About the Procedure

The patient arrives at the hospital the morning of the procedure and is started on intravenous fluids. The surgeon then affixes the stereotactic frame to the patient's head using small pins the size of a pencil tip. The head frame is a guiding device which makes sure the Gamma Knife beams are focused exactly where the treatment is needed. Mild sedation and a local anesthetic for the pin sites are administered prior to headframe placement.

The patient then undergoes the appropriate imaging studies (MRI, CT and/or angiography) to precisely localize the target tissue to be treated in reference to the attached head frame.

While the patient rests, the team of Gamma Knife physicians and technicians utilizes three dimensional computer imaging to develop the patient's radiosurgical treatment plan. This typically takes one to two hours to complete.

Once the individualized treatment plan is completed, the patient is placed on the Gamma Knife couch. The stereotactic frame is attached to the collimator helmet containing the 201 portals through which the radiation beams are focused and set to the target coordinates.

After all stereotactic coordinates are checked, the couch is moved into the unit by an electrical motor and treatment begins. During the treatment, there is no noise and the patient feels no pain.

Communication is maintained with the patient at all times via video cameras and an intercom. Treatment time typically varies between 20 minutes and two hours depending on the complexity of the treatment plan and number of isocenters required. At the conclusion of the treatment, the stereotactic frame is removed and the patient is sent to his or her room after a brief period of observation. Occasionally, patients are observed overnight before being discharged and sent home. They can return to work and full activity the next day.

Treatment Results

Over 300,000 patients in over 200 select facilities worldwide have been treated with the Gamma Knife.

Listed below are treatment results for specific conditions:

• Metastatic tumors: Gamma Knife radiosurgery achieves control rates of 80-85 percent, essentially comparable to open surgery – without the risk of infection, bleeding or complications – and without a lengthy hospital stay and convalescence.
• Benign tumors: Follow-up of ten years demonstrates control rates in more than 90 percent of cases. Fifty-three percent of tumors decrease in size while 40 percent remain stable in size. In some cases, combined treatment with surgery and Gamma Knife offers the best opportunity for tumor control.
• Acoustic neuromas (vestibular schwannomas): Up to 98 percent of tumors either decrease in size or remain stable, with near complete facial nerve preservation, at six-year follow-up.
• Pituitary adenomas: Effective control in a majority of patients; particularly beneficial for residual or recurrent tumors following surgery.
• Vascular malformations such as arteriovenous malformations (AVMs): Complete obliteration of AVMs takes place in 60 to 70 percent of patients within two to three years of treatment.
• Trigeminal neuralgia: Initial pain relief in more than 80 percent of patients; long-term pain relief without medications in 63 percent of patients at four-year follow-up.