Effects of dose fractionation on late roentgen radiation damage of rat small intestine.
In female Wistar rats a 10 cm long exteriorized mid small intestinal segment was roentgen irradiated. Nominal standard radiation doses were 17 and 19 Gy, given as a single exposure and in 2 and 3 fractions with intervals of 48 hours. Animals were killed and examined in groups of 3 every 6 weeks from 8 to 44 weeks following irradiation. Macroscopic and histopathologic parameters of irradiation injury were used to calculate an injury score for each animal. In the 2 fractions group both mortality and irradiation injury score were higher than in the single exposure and 3 fractions groups. The difference was due in particular to persisting mucosal ulcerations and epithelial atypia. Adenocarcinoma of the irradiated intestine was found in 4 animals.
D000230:Adenocarcinoma / Q000209:etiology; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007421:Intestine, Small / Q000473:pathology / Q000528:radiation effects*; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains