Gamma Knife radiosurgery is a well-established treatment method used to treat brain tumors and other conditions of the brain. The Mischer Neuroscience Institute at Memorial Hermann-Texas Medical Center has successfully treated more than 3,400 patients since acquiring the region's first Gamma Knife in 1993.

The Institute is now using the more advanced Leksell Gamma Knife Perfexion™. Patients who benefit from Perfexion’s sophisticated software with dose-to-target conformation include those with meningiomas and vestibular schwannomas; arteriovenous malformations; medically refractory trigeminal neuralgia; and metastases. Multiple intracranial metastases can usually be treated in a single outpatient procedure.

What is Gamma Knife Radiosurgery?

Gamma Knife brain surgery is a unique treatment method that delivers extremely focused radiation beams to targets in the brain. One hundred and ninety-two individual beams of radiation are positioned in a hemisphere so that all the beams can converge on a single focal point. The shape and dose of radiation is optimized to hit only the target, without damaging surrounding healthy tissue.

How Is Gamma Knife Different?

Leksell Gamma Knife does not involve incisions in your head. Instead, very precisely focused beams of radiation are directed to areas within the brain that require treatment, virtually eliminating potential surgical risks. The treatment procedure is simple, safe and effective.

Gamma Knife Treatment Steps

The treatment consists of four steps:

  1. Attaching the frame
  2. MRI, CT or angiography
  3. Treatment planning
  4. Treatment delivery

Before the Treatment

Our multidisciplinary treatment team consists of neurosurgeons, radiation oncologists, medical physicists and dedicated nursing staff. Candidates for Gamma Knife are assessed by our medical team prior to scheduling the procedure. Before treatment, a member of this team will educate you about the entire procedure.

The Head frame

A key component in Gamma Knife radiosurgery is the stereotactic head frame. The frame allows the doctor to accurately pinpoint the target to be treated in your brain. The lightweight frame is attached to your head with four pins and ensures that the radiation beams can be directed with precision to the target. The frame also prevents your head from moving during imaging and treatment.

Gamma Knife radiosurgery does not require cutting or shaving of your hair.

Sedation and analgesics are administered before the head frame is attached to reduce anxiety and discomfort. Each patient is monitored throughout the entire procedure and recovery by a nurse dedicated to their care.


After the head frame is in place, imaging such as MRI, CT or angiography is performed. Imaging is required to determine the exact size, shape and position of the target in the brain.

During imaging, a coordinate box is placed on the head frame to provide reference points on the images for the treatment plan. After imaging, the coordinate box is removed.

Treatment planning

No two treatment plans are alike; every patient's plan is individually designed to address their specific neurological condition. The neurosurgeon, radiation oncologist, physicist and neuroradiologist work together to develop a very precise and accurate treatment plan. This process may take up to an hour to complete.

The treatment

Once your plan is complete, your actual treatment will begin. You will lie down on the treatment couch and the head frame will be attached to the docking device. When the treatment begins, the couch will move into the dome section of the unit.

Silent and Painless. Gamma Knife radiosurgery is silent and painless. You are awake during the procedure and will be able to communicate with your doctor and nurse, who will be monitoring the procedure at all times through an audio and video connection. Feel free to bring in your own iPod or MP3 player, as you will be able to listen to music during the treatment.

Length of Treatment. The treatment will last a few minutes to more than an hour, depending on the size and shape of the target(s). Additional sedation and analgesics may be administered any time during your treatment to improve your level of comfort.

After the treatment

When your treatment is complete, the head frame will be removed. If you had an angiogram, you may have to rest in bed for a few more hours while you recover.

Most patients do not experience any problems after their treatment, although some patients may have a mild headache or minor swelling where the frame was attached. The majority of patients are discharged home on the same day of the procedure.


Radiation treatments are designed to work over time. This means that the effect of the treatment will be seen over a period of weeks or months. Your physician will stay in contact with you over time to assess your progress, which typically includes follow-up MRI, CT or angiography images.

Contact Us

Please fill out the fields below, and we will contact you.


Thank you for contacting Memorial Hermann. We have received your inquiry, and a team member will contact you soon.

If you need more immediate assistance, please call us at (713) 222-CARE.

If you are experiencing a medical emergency, call 911 or go to the nearest emergency room.