Statistical analyses have indicated that there was a significant difference between dogs injected with bone volumeseeking 226Ra as compared to those given bone surface-seeking 239Pu with respect to location within the skeleton of 334 radiation-induced primary bone malignancies. Corresponding differences also were evident when dogs given bone volume-seeking 90Sr or bone surface-seeking 241Am, 228Th, 249,252Cf, or 224Ra (which decays mostly on bone surfaces because of its short, 3.6 d half time) were included along with the 226Ra or 239Pu, respectively (562 total tumors). Further analysis suggested that higher values of percent red marrow (M) and bone turnover rate (R) are correlated with increased probability of tumor appearance at a particular location within the skeleton for the surface seekers. Proportionately higher values of M and R are associated with skeletal sites containing mostly trabecular bone as compared to those with mostly compact (cortical) bone. Coefficients of determination (r2) for the relationship between percent of total tumors vs the combination of percent red marrow and turnover rate (= MR) was about 0.7 for the surface seekers but only about 0.1 for the volume seekers. This indicates that the neoplastic effects of surface seekers, but not volume seekers, are associated with the presence of trabecular bone at the various sites of radionuclide deposition within the skeleton.
(C)1997Health Physics Society