Stereotactic Radiosurgery

What is stereotactic radiosurgery and how is it used?
Stereotactic radiosurgery is a highly precise form of radiation therapy used primarily to treat tumors and other abnormalities of the brain. Despite its name, stereotactic radiosurgery is a non-surgical procedure that uses highly focused x-rays to treat certain types of tumors, inoperable lesions and as a post-operative treatment to eliminate any leftover tumor tissue.

The treatment involves the delivery of a single high-dose of radiation beams that converge on the specific area of the brain where the tumor or other abnormality resides. Using a helmet-like device that keeps the head completely still and three-dimensional computer-aided planning software, stereotactic radiosurgery minimizes the amount of radiation to healthy brain tissue.

Stereotactic radiosurgery is an important alternative to invasive surgery, especially for tumors and blood vessel abnormalities located deep within or close to vital areas of the brain. Radiosurgery is used to treat many types of brain tumors, both benign or malignant and primary or metastatic. Additionally, radiosurgery is used to treat arteriovenous malformations (AVMs), a tangle of expanded blood vessels that disrupts normal blood flow in the brain and is the leading cause of stroke in young people.

Although stereotactic radiosurgery is often completed in a one-day session, physicians sometimes recommend a fractionated treatment, in which treatments are given over a period of days or weeks. This is referred to as stereotactic radiotherapy.

Stereotactic radiosurgery works in the same way as other forms of radiation treatment. It does not actually remove the tumor; rather, it distorts the DNA of tumor cells. As a result, these cells lose their ability to reproduce. Following the treatment, benign tumors usually shrink over a period of 18 months to two years. Malignant and metastatic tumors may shrink more rapidly, even within a couple of months. When treated with radiosurgery, arteriovenous malformations (AVMs) begin to thicken and close off.

How is the procedure performed?
Radiosurgery involves four phases: placement of the head frame, imaging of tumor location, computerized dose planning, and radiation delivery.

In the first phase, a box-shaped head frame is attached to your skull using specially designed pins to keep your head from moving until the treatment session is finished. This lightweight aluminum head frame is a guiding device that makes sure the beams are focused exactly where the treatment is needed.

Next, you will be taken to an imaging area where a computed tomography (CT) scan and/or magnetic resonance imaging (MRI) will be performed to show the exact location of the tumor in relation to the head frame.

During the next phase, you will be able to relax for an hour or two while your treatment team performs a computer-aided treatment plan that will optimally radiate the tumor.

Next, you will lie down on the couch where your physician will describe the number and length of treatments to expect. Your head frame will then be attached to special stand that will allow individual rays of radiation to target specific areas of the brain.

The treatment team will then go to another room so that your treatment can begin. You will be able to talk to your physician and a camera will allow the team to see you at all times. The machine will move around you. When the treatment is complete, your therapist will remove the attachment from your head. This is a painless process.

What will I feel during this procedure?
A nurse will place a small needle in your hand or arm to give medications, if needed, and a contrast material. Before the neurosurgeon positions and attaches your head frame, you will be injected with a local anesthetic in the front and back of your head to numb your scalp. These shots are only slightly uncomfortable and will help to minimize the discomfort of the head frame. As the head frame is pinned to your skull, you will feel pressure or tightness that typically disappears within 15 minutes.

Radiosurgery treatments are similar to having an x-ray. You will not be able to see, feel or hear the x-rays. There is no pain or discomfort from the actual treatment. If you experience pain for other reasons, such as back pain or discomfort from the head frame, you should let your doctor or nurse know.

When the head frame is removed, there may be some minor bleeding from the pin sites that will be bandaged. You may experience nausea and/or a headache and can ask for medication to help make you feel more comfortable.