Stereotactic Radiosurgery

Linac Treatment at Mayo Clinic

Example of a treatment planning diagram.

Linac treatment is a form of stereotactic radiosurgery that uses a linear accelerator (linac) to deliver highly focused radiation with extreme accuracy to the brain and other areas of the body. The treatment is used to treat lesions and tumors smaller than four centimeters in diameter.

Linac treatment is offered at Mayo Clinic in Arizona and Jacksonville.

Linac treatment is so accurate that it can be safely aimed within a pinpoint of vital brain tissue. This precision allows physicians to treat small tumors and other problems deep in the brain or close to critical areas with limited risk. Radiosurgery also is used to treat non-cancerous, noninvasive tumors such as pituitary adenomas and acoustic neuromas, as well as arteriovenous malformations.

The type, location and size of the tumor help the radiosurgical team determine whether linac treatment is most appropriate. Some patients are treated in one day, while others receive multiple treatments (called fractionated stereotactic radiotherapy or radiosurgery).

What to Expect During Linac Treatment

Before treatment
A patient undergoing linac treatment arrives early on the morning of the procedure accompanied by the person who will drive them home. Similar to most surgical procedures, patients wear a hospital gown and are asked to remove jewelry, eyeglasses, contact lenses, dentures, wigs or hairpieces. A mild, intravenous (IV) sedative is given.

Headframe application
The patient is fitted for a lightweight head frame that will hold the head still during the procedure. First, a local anesthetic numbs the skin in the four places where the frame will attach to the head with mounting pins. The patient may feel slight pressure when the pins are inserted, but this usually goes away once the headframe is in place. Headframe application takes about 20 minutes.

Pinpointing the target
After a brief recovery time, the patient has a computed tomography (CT) scan so that the neurosurgeon can pinpoint the target for the linac treatment.

After the CT scan, patients are taken to a room to wait while their treatment is planned by a radiation oncologist, physicist and neurosurgeon. Treatment planning is detailed and can take several hours. During this time, patients may eat, watch television, listen to music, read, play cards and do other activities.

Treatment
When the treatment plan is complete, the patient is ready to begin linac treatment. First, the patient lies on a table where the headframe is secured to ensure that the patient's head does not move during the procedure. Several measurements are taken to ensure accuracy, and adjustments are made as needed. The measurements and the patient's head position are verified by the radiation oncologist and physicist, and then the treatment begins.

The linear accelerator rotates closely around the head several times during treatment, delivering focused radiation to the area(s) mapped out by the treatment team.

After treatment
The headframe is removed and antibiotic ointment is applied to the pin insertion sites. Follow-up exams are determined based on each patient's need. Typically, patients see the radiation oncologist and the neurosurgeon six to 12 weeks after treatment.