Gamma Knife
Unlike CyberKnife, which mounts a linear accelerator on a robotic arm and can treat targets throughout the body, Gamma Knife is built specifically for the brain: many fixed cobalt-60 radiation sources are focused onto an intracranial target in a single session, typically using a rigid head frame or fitted mask for precision. It is used for conditions such as brain metastases, meningioma, and acoustic neuroma that are small and well-defined enough for focused radiation rather than open surgery.