ALTERED-SPLIT DOSE RECOVERY IN MICE IRRADIATED UNDER HYPOXIC CONDITIONS,
Abstract
Mice can be protected from irradiation by exposure to an atmosphere of 5% oxygen, and a dose modifying factor (DMF) of 2.03 is obtained. The amount of injury to the bone marrow appears similar when two-thirds of these LD50's are given, respectively, as indicated by serial white blood cell counts. A significant difference in the recovery patterns was noted after a conditioning dose under hypoxic and air conditions. This was confirmed when a hypoxic conditioning dose was followed by re-determination of the LD50 in air. Comparison of these patterns leads to the conclusion that early repair at the cellular level is diminished after irradiation under hypoxic conditions in this particular cell type. There is also evidence that the onset of regeneration is delayed. Multiple exposure data and calculated dose modifying factors for the split-dose situation indicate that a maximum reduction in the DMF from 2.03 to 1.53 can be attained. This reduction in DMF with multiple exposures has significance for radiation therapy since it indicates that fractionated radiation therapy may obviate some of the problems encountered when a portion of a tumor is hypoxic. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 26, 1968
- Accession Number
- AD0675781
Entities
People
- E. John Ainsworth
- Theodore L. Phillips
Organizations
- Naval Radiological Defense Laboratory