Microdistribution and local dosimetry of /sup 226/Ra in trabecular bone of the beagle
Sections of lumbar vertebral bodies of young adult beagle dogs have been analyzed autoradiographically to characterize and quantify the local distribution of 226Ra by means of a scanning microscope photometer. The animals received a single injection of 355 kBq/kg body weight and were serially sacrificed at 5 to 1381 days postinjection. Hotspot concentrations decreased from about 51 kBq/g bone at 5 days to 20 kBq/g at 1381 days postinjection. The diffuse concentration changed from 8.3 to 1.9 kBq/g. The mean 226Ra concentration in the trabecular areas scanned was initially higher and at the end of the observation period lower than the average calculated for the whole lumbar vertebral column. Density and area of, and fraction of bone activity in, hotspots virtually remained constant. With time hotspots tended to become translocated into bone volume. Mean dose rates to lining cells from both hotspots and diffuse labels decreased from about 210 mGy/d at early postinjection times to 105 mGy/d. This corresponds to 2.5 to 1.1 times the average skeletal dose rate. A discussion of the level of irradiation in terms of hit frequencies shows that osteoblasts in the initial phase of hotspot formation receive about 60 hits to their nucleus for the duration of bone formation. After about 6 months, however, the 226Ra concentration in new bone and the corresponding hit frequency appears to be low enough that interference with bone formation is unlikely. Morphometric measurements showed that abnormal bone accretion and thickening of trabeculae occurred. This was interpreted as an imbalance between bone formation and resorption. Both formation and resorption seem to be substantially lowered compared to control animals.
- Research Organization:
- Institut fuer Genetik und Toxikologie von Spaltstoffen, Karlsruhe (West Germany)
- OSTI ID:
- 6579615
- Journal Information:
- Radiat. Res.; (United States), Vol. 116:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RADIUM 226
TISSUE DISTRIBUTION
SKELETON
RADIONUCLIDE KINETICS
AUTORADIOGRAPHY
BEAGLES
RADIATION DOSES
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
ANIMALS
BODY
CARBON 14 DECAY RADIOISOTOPES
DISTRIBUTION
DOGS
DOSES
EVEN-EVEN NUCLEI
HEAVY NUCLEI
ISOTOPES
MAMMALS
NUCLEI
ORGANS
RADIOISOTOPES
RADIUM ISOTOPES
VERTEBRATES
YEARS LIVING RADIOISOTOPES
560162* - Radionuclide Effects
Kinetics
& Toxicology- Animals
Plants
Microorganisms
& Cells