Intestinal weight loss in mice irradiated by roentgen rays, gamma rays, and fast neutrons

Groups of l0-week-old female RF mice were exposed to graded doses of Co/ sup 60/ gamma rays 250 kv x rays, or l4-Mev fast neutrons. The weight of the small intestine decreased during the first 48 hours after irradiation as a linear function of dose over the range 50 to 700 rads. No significant differences between radiations in the production of this effect were observed l day after irradiation, but at 2 days the RBE was found to increase with LET, being l.0, l.5, and 2.0 for gamma rays. x rays, and neutrons, respectively. The RBE of neutrons for intestinal weight loss was appreciably higher than for 30-day lethality, in keeping with the hypothesis that the earlier mortality of mice exposed to neutrons, as opposed to roentgen rays, results from relatively greater injury of the gastrointestinal tract by neutrons. (auth)