DYNAMIC RADIONUCLIDE LABELS AT SITES OF BONE-FORMATION IN THE SKELETON

The mean dose and number of hits to nuclei of osteoblasts and their progenitors from expanding volume sources of alpha-emitters labelling newly formed bone is calculated. It is assumed that these cells only accumulate a radiation dose or nuclear hits during a formation phase. For alpha-emitters below 6 MeV the dose or number of hits per unit concentration is nearly identical for constant or decreasing mineralisation rate. By means of a simple biokinetic model the amount of recirculating activity and the concentration in sites of bone formation is estimated and results compared with a human injection case. Annual limiting intake levels recommended by ICRP for some transuranics appear to be safe with regard to radiation doses and hit probabilities in formation sites.