What Is the Gamma Knife?

The Gamma Knife is an instrument that delivers 201 extremely focused cobalt radiation beams to one point in the brain. The radiation is focused so precisely that it affects only the targeted tissue while sparing the 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 Is This Equipment Used For ?

The gamma knife and its associated computerized treatment planning software enable physicians to locate and irradiate relatively small targets in the head (mostly inside the brain) with extremely high precision. Intense doses of radiation can be given to the targeted area(s) while largely sparing the surrounding tissues. The gamma knife can be used for a wide variety of problems. For example, it can be used to treat selected malignant tumors that arise in or spread to the brain (primary brain tumors or metastatic tumors), benign brain tumors (meningiomas, pituitary adenomas, acoustic neuromas), blood vessel defects (arteriovenous malformations) and functional problems (trigeminal neuralgia). Possible future uses are being evaluated for epilepsy and Parkinson’s disease.

A multidisciplinary team approach provides patients with the greatest safety. The team is most commonly comprised of a radiation oncologist, a medical radiation physicist and a neurosurgeon—all specially trained in the use of the gamma knife—with support from nursing staff, anesthesiologists (for patients who are unable to cooperate, such as children) and radiation therapists, who work together to provide patients with the high-quality care they deserve.

Conditions for which the Gamma Knife® is considered most effective are:

1. Intracranial tumors such as acoustic neuromas, pituitary adenomas, pinealomas, craniopharyngiomas, meningiomas, chordomas, chondrosarcomas, metastases and glial tumors.
2. Vascular malformations including arteriovenous malformations.
3. Functional disorders such as trigeminal neuralgia and obsessive-compulsive disorder.

Evidence-based research has shown Gamma Knife® to be effective for trigeminal neuralgia. Research has not supported linear accelerator (linac) treatment of trigeminal neuralgia and other functional brain disorders like tremors and pain at this time. In addition to the above mentioned indications, functional disorders such as intractable pain, Parkinson’s disease, essential tremors and epilepsy are often treated with Gamma Knife®.

• Gamma Knife® is a neurosurgical tool designed exclusively for the treatment of brain disorders.
• The lesion being treated receives a high dose of radiation with minimum risk to nearby tissue and structures.
• The cost of a Gamma Knife® procedure is often 25% to 30% less than traditional neurosurgery.
• Patients experience little discomfort.
• The absence of an incision eliminates the risk of hemorrhage and infection.
• Hospitalization is short, typically an overnight stay or an outpatient surgical procedure. Patients can immediately resume their previous activities.
• Gamma Knife® technology allows treatment of inoperable lesions. The procedure offers hope to patients who were formerly considered untreatable or at very high risk during open skull surgery.

How the Procedure Works ?

When patients first come to the University of Maryland Medical Center for treatment, they must meet with the Gamma Knife medical team. The team is made up of three dedicated neurosurgeons and a radiation oncologist. The team then collaborates and decides on the best way to treat the patient’s condition.

On the day of the surgery, patients are fitted with a clear, plastic frame. This frame sits over their heads and helps team members to measure the distance the radiation beams must travel. The team then uses three-dimensional, computerized technology to figure out exactly where to administer the radiation.

Once this has been determined, patients are placed into the Gamma Knife apparatus. The Gamma Knife is a metal, helmet-like device that emits the radiation beams.

According to the medical team, the entire procedure, from the time the patient first arrives at the Gamma Knife Center to the completion of the treatments, only takes about four or five hours. Patients typically spend one night in the hospital and then go home.