates ranging from 1--50R per day. A stabilized state in CFU number was observed between days 30 and 100, its level being related solely to the daily exposure rate. An interpolation of data on CFU found on days 30, 40, 50, 60, 70, 80, 90, and 100 provided an exponential curve which can be characterized by the equation log y = a + bx + cx2. This equation can be applied to prognostic estimation of CFU level during the stabilized state between days 30 and 100 of continuous radiation exposure at rates ranging from 1--50R day.