Gamma Knife
Radiosurgery with the Gamma Knife is a is a pain-free, noninvasive, form of radiation therapy used to treat brain tumors, vascular malformations, and other abnormalities without surgical incisions.
The Gamma Knife is not an actual knife but instead a machine that focuses approximately 200 microbeams of radiation with submillimeter precision on a tumor or other target. Although each beam has a negligible effect on the brain tissue it traverses, minimizing radiation exposure to surrounding healthy tissue, a high dose of radiation is delivered at the intersection point of all beams.
Typically, Gamma Knife radiosurgery is a treatment that is completed in a one day after a single session.
Diseases treated with Gamma Knife Surgery
Gamma Knife surgery can be used to treat the following brain disorders:
- Brain metastases, pituitary adenomas, pinealomas, craniopharyngiomas, meningiomas, chordomas, chondrosarcomas, and glial tumors
- Acoustic neuroma (vestibular schwannomas), a benign tumor that forms around the nerves responsable for balance and hearing that connect the inner ear to the brain.
- Arteriovenous malformations, which are are abnormal, tangled blood vessel formations.
- Tremors caused by diseases such as essential tremor or Parkinson’s disease.
- Trigeminal neuralgia is a chronic condition that affects a facial nerve and causes excruciating pain.
- Various forms of epilepsy.
The Gamma Knife may be useful if the patient has a brain lesion or tumor that cannot be reached by traditional surgery techniques or if he is physically or medically unable to undergo surgery. It may also be combined with conventional surgery to prevent regrowth of the tumor.
Preparation for Gamma Knife Surgery
Initial procedures vary depending on whether the Gamma Knife system employs an external rigid head frame or a frameless mask.
If a head frame is used, then first the frame is placed on your head, composed of aluminum and that weighs less than 1 kilogram. The frame serves as a “reference” during treatment planning and is essential for keeping the target perfectly aligned during the treatment.
In order to get the frame in position, you will receive four local anesthetic injections, two in the back of your head and one on each side of your forehead. In these locations, special pins are used to secure the head frame to the skull. As the pins are tightened, you may feel some pressure, but this typically only lasts a few minutes. After positioning the head frame, a radiation therapist will take head measurements. Typically, a CT or MRI scan is performed with the head frame in place. These measurements and scans are used for treatment planning.
Gamma Knife treatment is also available without a frame by using a thermoplastic mask over the face. The mask is then attached to the Gamma Knife table’s existing frame and the patient’s head is completely immobile.
The remaining steps for both systems with and without a frame are identical.
An IV line may be inserted into your arm and enables the delivery of contrast agent (a type of dye) for your computed tomography (CT) and/or magnetic resonance imaging (MRI) scan. These scans and dye are used to pinpoint the precise location, size, and shape of the lesion or tumor to be treated. Typically, scanning takes approximately 30 minutes to complete.
The intravenous line can also be used to administer a small dose of sedative to help you relax (if needed). The majority of patients are awake but lightly sedated during the procedure. In certain instances (typically with children), general anesthesia is utilized.
Your neurosurgeon, the radiation oncologist, and other team members will plan your treatment on a computer using results of the scans and other data. They will determine the areas to treat, the radiation dose, and the optimal method for targeting the lesion, by placing the target exactly in the center of approximately 200 precision-aimed, converging beams of Cobalt-60 generated gamma radiation.
Gamma Knife Icon
The Gamma Knife system is improved with each new model; among other advantages over previous models, the most recent Leksell Gamma Knife Icon:
- Uses either a head frame or a face mask without a frame to secure the head during treatment.
- Both small and large tumors are treated.
- Allows to treat lesions close to vital structures
- Earlier models only utilized a head frame, which is unnecessary in certain circumstances. The face mask is frequently more comfortable for patients than the head frame. Both options are available and allow neurosurgeons to recommend the most suitable option for your specific condition.
In comparison to other radiosurgery systems, the Leksell Gamma Knife Icon is superior in its capacity to preserve healthy brain tissue. To ensure complete destruction of the lesion, other radiosurgery systems must deliver high doses of radiation to a specified margin of healthy tissue surrounding the lesion. Due to the high accuracy and precision of the Leksell Gamma Knife Icon model , this added margin is reduced to 1 mm, or roughly the thickness of one sheet of paper.
Avoiding unnecessary radiation is especially crucial for children, who may be more susceptible to radiation’s later effects than adults.
Gamma Knife Surgery
When the treatment begins your frame attached to your head or frameless mask is secured to the table of the Gamma Knife to prevent head movement during the treatment. The table moves slowly into the radiation-delivering Gamma Knife machine. During your treatment, the medical team will be immediately outside the room and you will be constantly monitored and observed by cameras. A microphone is located close to your head so that you can easily communicate with the staff during your treatment.
Depending on the size, shape, and location of the lesion and the number of radiation doses, the majority of treatments last between 30 minutes and three hours.
The Gamma Knife procedure is painless. You will not experience any heat, noise, or discomfort during the treatment. You are welcome to listen to music or take a nap during the procedure.
Following your treatment, the table will be move out of the Gamma Knife machine and the staff will enter the room. The head frame/mask and IV of the patient will be removed.
You will be discharged from hospital quickly following the procedure. Some patients suffer from mild headaches that are treatable with medication. Depending on the type and size of the tumor or lesion, it may be necessary to undergo multiple treatment sessions according to the treatment plan suggested by the neurosurgeon and/or radiation oncologist.
Benefits of Gamma Knife Surgery
The advantages of Gamma Knife surgery over conventional surgery are numerous:
- No incisions or general anesthesia are required.
- Can treat brain tumors/lesions that cannot be safely reached by conventional surgery.
- Can treat multiple tumors/lesions simultaneously, like in the case of brain metastases.
- Avoids other surgical risks and complications such as bleeding and infection from incisions.
- Limits damage to the healthy surrounding tissue.
- Discomfort or pain following treatment are minimal or completely absent.
- Typically carried out as an outpatient procedure (rarely requires an overnight stay in the hospital).
- Allows return to normal activities within two days.
- Typically does not necessitate physiotherapy or other forms of rehabilitation.
- Compared with large field radiation, you will not lose all your hair or experience the loss of cognitive functions that can accompany radiation to the entire head.
