Initial Deposition Pattern of Actinides 91 to 96 in the Skeleton of the Rat

Within the skeleton the ions of osteophilic metals mostly deposit on bone surfaces. Subsequently, many are rapidly redistributed within bone (Ma62) while others are retained either at or close to their site of deposition. For the purposes of radiation protection dosimetry the radioisotopes of those metals which become redistributed, including those of the alkaline earth elements, have been termed bone-volume seeking radionuclides, whereas those that remain on bone surfaces are described as bone-surface seekers (Ma69 Va73). This distinction is important in radiological protection because the burial of a radioactive metal in the bone matrix effectively shields the radiation sensitive cells, found close to bone surfaces and throughout the bone marrow, from the effects of its decay (ICRP67 ICRP79). Consequently, it is a consistent finding that bone-volume seeking radionuclides are much less toxic, with regard to the production of bone surface related late-effects of radiation including osteosarcomas, than similarly radioactive bone-surface seekers (Va73 May83).