• Biopsy-proven non-hematopoietic malignancy, except for small cell lung cancer, germ cell cancer, or unknown primary tumor.

• Radiographic evidence by MRI (or by CT scan with CT contrast if ineligible or intolerant of MRI) of brain metastasis. (If patient is unable to tolerate MRI contrast, an MRI without contrast is acceptable if lesions are visible)

• All brain metastases must be outside the brain stem (midbrain, pons and medulla).

• Patient must have 10 or less brain metastases.

• The maximum diameter of any lesion must be less than or equal to 3.0 cm.

• Previous treatment with surgery, radiation, chemotherapy, immunotherapy or any targeted agents are allowed provided that:

‣ Radiation was not to the brain.

⁃ Surgery to the brain was \> 7 days prior to SRS and there remains at least one additional brain metastasis that can be targeted with SRS

• Age ≥ 18 years.

• ECOG Performance Score of 2 or better/Karnofsky Performance Status score of 50-60 or better.

• All men, as well as women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.

• A female of child-bearing potential is any woman (regardless of sexual orientation, marital status, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:

⁃ Has not undergone a hysterectomy or bilateral oophorectomy; or

⁃ Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).

⁃ Ability to understand and the willingness to sign a written informed consent.