The second goal of this study is to assess a lower dose of brain radiation. Brain radiation may cause memory loss or dementia. For patients over the age of 60, the risk of significant memory loss is 80-90%. The risk for younger patients is smaller but less clear. In this, study patients whose tumors are in remission after chemotherapy will be treated with a lower dose of brain radiation. We hope that this lower dose will be less toxic. However, it is also possible that using a lower dose of radiation will be less effective in controlling your tumor.