Stereotactic radiosurgery


Stereotactic radiosurgery is a form of radiation therapy that focuses high-powered x-rays on a small area of the body.

With regular radiation therapy treatment, the healthy tissue nearby also receives radiation.

Stereotactic radiosurgery better focuses the radiation on the abnormal area.

Despite its name, radiosurgery is a form of radiation therapy, not a surgical procedure.

Alternative Names

Gamma knife; Cyberknife; Stereotactic radiotherapy (SRT); Stereotactic body radiotherapy (SBRT); Fractionated stereotactic radiotherapy; Cyclotrons; Linear accelerator; Linacs; Proton beam radiosurgery


During treatment, you will lie on a table, which slides into a machine that delivers radiation beams. The machine may rotate around you while it works.

Sometimes, a head frame may be attached to your scalp to keep you very still during therapy. There are many different machines used to perform stereotactic radiosurgery. Some machines require the use of a frame.

  • You may need small pins or anchors that go through your skin, but not into your skull or bone.
  • If this is done the area will be cleaned, your skin will be numbed and you may be given medicine to help you relax. You will be awake and able to talk.

At other times, a special plastic mask that is fitted for your face may be used.

An MRI, MR angiography, or CT scan is then done to help plan the procedure. You will wait while your doctor reviews the results and plans your treatment. Sometimes, the scans are scheduled a few days in advance.

During the actual treatment, you will be alone in the room. The nurses and doctors will be able to see you on cameras, and hear you and talk with you on microphones.

The radiation usually takes only about 30 minutes to 1 hour. Some patients may receive more than one treatment session, but usually no more than five sessions.

Why the Procedure Is Performed

Stereotactic radiosurgery is often used to slow down the growth of small, deep brain tumors that are hard to remove during surgery. Such therapy may also be used in patients who are unable to have surgery, such as the elderly or those who are very sick. Radiosurgery may also be used after surgery to treat any remaining abnormal tissue.

Stereotactic radiosurgery was once limited to brain tumors, but today it may be used to treat many other diseases and conditions.

Brain and nervous system tumors:

Other conditions:

Other cancers for which radiosurgery is either being used or studied include:


Radiosurgery may damage tissue around the area being treated. Brain swelling may occur in people who received treatment to the brain. Swelling usually goes away, but some people may need medicine to control long-term swelling.

Before the Procedure

Before the treatment, you will have MRI or CT scans. Using these images, a computer creates a 3-D (three dimensional) map of the tumor area. This planning process helps your neurosurgeon and radiation oncologist determine the specific treatment area.

The day before your procedure:

  • Do not use any hair creams or hair spray.
  • Do not eat or drink anything after midnight unless told otherwise by your doctor.

The day of your procedure:

  • Wear comfortable clothing.
  • Bring your regular prescription medicines with you to the hospital.
  • Do not wear jewelry, makeup, nail polish, or a wig or hairpiece.
  • You will be asked to remove contact lenses, eyeglasses, and dentures.
  • You will change into a hospital gown.
  • An intravenous (lV) line will be placed into your arm to deliver contrast material, medicines, and fluids.

After the Procedure

Often, you will be able to go home about an hour after the treatment is finished. You should arrange for someone to drive you home. Most people go back to their regular activities the next day, if there are no complications such as swelling. Some patients are kept in the hospital overnight for monitoring.

Outlook (Prognosis)

The effects of radiosurgery may take weeks or months to be seen. The prognosis depends on the condition being treated. Many times, your health care provider will monitor your progress using imaging tests such as MRI and CT scans.


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Barbaro NM, Quigg M, Broshek DK, Ward MM, Lamborn KR, Laxer KD, et al. A multicenter prospective pilot study of gamma knife radiosurgery for mesial temporal lobe epilepsy: seizure response, adverse events, and verbal memory. Ann Neurol. 2009;65:167-175.

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Linskey ME, Andrews DW, Asher AL, Burri SH, Kondziolka D, Robinson PD, et al. The role of stereotactic radiosurgery in the management of patients with newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline. J Neurooncol. 2010;96:45-68. Epub 2009 Dec. 4.

Review Date: 6/15/2010
Reviewed By: David Herold, MD, Radiation Oncologist in West Palm Beach, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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