The Gamma Knife is an advanced radiation treatment for conditions such as small to medium size tumors, epilepsy and abnormal blood vessel formations located deep in the brain called arteriovenous malformations. Despite its name, this treatment doesn't involve a knife but delivers a single, precisely targeted, high dose of radiation, while causing little or no damage to surrounding tissue.

Gamma Knife treatment consists of six basic steps: preparation, applying the frame, imaging, treatment planning, treatment and recovery.

You and your child will visit the hospital one to two days before the Gamma Knife procedure for blood tests and to meet with the doctors who will perform the procedure. A schedule of appointments will be sent to you by mail from the UCSF Gamma Knife Radiosurgery Program. Please let us know if your child has had any of the required tests performed in the past year. If so, please bring copies of the test results with you.

You will meet with a neurosurgeon and a radiation oncologist who will record your child's medical history, perform a physical examination and obtain your consent to perform the Gamma Knife procedure. You will have an opportunity to tour the Gamma Knife treatment room and ask questions about the procedure and expected results. We recommend that you write down as many questions as possible before your appointment to ensure you don't forget them.

Night Before Treatment

If you live outside of the San Francisco area, please stay in a hotel or guesthouse near UCSF Medical Center. Your child should not eat after 2 a.m. He or she should take all regular medications the day before and the morning of the procedure with a small amount of water.

Morning of Treatment

Typically, your child will be in the hospital only for the day of the procedure. Bring your child's medications so he or she can take them during the day, as needed. Slipper-socks and robes are provided. Please bring reading materials, audio CDs or DVDs to watch in the patient waiting area. Remember to leave any valuables your child may have, such as jewelry or cash, at home.

Please arrive at the hospital at 505 Parnassus Ave. between 6 and 6:30 a.m. Go to the Outpatient Surgical Waiting Area in room M-104J. The room is located on the first floor to the right of the lobby. An escort will meet you there. The phone number for the waiting area is (415) 353-1626.

An escort will take you and your child to the fourth floor pre-operative area. (You, a family member or friend may accompany your child.) Your child will be asked to put on a hospital gown and a nurse will start an intravenous (IV) line to administer fluids and a mild sedative during the procedure. The same IV is used to administer the contrast agent for your imaging studies. Please remove eyeglasses and other personal belongings.

Applying the Frame

A stereotactic frame, placed on your child's head, will act as a guide to find the exact location of the brain lesion or tumor. Your child's head will not be shaved.

Children are given general anesthesia before the frame is attached and remain asleep during the procedure. A neuro-anesthesiologist gives the anesthesia and stays with your child throughout the procedure.

Imaging Studies

Before the procedure, your child will undergo imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans or a cerebral angiogram. These studies help doctors locate the brain lesion as it relates to the stereotactic frame.

Treatment Planning

After imaging studies are performed, your child's treatment will be planned.

Treatment planning could take one to several hours depending on the size and shape of the target area. Your child's doctors will locate the brain lesion or tumor and its dimensions using computer software and data from the imaging studies. The position of your child's head during treatment, radiation dose and length of treatment will be determined.


After doctors plan the treatment, your child will be brought to the Gamma Knife area and placed on a treatment bed, lying on his or her back. Your child's blood pressure and pulse will be monitored throughout the treatment. The stereotactic frame will be fitted into a steel helmet and fixed in position. Doctors will leave the room when treatment is ready to begin and will observe your child on video camera.

When treatment starts, the treatment bed will move into a large shielded sphere. Only your child's head will be inside the sphere. The steel helmet will interlock with another helmet inside the sphere that holds the source of radiation.

During treatment, your child will remain asleep. Each "shot" of radiation will last one to several minutes. At the end of each shot, the steel helmet unlocks from the inner helmet and the treatment bed moves out of the sphere. For most patients, the automatic patient positioning system moves your child to the next position. In some cases, it is necessary for doctors to manually position your child in the helmet for each shot. The entire treatment may consist of one or several shots of radiation.


After treatment, the stereotactic frame is removed and your child will be transferred to a recovery room where he or she will be monitored and you can stay until discharge. Your child may have a headache. Not having eaten all day may add to the discomfort. Medication for a headache will be provided as needed. Most children return home at the end of the day and may resume normal activities, including eating and drinking, as he or she is able.

Follow-up instructions will be provided before you leave the hospital. If you need more medication, you will receive a prescription.

If you have any concerns or questions after the procedure, please call the Gamma Knife nurse at (415) 353-9325.