Measure of blood flow by the multiple radioactive microsphere technique in radiated gastrointestinal tissue

In this study, two different radioactive microspheres were used to measure blood flow of an irradiated segment of small intestine in four dogs before, and 12 days after, irradiation with 2000 rad. The technique and implications are discussed. Using multiple radioactive microspheres, the study demonstrated an increased blood flow in irradiated tissues twelve days after a single dose of 2000 rad. There was also an increase in blood flow to adjoining nonradiated segments of intestine in the same animal. These observations may be of significance in clinical applications of radiation therapy and surgery. A major surgical concern is the impaired healing of irradiated tissue in the immediate postradiation period. The mechanism of this has generally implicated decreases in the perfusion of irradiated tissue. No decrease in blood flow was shown in this study, suggesting that other mechanisms, e.g., stem cell depletion, should be considered. Further studies of this type are recommended to increase understanding of the blood flow in irradiated tissue.