Gamma Knife®

Gamma Knife® therapy is one of the most precise, powerful, and proven treatments for brain disorders. It is noninvasive, effective, and safe. This makes it an optimal choice for treating a wide variety of conditions, including benign or malignant brain tumors, blood vessel malformations, trigeminal neuralgia (also called tic douloureux), and tremor.

Gamma Knife is not an actual knife, and the therapy does not involve surgery. Instead, it focuses 201 precise beams of radiation directly on the tumor. Individually, the beams are too weak to damage healthy tissue, but when they converge, they deliver powerful treatment to a single point.

Another term for this type of noninvasive neurosurgery is stereotactic radiosurgery. This refers to directing radiation to a specific focal point using an external, three-dimensional frame of reference—such as the head frame used in Gamma Knife radiosurgery.

To establish the target for the radiation, Penn Medicine’s physicians create detailed maps of the brain using magnetic resonance imaging (MRI), computed tomography (CT), or angiography. They then determine the precise amount of radiation needed to treat the cancer.

There are many benefits to Gamma Knife radiosurgery. In most cases, only a single procedure is necessary, and you can quickly return to your normal routine afterward. Gamma Knife eliminates the need for lengthy hospitalization, medications, and rehabilitation.

Our experienced Gamma Knife team provides patients with maximum safety and efficacy. Skilled pre-treatment planning and the radiation's focused delivery method lead to improved outcomes, enhanced quality of life, and virtually no damage to healthy brain tissue.

Your physician and our Gamma Knife team members will discuss the radiosurgery with you before the procedure takes place. Since Gamma Knife radiosurgery is noninvasive, it is not necessary to shave or cut your hair.

During surgery

Gamma Knife radiosurgery planning and treatment are performed on the same day. Treatment includes three phases: fitting the head frame, procedure planning, and the procedure.

Fitting the head frame

One of the key components in Gamma Knife radiosurgery is what is called the stereotactic head frame. The frame allows the physician to accurately pinpoint the area within your brain that will be treated. The frame is lightweight and attaches to the head with four screws, which ensures that the radiation beams are precisely directed to the target. In addition, the frame prevents the head from moving during imaging and treatment. A local anesthetic will be applied where the screws are to be attached.

Once the head frame is in place, images will be taken of your brain. This imaging may include MRI scans, CT scans, or angiography. Imaging will determine the exact size, shape, and position of the target within your brain.

Radiosurgical planning

The next stage is radiosurgical planning. Once the images have been taken, you are allowed to rest while the Gamma Knife physicians develop a precise radiosurgical plan. The plan is made using a specially designed computer that helps calculate how the radiosurgical procedure should be performed. This generally takes one to two hours. During this time, you can rest, watch television, read, and use the restroom. The stereotactic head frame will remain attached.

The radiosurgical procedure

Once the radiosurgical plan is completed, the actual radiosurgical procedure can begin. You will lie down on the procedure couch, and the head frame will be attached to a helmet. You will be awake throughout and will be able to communicate with the Gamma Knife team through an audio and video connection. We will monitor you at all times. The procedure is silent and painless.

The radiosurgery lasts a few minutes to more than an hour, depending on the size and shape of the targeted area.

Most patients should be able to return to their normal routines within a day or so. Some patients may be required to lie quietly for several hours after treatment or stay overnight for observation.

Follow-up is key when you’ve had Gamma Knife radiosurgery. That is because the effects of radiosurgery occur over a period of weeks or months. Treatment is designed to stop the growth of tumors or lesions over a period of time. It is important that you stay in contact with your physician to determine progress of your treatment. This may involve follow-up imaging such as MRI, CT, or angiography.

Some patients may experience a mild headache or minor swelling where the head frame was attached. Your doctor will discuss any potential side effects. 

At Penn Medicine, Gamma Knife is a highly developed treatment for brain tumors, skull base tumors, and other brain disorders. Like other forms of radiation therapy, Gamma Knife damages the cancer cells and prevents them from multiplying. After treatment, the tumor stops growing and, in many cases, it disappears over time.

Expertise you can count on

Our providers have decades of experience performing stereotactic radiation treatment and are skilled at Gamma Knife therapy. Some of the advantages of this therapy include:

• Precision: The customized dose of radiation targets only the diseased tissue, leaving the surrounding healthy tissue intact.
• Safety: Patients generally require only local anesthesia and mild sedation. There are no incisions and no risk of infection, bleeding, and other possible complications that come with cutting into the skull and exposing the brain.
• Effectiveness: Gamma Knife is especially effective for cancer that has spread from other areas of the body, often with only one treatment needed. The therapy offers new hope to patients with deep-seated brain lesions or skull base tumors once considered inoperable.
• Technologically advanced: The Gamma Knife is robotically controlled, allowing surgeons to deliver radiation more precisely, safely, and faster than ever before.