RATIONALE: Cotara® is an experimental new treatment that links a radioactive isotope (iodine 131) to a targeted monoclonal antibody. This monoclonal antibody is designed to bind tumor cells and deliver radiation directly to the center of the tumor mass while minimizing effects on normal tissues. Cotara® thus literally destroys the tumor "from the inside out." This may be an effective treatment for glioblastoma multiforme, a malignant type of brain cancer.