Preparing For Gamma Knife Treatment
The evening before your treatment you should wash your hair and avoid using any hair cream or sprays. You will not be allowed to eat or drink anything after midnight. This will decrease the chance of stomach upset during the procedure. Heart or blood pressure medications can be taken with a small sip of water on the morning of your procedure. Pack all the prescription medications that you are currently taking into a small bag to bring with you the following morning and make a list of medications to which you are allergic.
Arrive at the Gamma Knife® Center the morning of your procedure. You’ll be asked to change into a hospital gown and to remove jewelry, eyeglasses, contact lenses, dentures, wigs or hairpieces. A mild sedative will be given to you through an IV.
Head frame Application
Before the procedure, a lightweight box-shaped frame is attached to your head with four pins. The head frame holds your head still during the procedure and serves as a reference point in determining where the beams of radiation will converge. A local anesthetic is injected in the four areas where the frame is attached to the head with mounting pins, similar to how a dentist numbs your mouth when you have a cavity filled.
You’ll feel a slight pressure during the head frame application, but this sensation only lasts a few minutes and usually goes away when the head frame is in place. You will be able to move your head after the head frame is applied. The stereotactic frame will remain on your head until after the completion of your Gamma Knife treatment.
Imaging To Pinpoint The Target
After the frame has been placed on your head, a clear plastic helmet will be placed over the frame to measure the configuration of your head. The helmet contains holes to allow for comfortable breathing during the procedure. You will then have imaging studies — such as CT (computed tomography), MRI (magnetic resonance imaging) or conventional X-rays of brain circulation which may include the injection of a substance that makes the blood vessels show up (cerebral angiography) — to help the surgeon plan your treatment. These results are then fed into the gamma knife’s computerized planning system. You may have had these studies performed before, but they must be repeated with the head frame in place to precisely map the area to be treated. You should feel no pain during this time.
When the imaging studies are completed, you will be allowed to rest, watch TV or listen to music while the medical staff plans your treatment. Your treatment planning team includes your neurosurgeon, radiation oncologist and medical physicist. It may take up to an hour or two to calculate the target coordinates and radiation dose, depending upon the complexity of the treatment plan. During that time, family members may visit you or stay with you until the treatment begins. Return home the same day and resume your normal routine almost immediately
Computerized Dose Planning
Physicians use computers to plan the radiation surgery so it matches the desired target. The number of minutes that each radiation dose lasts is determined during dose planning and is dependent upon the size and number of areas to be targeted. The procedure usually includes multiple doses that are delivered one after the other, all on the same day.
Your Gamma Knife Treatment
When the radiation plan is ready, it is time for your treatment. You’ll be asked to lie on the Gamma Knife couch where you’ll be positioned into a guiding device that holds your head securely in the Gamma Knife helmet. Your head frame will be connected to a device known as a collimator helmet. The helmet has 192 holes through which the radiation beams will pass.
The treatment begins when the doors of the radiation unit open and the head of the couch slides into the treatment position. You will hear a small click as the collimator helmet securely attaches with the machine, at which time, you will neither hear nor feel any effects from the treatment. After you’re placed in the correct position, the staff will go into an adjoining room to monitor the procedure via video cameras. An intercom system allows you to communicate with the physicians and nurses during the procedure. Treatment times vary, depending on the size and number of the targets.
Following Gamma Knife Treatment
When your treatment is completed, the frame will be removed. An antibiotic ointment will be applied to the pin sites over which gauze will be placed followed by a head bandage. On rare occasions, there may be bleeding at a pin site which does not stop with pressure from the gauze. If this occurs, your doctor will use a stitch to close the pin site.
Virtually all patients go home the same day as their surgery. Generally you’ll experience no immediate side effects from the Gamma Knife procedure other than a mild headache or nausea. Should this occur, your nurse can give you medications ordered by your doctor to relieve the headache or nausea. Side effects are rare because only the abnormality is targeted; the surrounding healthy brain tissue is minimally affected. When you are able to tolerate fluids by mouth, your intravenous line will be removed by the nurse.
Your follow-up care will be coordinated with the doctor who referred you and the doctors involved in your treatment. If you are discharged the day your procedure was performed, you must have someone drive you home and stay with you for that night.