EXPERIMENTAL ARTERIAL LESIONS AFTER NARROW-BEAM GAMMA-IRRADIATION USED IN STEREOTACTIC RADIOSURGERY

An experimental study on rats showing the arterial lesions caused by t he beams of gamma irradiation used in stereotactic radiosurgery is pre sented. The common carotid artery of the rat was irradiated with a sin gle narrow-beam of gamma radiation with a maximum dose of 30 and 60 Gy . The results were evaluated at 4, 12 and 24 weeks after irradiation. Several focal changes in the arterial walls were observed in all perio ds of study with a predominance of hyperplastic (proliferative) altera tions at doses of 30 Gy, and hyaline degeneration at doses of 60 Gy. T otal occlusion was not observed in any case. In conclusion, vascular h yperplasia is more prominent with the lower doses evaluated.