What you can expect

By Mayo Clinic Staff

Gamma Knife radiosurgery is usually an outpatient procedure, but the entire process will take most of a day. You may be advised to have a family member or friend who can be with you during the day and who can take you home. In some cases, an overnight stay in the hospital may be necessary.

You'll have an intravenous (IV) line, a tube that delivers fluids to your bloodstream to keep you hydrated during the day. A needle at the end of the IV is placed in a vein, most likely in your arm.

Before the procedure

Before the procedure begins, you'll have a lightweight frame attached to your head with four pins. This frame will stabilize your head during the radiation treatment and serve as a point of reference for focusing the beams of radiation. During this process:

  • None of your hair will be shaved
  • You'll receive numbing shots in the four places on your scalp where the pins will be inserted — two points on your forehead and two at the back of your head

After the head frame is attached, you'll undergo imaging scans of your brain that show the location of the tumor or other abnormality in relation to the head frame. The type of scan used depends on the condition being treated:

  • Tumors. Imaging for tumors may include computerized tomography (CT scan) or magnetic resonance imaging (MRI). In a CT scan, a series of X-rays create a detailed image of your brain. In an MRI scan, a magnetic field and radio waves create detailed images of your brain.

    Doctors may inject a dye into a blood vessel to view the blood vessels in your brain and highlight blood circulation. In some cases, you may have an MRI and CT scan.

  • Arteriovenous malformations (AVMs). Imaging for brain AVMs may include CT scans, MRI scans, cerebral angiograms or some combination of these tests.

    In a cerebral angiogram, a doctor inserts a small tube in a blood vessel in your groin and threads it to the brain using X-ray imaging. A doctor injects dye through the blood vessels to make them visible on X-rays. Your doctor may inject a dye into a blood vessel during CT or MRI scans to view the blood vessels and highlight blood circulation.

  • Trigeminal neuralgia. An MRI or CT scan is used to create images of nerve fibers to select a target area for treating trigeminal neuralgia.

The results of the brain scans are fed into a computerized planning system that enables the radiosurgery team to plan the appropriate areas to treat, dosages of radiation and how to focus the radiation beams to treat the areas. This planning process may take an hour or two. During that time, you can relax in another room, but the frame must remain attached to your head.

Children are often anesthetized for the imaging tests and during the radiosurgery. Adults are usually awake, but you may be given a mild sedative to help you relax.

During the procedure

You'll lie on a bed that slides into the Gamma Knife machine, and your head frame will be attached securely to a helmet inside the machine. The procedure may take less than an hour to about four hours, depending on the size and shape of the target. During the procedure:

  • You won't feel the radiation.
  • You won't hear any noise from the machine.
  • You'll be able to talk with the doctors via a microphone.

After the procedure

After the procedure, you can expect the following:

  • The head frame will be removed.
  • You may have minor bleeding or tenderness at the pin sites.
  • If you experience headache, nausea or vomiting after the procedure, you'll receive appropriate medications.
  • You'll be able to eat and drink after the procedure.
May. 23, 2013