Brain metastases are the most common adult intracranial tumor, occurring in approximately 10% to 30% of adult cancer patients, and represent an important cause of morbidity and mortality. The most widely used treatment for patients with multiple brain metastases is whole brain radiation therapy (WBRT). The use of WBRT after resection or stereotactic radiosurgery (SRS) has been proven to be effective in terms of improving local control of brain metastases.

RapidArc (RA) (Varian Medical Systems, Palo Alto, CA) is a new method of delivering radiation that uses "arcs" to deliver highly conformal intensity modulated three dimensional dose distributions. The purpose of this investigation is to evaluate an alternative strategy for giving WBRT with highly focal boost to gross visible lesions in patients with brain metastasis.

In this study, the investigators plan to assess the tolerability of using volumetric modulated arc therapy (RapidArc) on patients with brain metastasis to simultaneously treat the entire brain with focal areas of higher doses (boost) to grossly identified lesions on MRI scan to try to improve local control.

Several studies have indicated that patients at high risk of brain involvement, but without gross brain metastases, achieve high levels of intracranial control with lower "prophylactic disease" doses. The typical prophylactic cranial irradiation (PCI) dose for lung cancer is 25 Gy in 10 fractions. With RapidArc technology, the whole brain at risk could be given a reduced PCI dose, while the gross disease seen on MRI can be boosted with higher doses known to lead to better local control.

There will be a single group based on the "prophylactic" regimen for whole brain radiation. Dose escalation enrollment will be done sequentially within this group. For example, when the first dose level has completed accrual and is closed to new enrollment, all patients at that dose level will be monitored. After review all all patients, the investigators will make the decision whether or not to escalate to the next dose level. Patients will know which specific dose level they are assigned to.

After treatment that will take 10 days, patients will be followed closely for treatment outcome and possible side effects. Patients will be asked to complete three quick surveys at each follow-up appointment regarding quality of life and memory in addition to standard of care surveillance brain MRI and physical exam. The investigators hope to enroll between 12 and 24 patients at Emory University Hospital (EUH) and EUH Midtown.