Irradiation of the Gastrointestinal Tract of the Rat by Ingested Ruthenium-106

Rats were killed at intervals from 35 minutes to 30 hours following intragastric administration of a solution of Ru106 chloride. Distribution of Ru106 within the various segments of the gastrointestinal tract, and distribution of tract contents were determined. Results are interpreted in terms of the rate of passage of material through the gastrointestinal tract, and the resulting radiation dose to the various segments of the tract. The largest radiation dose is delivered to the lower large intestine. Doses to other segments of the tract are lower by as much as a factor of five. There appears to be no significant hold-up of the radioisotope due to absorption on the intestinal wall.