One of the primary reasons to deliver radiation in multiple small doses conventionally (30-33 treatments over 6-61/2 weeks) is to minimize damage to the surrounding normal brain. The Cyberknife technology allows precise delivery of radiation to your tumor while minimizing radiation to the surrounding brain. This allows the possibility of delivering higher doses of radiation to the tumor thereby shortening the overall treatment time (18 treatments in 31/2 weeks). This is what is being studied in this study.