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By Mayo Clinic staff
Gamma-knife surgery 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 is done with computerized tomography (CT), a specialized X-ray that creates cross-sectional images of the brain, or magnetic resonance imaging (MRI), which uses a magnetic field and radio waves to create cross-sectional or 3-D images of the brain. In some cases, both imaging methods are used. You may receive an injection of a special dye (contrast agent) that enhances the brain tumor image.
- AVMs. Imaging for brain AVMs may include CT scans, MRI scans, cerebral angiograms, or some combination of these tests. A cerebral angiogram is an X-ray with a contrast agent. A small tube (catheter) is inserted into a blood vessel in your groin and threaded to the brain to deliver the contrast agent. A contrast agent for CT or MRI scans of AVMs is usually injected into a vein.
- Trigeminal neuralgia. MRI 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 dosages of radiation and the configuration of radiation beams. 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 typically 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 duration of the treatment can range from 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 a headache, nausea or vomiting right after the procedure, you'll receive appropriate medications.
- You'll be able to eat and drink after the procedure.
- Stereotactic radiosurgery overview. International RadioSurgery Association. http://www.irsa.org/radiosurgery.html. Accessed Aug. 3, 2010.
- Gamma Knife® surgery. International RadioSurgery Association. http://www.irsa.org/gamma_knife.html. Accessed Aug. 3, 2010.
- Stereotactic radiosurgery. American Association of Neurological Surgeons. http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Stereotactic%20Radiosurgery.aspx. Accessed Aug. 3, 2010.
- Gamma Knife®. Radiological Society of North America. http://www.radiologyinfo.org/en/info.cfm?pg=gamma_knife. Accessed Aug. 3, 2010.
- Stereotactic radiosurgery and stereotactic body radiotherapy (SBRT). Radiological Society of North America. http://www.radiologyinfo.org/en/info.cfm?PG=stereotactic. Accessed Aug. 3, 2010.
- Brain tumors. American Association of Neurological Surgeons. http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Brain%20Tumors.aspx. Accessed Aug. 3, 2010.
- Arteriovenous malformations. American Association of Neurological Surgeons. http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Arteriovenous%20Malformations.aspx. Accessed Aug. 3, 2010.
- Trigeminal neuralgia fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/trigeminal_neuralgia/detail_trigeminal_neuralgia.htm. Accessed Aug. 3, 2010.
- Vestibular schwannoma (acoustic neuroma) and neurofibromatosis. National Institute on Deafness and Other Communication Disorders. http://www.nidcd.nih.gov/health/hearing/acoustic_neuroma.html. Accessed Aug. 4, 2010.
- NINDS pituitary tumors information page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/pituitary_tumors/pituitary_tumors.htm. Accessed Aug. 4, 2010.
- Kavanagh G, et al. Complications of cranial stereotactic radiosurgery. http://www.uptodate.com/home/index.html. Accessed Aug. 4, 2010.
- A typical treatment day. International RadioSurgery Association. http://www.irsa.org/treatment.html. Accessed Aug. 3, 2010.
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