90Sr-90Y Dose Distribution in Beagles

Abstract

The Yir body burden ingested as a constant fraction of dietary calcium in 1.5 yr goSr-goY feeding was analyzed for uptake and retention. Retention times were compared to that for a single intravenous injection of at to = 1.5 yr of age ( t ) . The uptake parameters were compared with skeletal and body growth rates. No significant differences in body weight pattern of 452 beagles were observed between the controls and gOSr-fed dogs. The retention parameters in our singly injected beagles were compared with those for 90Sr inhalation studies;no difference was observed. The average skeletal dose rate bo(t) and the time-integrated dose Do(t) were calculated from the mean body burden as a function of age and skeletal/body weight ratios. The local dose was determined by a combination of thermoluminescent dosimetry and measurement ofgoSr concentration. The local dose rate b(t) was corrected for local bone geometry and local distribution ofwSr activities. The local dose rates and dose were compared to the average skeletal dose and dose rate. The local dose to marrow at the proximal humerus was always overestimated by the average skeletal dose and dose rate. The dose rate fjo(t) overestimated the dose to hematopoietic tissue for the first 5 yr of life partially due to averaging of the higher gOSr concentration in cortical bone with the lower concentration in trabecular bones.The Do(t) overestimated D(1) at the cortical regions for all t . Autoradiographic and local measurement of 90Sr in bone revealed that a uniformly labeled skeleton (constant goSr/g of ash) was obtained in 1.5 yr of feeding. For periods t > to the fast local turnover at the proximal region relative to cortical bone produced "cold spots" and low activity regions of cancellous bone. In contrast, the injected cortical bones showed hot spot areas on a diffuse background.

Dose Rates, Dose and Time Effects of 90Sr + 90Y and 226Ra on Beagle Skeleton

“…The details of the experimental design for long-term toxicity and metabolism ofSoSr + and 226Ra in beagles at the Radiobiology Laboratory, University of California at Davis, have been published (MOMENI et al, 1975(MOMENI et al, , 1976aDELLA ROSA et al, 1965, GOLDMAN et al, 1969a, b, 1972. In summary, SoSrC12, in equilibrium with SOY, was fed to dogs mixed with their diet, from midgestation to young adulthood (1.5 yr of age).…”

“…In summary, SoSrC12, in equilibrium with SOY, was fed to dogs mixed with their diet, from midgestation to young adulthood (1.5 yr of age). For each dose level, a constant ratio of strontium to calcium in the diet was maintained (MOMENI et al, 1976a). For each dose level, a constant ratio of strontium to calcium in the diet was maintained (MOMENI et al, 1976a).…”

“…90Sr + is continuously incorporated within the skeletal matrix from fetal ossification to maturity, creating a uniform radioactivity distribution in spongy and cortical bone (MOMENI et al, 1976a). For example, the pattern of dietary OOSr + dose distribution in the skeleton is completely different from that of injected 2zGRa.…”

“…DOSE AND TIME EFFECTS OF WSr + SOY AND 226Ra ON BEAGLE SKELETON or a daily diet of the radionuclides (in utero to 18 months of age) has been reported (MOMENI et al, 1975(MOMENI et al, , 1976a. Retention, local distribution, and dosimetry of 2z6Ra in humeri and in the skeleton of beagles given 8 semimonthly intravenous 226Ra injections started at 2 months, 4 months and 14 months of age has been also reported (MOMENI et al, 1973(MOMENI et al, , 1974(MOMENI et al, , 1976b.…”