There are two types of localized brain radiation therapy; both aim to spare normal brain tissue: Conformal: Using CT to create a 3-dimensional map of the tumor facilitates precise targeting of the tumor Stereotactic: Using gamma knife or proton beam therapy to deliver multiple focused beams of high energy to the tumor Gliomas are treated with conformal radiation therapy; a stereotactically directed gamma knife or proton beam therapy is useful for metastases.