Treatment Procedure
On the morning of the procedure, the patient comes to the hospital and is fitted with a stereotactic frame. This device is a mechanical guiding instrument that provides reference numbers in the imaging studies that follow. Adults receive local anesthesia while the frame is being secured; children receive general anesthesia. The frame positions the head within the collimator helmet during the actual treatment.

Subsequently, imaging studies such as magnetic resonance imaging, computed tomography, angiography, and magnetic resonance angiography allow the physicians to precisely localize the tumor or vascular malformation. Using three-dimensional computerized dosimetry, the Gamma Knife team develops an individualized radiation dose plan for the patient.

The patient is then positioned on the Gamma Knife couch and the frame is attached to the helmet in a predetermined position. The helmet contains 201 portals, many or all through which the cobalt-60 beams are directed onto the target lesion. Once the patient is positioned and aligned, the bed moves into the shielded sphere containing the radiation sources.

A predetermined dose is administered via remote control and is repeated, as necessary, until coverage of the lesion is complete. The treatment team monitors the patient by video camera from an adjacent room and communicates with the patient through a two-way intercom. Patients typically experience minimal pain or discomfort during the treatment. The treatment itself is painless.