Temporal change in microdosimetry on bone marrow and stromal progenitor cells from alpha-particle-emitting radionuclides incorporated in bone

The microdistributions of the alpha-particle-emitting bone surface-seeking radionuclides Pu-239, Am-241 and U-233 in the mouse femoral shaft have been studied using computer-based image analysis of neutron-induced and alpha-p article track autoradiographs, prepared from femora of CBA/H mice which had been injected with 40 kBq kg(-1) of radionuclide (as citrate solution) at times from 1 to 448 days previously. Employing dosimetric methods, radiatio n dose rates and cumulative radiation doses to regions of the bone marrow t hought to contain hemopoietic and stromal progenitor cells susceptible to n eoplastic transformation to leukemia and osteosarcomas have been calculated , It has been shown that the three radionuclides differ in their relative d eposition on the bone surfaces, and that patterns of changing redistributio n with time are also varied. For stromal progenitor cells, which are though t to be targets for induction of osteosarcoma and are found in proximity to the bone surfaces, cumulative doses showed the trend (PU)-P-239 > Am-241 > U-233, correlating well with incidences of osteosarcoma observed in mice. Cumulative doses to the primitive hemopoietic stem cells, concentrated in t he central marrow and thought to be susceptible to neoplastic transformatio n to myloid leukemia, were considerably lower and also showed the trend plu tonium > americium > uranium. (C) 1999 by Radiation Research Society.