Radiation Dosimetry of Internal Contamination by Inorganic Compounds of Cobalt

Abstract

The whole body retention of cobalt during a period of 400 days after injection of CoCl2 has been determined for a strain of specific-pathogen-free albino rats. The method used to fit both exponential and power functions to the data and the application of statistical tests which justify the selection of a function with five exponential terms as the best fit are described. The statistical methods used in this paper are presented in detail because of their possible application to other studies of a similar nature. The amounts of cobalt in 19 tissues have been measured at various times and expressed as concentration factors, which were found to be stable during the period between 10 and 72 days after injection. However, the concentration factor of bone increased during a period of 400 days at the expense of the concentrations in the soft tissues. The function developed to describe the whole body retention of cobalt is substantially different from that selected in ICRP Publication 10 and examples of the consequences of applying the two functions to the radiation dosimetry of internal contamination by 60CoCl2 are given. The selection of critical organs for radioisotopes of cobalt is also discussed.