This study compares two types of radiation therapy for brain tumor patients after surgery. The first type is GammaTile therapy, which involves placing a small radiation device directly where the tumor was removed. The second type is traditional SRT (Stereotactic Radiotherapy), done 3-4 weeks after surgery. This study aims to see which method is more effective and safe.

• The study involves random selection for treatment and requires regular follow-ups.
• Participants must be 18 or older with 1-6 brain metastases, among other health requirements.
• GammaTile therapy is FDA-approved and might reduce the risk of radiation necrosis.

Eligible patients will have brain tumors between 2.0 and 7.0 cm removed and treated with one of the radiation therapies. Non-surgical tumors will also receive radiation treatment. Participants must be able to understand the study's requirements and provide consent. The study aims to provide more data on GammaTile's effectiveness and safety compared to the standard SRT.