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Gamma Knife Radiosurgery

  • A treatment using high-dose radiation to target brain tumors
  • For people with brain metastases
  • There is little recovery time involved—some may experience fatigue and/or headaches
  • Involves Neurosurgery and Therapeutic Radiology

Gamma Knife Radiosurgery


Brain surgery once meant using a knife and opening the skull, and “radiation” was a treatment that sacrificed normal brain cells for the sake of killing cancerous ones.

But Gamma Knife radiosurgery is a noninvasive treatment for brain tumors that allows physicians to preserve most of the patient’s healthy brain tissue. This game-changing procedure has been especially effective in helping to reduce the size of metastatic tumors—tumors that develop in the brain due to cancer that has spread from another part of the body.

“When we first started doing radiosurgery more than a decade ago, patients with metastatic brain tumors were only living six to eight months, on average,” says Veronica Chiang, MD, director of Central Nervous System Radiotherapy and the Gamma Knife Center at Yale Medicine. “Now we’re talking about survival rates in the order of years. To give these patients their best outcome and quality of life, we as physicians must work together in a coordinated fashion to make sure that we use the right treatment at the right time. The use of Gamma Knife has revolutionized our ability to keep patients well neurologically while they maximally benefit from their cancer treatments.”   

What is Gamma Knife radiosurgery?

Radiosurgery is a technique that combines the precision of brain surgery with the effectiveness of high-dose radiation. It creates a noninvasive treatment for brain tumors that allows physicians to preserve most of the patient’s healthy brain tissue. This procedure has been used for decades to treat functional disorders such as tremors related to Parkinson’s disease, as well as benign brain lesions such as meningiomas, pituitary adenomas, and arteriovenous malformations.

In the past decade, however, the use of radiosurgery has become much more commonplace because of its newly recognized benefit in the treatment of metastatic brain tumors. These tumors develop in the brain due to cancer having spread from other parts of the body.

What are the benefits of Gamma Knife radiosurgery?

Gamma Knife radiosurgery is noninvasive and can often be a safer alternative to open brain surgery.

Because the radiation used in Gamma Knife therapies is targeted precisely to the areas in the brain where a tumor is situated, it can be a better alternative than traditional radiation therapy. Compared with large field radiation, you will not lose all your hair or experience the loss of cognitive functions that can accompany radiation to the entire head.

Gamma Knife treatment is also more efficient than other radiosurgery treatments. Typically with the cyberknife and other LINAC-based machines, imaging and treatment are often separated by at least one or two weeks—sometimes up to a month. This difference could mean that any changes that occur in the brain in those weeks will not be accounted for at the time of treatment. 

Gamma Knife radiosurgery includes both imaging and treatment on the same day, so the treatment plan is up-to-date and also minimizes any delay to the treatment of the body. In patients taking oral medicines for treatment, only one or two days of treatment, at most, need to be skipped for Gamma Knife treatment. 

Who is a candidate for Gamma Knife radiosurgery?

Because Gamma Knife therapy relies on the ability to identify the treatment target through imaging, patients whose lesions are easily identifiable using computerized tomography (CT) or magnetic resistance imaging (MRI) often make the best candidates.

While many conditions only have a single target, the Gamma Knife machine used at Yale Medicine was designed specifically to treat multiple lesions. For patients with brain metastases, for example, the treatment of 15 to 20 tumors in a single day is no longer uncommon.

How does Gamma Knife surgery work?

Gamma Knife surgery is an outpatient procedure that typically lasts at least four or five hours, depending on the condition. 

When you arrive at the hospital, you may be given a light sedative to help ease the anxiety associated with application of a head frame used to identify the treatment target. After local anesthetic is administered to two points around the head, the frame is attached firmly to the skull.

With the frame in place, imaging tools such as an MRI and/or CT scans identify the precise locations of the tumors in relationship to the attached frame. During the next few hours, the radiosurgery team will then create an individualized radiation treatment plan for each identified lesion. During this waiting time, you will be able to eat or drink—and rest.

When the radiation plan is ready, you will be positioned on your back, on a bed, with your head inside the Gamma Knife machine. The frame will hold your head perfectly still and help guide the delivery of the radiation. The treatment can take up to several hours. During this time, you will not be able to feel, hear, or otherwise detect the radiation you are receiving. 

Once the treatment is completed, you will be taken out of the Gamma Knife machine, the head frame will be removed and a small dressing will be wrapped around your head to cover the frame attachment sites. You can go home right after the procedure.

What is recovery from Gamma Knife radiosurgery like?

Many patients are surprised by how quickly they are back on their feet after the Gamma Knife procedure.

“People walk out pretty much the way they came in, except they’ll have a head bandage on,” says Dr. Chiang.  “Many people go back to work the following day.”

Side effects after Gamma Knife are rare and typically minor.

You may experience fatigue, related to the length of the procedure, and headaches related to the head frame. And while Gamma Knife therapy will not cause significant hair loss, the scalp can remain numb in some areas for a few weeks after the procedure.

What makes Yale Medicine’s approach to Gamma Knife radiosurgery unique?

Currently, Yale Medicine’s Smilow Cancer Hospital is the only radiation center in Connecticut that has a radiosurgery machine dedicated to treating head and neck lesions.

Yale Medicine is the destination for people across the Northeast who want to benefit from this highly accurate, noninvasive treatment.