DOSE-VOLUME CONSIDERATIONS IN RADIOSURGERY

Dose-volume effects are very important in radiosurgery. Functional radiosurgery illustrates brain tolerance at the extremes of small volumes and high radiation doses. The risks of radiation necrosis from radiosurgery of arteriovenous malformations (AVMs) and tumors appear to be reasonably well predicted by the integrated logistic formula and the 1% dose-volume isoeffect line for proton beam irradiation. The two main exceptions to this rule are cranial nerves, which appear to be more sensitive than the rest of the brain, and angiographically occult vascular malformations, where complications appear to occur at lower doses/volumes than in the treatment of tumors or AVMs. Further investigation is needed to better predict complications throughout the entire range of volumes, radiation doses, treatment locations and techniques presently used in stereotactic radiosurgery.