Acute brain damage induced by x‐irradiation with special reference to rate and recovery factors

Abstract

Rats received limited head X-irradiation of 3,000 r delivered at the following dose rates 930 r, 600 r, 300 r, and 150 r per minute. No consistent alterations at the several dose rate or time intervals were noted 1, 6, 24 and 48 hours postirradiation. Cerebellar granule cells were pynknotic. The severest response was elicited at 930 r and 600 r, becoming more pronounced from 1 to 24 hours after radiation. Rossman-fixed material from animals that received 930 r and 600 r demonstrated fine particulate granules of diastase digestible PAS-positive material scattered throughout the neuropil. Acute swelling of oligo-dendroglia leading to necrosis reached a maximum 6 to 24 hours after radiation, irrespective of dose rate. At the 95% level of confidence, there was no significant difference between the damaged oligodendro-cytes of the brain stem and those of the cerebral cortex. There was a significant difference between the damaged oligodendrocytes of the cerebellum and those of both the brain stem and the cerebral cortex. The over-all analysis showed that the time and the dose rate were significant at the 95% level. This effect is significant out to the 3rd degree in time and the 2nd degree in dose rate.