Rivers C, et al. - Experts aspired to assess the impact of the number of brain lesions for which stereotactic radiosurgery (SRS) was performed on the dose volume relationships in normal brain. They found no significant relationship of the number of metastatic brain lesions treated with total brain tissue volume treated when using SRS. For establishing guidelines, the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm³ was useful. A significant amount of normal brain tissue could be spared by treating patients with more than 4 lesions with SRS although standard practice had favored using whole brain radiation therapy in these patients. In patients with multiple brain lesions, SRS needed to be carefully considered, with the emphasis on total brain volume involved rather than the number of lesions to be treated.