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Cranial Radiosurgery: Gamma Knife

Gamma Knife

Gamma Knife® or Stereotactic Radiosurgery (SRS)
Cranial Radiosurgery is a highly advanced technology that allows UAB specialists to treat Arteriovenous Malformations (AVMs), benign and malignant brain tumors, some vascular malformations, and other functional brain disorders without an incision and without damaging healthy tissue. This procedure offers patients a safe, effective alternative to conventional neurosurgery within the Leksell Gamma Knife unit located at UAB Highlands.

UAB is a pioneer in the field of cranial radiosurgery, performing its first treatment procedure in 1992. Since then, the program has successfully treated thousands of cases and remains one of the most experienced radiosurgical centers in the United States. For 40 years, the UAB Comprehensive Cancer Center has been recognized for its excellent care, innovative research, and expert specialists. The Cranial Radiosurgery Program is an integral part of the comprehensive care approach.

Please select any of the following links to learn more about the treatment procedure and technology involved with cranial radiosurgery.

What is Gamma Knife?
Gamma Knife is the trade name of the equipment that delivers radiosurgery treatment to the brain. Despite the terminology, a Gamma Knife is not a knife at all. Elekta’s Leksell Gamma Knife is actually a machine that delivers precise radiation beams to treat brain tumors, lesions or acoustic neuroma.

The instrument delivers 201 tightly focused cobalt radiation beams to a precise point in the brain. In fact, the radiation beams and dose are so precise that they affect only the targeted tissue and spare surrounding healthy tissue.

Because the procedure requires no incision, it is bloodless and carries few of the risks of traditional open surgery. Most patients are treated in one session and can return home soon after the procedure.

What can be expected before undergoing a Gamma Knife treatment?
As part of a multidisciplinary process, a radiation oncologist and neurosurgeon will determine if a lesion is suitable for Gamma Knife treatment. The type, size and location of the lesion may mean that open surgery is a better option for some patients.

Each patient meets with a specialist who will explain the procedure. The specialist belongs to a team of experts that conducts the surgery and provides care. The team usually consists of the radiation oncologist, the neurosurgeon and a medical physicist. As part of the UAB Health System, these specialists also have instant access to resources and expertise in more than 30 fields of medicine if the need should arise.

The patient is then fitted with a stereotactic head frame. The lightweight frame keeps the head still during the procedure and ensures that radiation hits the precise target in the brain. Local anesthetic is used where the frame fits to the head. The patient does not have to cut or shave his or her hair.

Imaging, such as magnetic resonance imaging (MRI), computed tomography (CT) or angiography, is done to determine the exact size, shape and position of the target in the brain. A coordinate box is placed on the head frame during imaging to provide reference points for images.

Next, the specialist team develops a treatment plan tailored to each patient’s specific needs and condition. The plan identifies the precise target in the brain for the radiation and calculates how the radiosurgery should be performed.

What can a patient expect during Gamma Knife treatment procedure?
Gamma Knife treatment itself is silent and painless. The patient is awake during treatment and is able to communicate with specialists and nurses through an audio/video connection. The patient lies on a couch, with the head frame attached to a metal helmet. When treatment begins, the couch moves into a dome that holds and aims the radiation. The actual treatment lasts from one to three hours, depending on the target’s size and shape. The specialist team monitors each patient constantly throughout the procedure. The patient should expect to be at the Gamma Knife facility the entire day.

What can a patient expect after their Gamma Knife treatment?
Once the radiosurgery is complete, some patients occasionally have a mild headache or minor swelling where the head frame was attached.

Most patients are able to return home immediately. Even if patients stay in the hospital overnight for observation, most can return to normal routines in a day or two.

The effects of radiation treatment occur over time, usually a period of weeks or months. Each patient’s physician will assess his or her progress, which may involve follow-up MRI, CT or angiography imaging.

What are the features and benefits of Gamma Knife?
As one of the most experienced radiosurgical centers, the UAB Radiosurgery Program strives to offer the best and most efficient treatment technology for cranial radiosurgery. Compared to other all-in-one systems, like the Accuray’s CyberKnife, the Leksell Gamma Knife sets the gold standard for the treatment of intracranial procedures, including benign and malignant brain lesions, vascular malformations and functional conditions. Its clinical effectiveness has been documented over nearly four decades, with more than 400,000 cases treated worldwide providing the data for 2,000+ publications in peer-reviewed medical literature.

Please review the following table to view features and advantages of Gamma Knife surgery.

Gamma Knife CyberKnife
201 source cobalt unit designed exclusively for non-invasive brain surgery Single source linear accelerator with robotic arm to compensate for patient movement during treatment; not exclusively used in intracranial SRS
Radiologic accuracy better than 0.3 mm 1 mm accuracy; dose outside the target area is 2x-6x greater than with Gamma Knife
Rigid immobilization to prevent head movement using a lightweight stereotactic head frame fixed to the outer skull. Provides exact MR and CT correlation from planning to treatment delivery in 3-D Non-rigid immobilization reduces head movement by using thermoplastic face mask that is shrink-wrapped to the table during treatment. Provides relative MR and CT correlation from planning to treatment delivery in 3-D. The CyberKnife is inherently less accurate since the positioning is optically guided, not head-frame based
Treatment delivered during one session Single or multiple treatments, possibly over a period of days
Target position is confirmed 10 times per second Target position confirmed once every 10 seconds

Last Update

June 2, 2010
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