Radiobiology of Large Animals.
Abstract
Significant accumulation of radiation injury in sheep continuously irradiated (Cobalt 60) at dose rates of less than 1 R/hr has been demonstrated. The estimated LD50/60 at 0.91 R/hr is 1277 R, while the amount of residual injury after an accumulated exposure of 727 R at 0.46 R/hr is indicative of an LD50/60 of 1957 R. Increasing the dose rate to 3.4 R/hr, with simultaneous reduction in exposure time so that incremental weekly doses (140 R) remain the same as at 0.91 R/hr, results in a significant lowering of the estimated LD50/60 to 1054 R. Combined analysis of previous results from a kinetic standpoint indicates that counts of circulating leucocytes in the sheep are not primarily determined by the size of the parent stemcell population. In addition, it has been found that hematologic measures in the sheep tend to show marked departures from the normal distribution. Finally, radioactive tracer studies have shown that the total bone-marrow cellularity per kilogram of body weight is similar in mice and in sheep. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1971
- Accession Number
- AD0731501
Entities
People
- David C. L. Jones
- John S. Krebs
Organizations
- SRI International