Progress on the dosimetry of bone surface seeking radionuclides

The main features of a proposed generalised dosimetric model used to define the deposition and translocation of alpha and beta-emitting radionuclides within the skeleton are outlined. This model has been used to calculate the values of the absorbed fractions for the alpha-emitting isotopes of uranium, plutonium and americium and for some beta-emitting actinide and lanthanide isotopes. In comparison to the equivalent values recommended for use by ICRP, these calculated values for most of the isotopes are lower than the ICRP fractions. Thus if the calculated values for these radionuclides were substituted in the ICRP models to calculate annual limits on intake, the limits would be less restrictive than the ICRP recommended ALIs. Some exceptions are also discussed. (U.K.)