Gamma Knife Radiosurgery uses Gamma Rays to treat brain tumours and other brain abnormalities without the need for invasive surgery. A stereotactic frame is fixed to your head, and an MRI Scan and a Cerebral Angiogram (X-Ray to view blood vessels in the brain) are performed before the surgery. These scans allow your surgeon to determine the dose of radiation needed to treat the diseased brain tissues, while protecting the surrounding normal tissue from radiation damage. You will then be positioned in the gamma knife machine and focused beams of radiation will be concentrated onto the diseased brain tissues. Gamma Knife Surgery is a non-invasive procedure. It is very safe and precise, and is usually performed as an outpatient procedure.