RecruitingPhase 1Drug trialAssess Use of 18F-Fluciclovine for Patients With Large Brain Metastases Treated With Staged Stereotactic RadiosurgeryThe spread of cancer to the brain is referred to as brain metastases. Brain metastases are a common complication of cancer. This study is being done to determine whether the use of a new imaging agent, 18F-fluciclovine, is able to detect which patients are responding to radiation therapy. In addition, this study will look at the changes of the treated brain metastases using this imaging agent over time.