Note: At present the majority of stereotactic radiosurgery procedures to the brain are performed on the dedicated neurological instrument the Gamma Knife®. Therefore, the Gamma Knife treatment day is outlined here. Use of other technology will be similar but vary in small ways. Stereotactic radiosurgery is a one-session treatment. Radiation therapy is a treatment which occurs over time in multiple sessions.
You may be given a special shampoo to use. Having a clean scalp helps the staff to position the head frame better. You will be asked to remove all jewelry before treatment; therefore it is better not to bring it with you. In most cases you will be asked not to drink or eat from midnight on the night before your treatment until after your treatment. This will decrease the likelihood of having an upset stomach during the procedure. Bring with you to the treatment center all medications that you are taking. Ask the nurse or physician what to do about taking your normal medications on the day of treatment.
You will need to have someone from your family or a support person(s) accompany you, and stay in the Gamma Knife facility during treatment, just the same as if you were having surgery. In most facilities they will be allowed to stay with you for much of the time before treatment. This person should be able to drive you home, assist in any care you may need, and be able to authorize emergency medical treatment if it becomes necessary.
You will be asked to remove all makeup (including nail polish), hairpieces, contact lenses, eyeglasses, dentures, and other portable devices.
An intravenous (IV) line may be inserted into your arm to prevent dehydration since you cannot eat or drink. The IV line will also allow easier administration of any medicines you may require. You will usually receive medication to assist you in relaxing and another that may make your mouth dry. If at any time you become anxious or uncomfortable, talk to the staff about the possibility of more medication to assist you.
If you are being treated for an AVM or similar problem you will have an angiogram the day of your treatment. If so, your groin area will be shaved before treatment or you will be asked to shave it before coming to the treatment facility.
The head frame is a guiding device which makes sure the Gamma Knife beams are focused exactly where the treatment is needed. It is a vital part of the treatment. While the frame may look “scary,” it is made of a lightweight aluminum alloy that only weighs three kilograms, or about 6½ pounds. The frame can be seen on the imaging equipment and provides your treating staff with an exact set of coordinates so that your lesion or tumor is targeted precisely.
Before attachment of the frame you will receive four minor injections of a local anesthetic, to numb you in the locations that the frame will be attached to your skull. Two injections will be in the forehead and two will be in the back of the head. The injections are given just under the skin and are only slightly uncomfortable. There is no pain during the placement of the frame but you may experience a feeling of pressure or tightness that will disappear in about 15 minutes. The pins are secured with a small drill. This guiding device will stay on your head until the Gamma Knife treatment is completed. Patients state they felt no pain, only some pressure, during this procedure.
Glasses cannot be worn with the frame on. You may wish to remove the ‘temples’ from a pair of old glasses and have the nurse tape them to your nose and forehead so that you can see better while waiting for treatment. During the actual treatment and during scanning, the glasses will have to be removed.
After the head frame is securely attached, you will be taken to an imaging area. If you have a tumor, an MRI or CT will be performed, which will show the location in relation to the head frame. Sometimes both an MRI and a CT scan are performed. If you are having an AVM or other vascular dysfunction treated, you will have a catheter inserted in an artery in your groin, and directed to your brain area. Contrast dye will be injected into the catheter and X-rays will be taken that will show the blood vessels in your brain in relationship to the head frame.
At this point you will be able to relax for at least an hour and maybe two. Your treating neurosurgeon and his team are now working together to computer plan your treatment. They will decide how many areas to treat and what the appropriate radiation dosage is for each area, and how they will target to optimally irradiate the lesion or tumor. This information is computer “locked in” for your treatment.
When the final plans have been meticulously reviewed for your treatment, your neurosurgeon will come to talk to you. By this time you may have been moved to the Gamma Knife Unit bed or couch. The physician will tell you how many treatments to expect and how long each treatment will be to receive the proper amount of radiation. The Cobalt60 source of radiation in the Gamma Knife emits radiation at a constant dose. Each treatment is calculated to allow the proper amount of time so that the proper level of radiation is received.
While lying down on the unit’s bed, your head frame will be attached to a helmet that was specifically selected for your treatment. The helmet has 201 holes, which means that each individual “ray” of radiation received is muted and will not damage healthy tissue. Each helmet used has different size holes for usage in different areas of the brain, where vital structures or nerves may be near. The team may change your helmet during treatment. Some of the holes in the helmet may be “plugged” to protect certain areas of your brain or eyes. The state of the art preciseness of the Gamma Knife unit, and the meticulous computer planning for targeted areas ensures that healthy tissue does not receive unnecessary dosages of radiation.
At this point the staff and physicians will go to the other room to administer your treatment. However, you will not feel alone, as you can talk with your physician through a microphone in the helmet, and a camera positioned on you allows the staff to see you at all times.
The bed or couch of the unit you are lying on will move backwards into the treatment hood. When this is about to happen, a bell will chime to warn you and the staff that the bed is about to move. You will hear a click as the helmet locks into the Cobalt60 radiation source and the ports open to allow the radiation through. During treatment, you will not feel or hear anything from the Gamma Knife unit. When the treatment is completed, the bell will chime again and the bed will move back out of the unit and you will hear the click of the unit closing.
The total treatment time may take two to four hours, depending on the size of the area to be treated and the dosages needed for effective treatment. You should be mentally prepared to spend this much time in the treatment room.
Immediately after your treatments are completed, the head frame will be removed. There is usually some minor bleeding from the pin sites. Gauze and an elastic bandage is usually temporarily applied. A very few people experience a headache or nausea once the frame is removed. Tell your nurse or doctor if you have a headache or nausea and need something to make you feel more comfortable.
At this time, you will be allowed to eat and drink. The IV may remain in your arm until the staff can see that you are tolerating liquids well. If you had an angiogram, you will need to lie flat in bed for up to eight hours, before you are allowed to get up and move around. This will help prevent headaches from the angiogram procedure itself.
You will normally be allowed to go home the day of treatment or the next morning, depending on what procedures you had done, and your specific condition. Usually there are no long term effects from Gamma Knife treatment. Some patients state that the pin sites are numb and “tingle” for a few weeks or intermittently for a longer period. This represents normal healing of the site, and has nothing to do with your tumor or lesion. A very few people lose a small patch of hair if the treated area was near the surface of the skull. The hair will usually grow back in a few months.
Anytime we “touch” the brain, whether with a scalpel or with radiation, the brain tissue reacts. Much like a bruise, the brain may experience some swelling in the future. This occurs because the radiation damaged the tumor or lesion DNA, and the cells lose their ability to replicate or to regulate fluids. If problems develop, your neurosurgeon may prescribe a mild steroid.