Histologic Effects of Total-Body X-Irradiation in Various Dose Fractionation Patterns on Fetal Cerebral Hemisphere

Publisher Website
Google Scholar
Abstract
Albino rats of the Sprague-Dawley strain were exposed to 150 R of whole-body X-irradiation on gestation days 13.5 and 14.0 in single doses and in several dose fractionation patterns within the 12-hour period. Residual tissue damage in olfactory bulbs, parolfactory areas, striatum, and primordial ependymal and cortical layers on gestation day 19.5 was heaviest in single-dose rats and decreased progressively in rats that received two 75-R exposures at l-,3-,6-,9-, or 12-hour intervals. No significant difference in effect was observed in animals receiving a single exposure on day 13.5 or on day 14.0. The severity of histological damage also decreased progressively in animals that received the total 150-R dose in 2,3,5, or 9 equal fractions over the 12-hour period, and was less in the multiple-fraction animals than in the variable-interval group. It is concluded that size of the individual fractions is more important than the number of fractions at a specific total dose level over a given time period in determining severity of residual histological alterations resulting from dose fractionation regimens, and that residual tissue damage decreases progressively with increasing interval between two dose fractions from 1 to 12 hours.