About the Gamma Knife

HOW WE HELP?

A Non-Invasive Alternative
The Gamma Knife is an effective, non-invasive alternative to traditional brain surgery. This highly sophisticated technology precisely directs focused radiation to specific targets in the brain. Typically performed in a single outpatient treatment session without general anesthesia, this proven technique helps patients avoid incision, scarring, and long hospital stays while minimizing surgical complications. For many conditions, Gamma Knife treatment is the most accurate form of stereotactic radiosurgery available. See the FAQ for more detailed information about the Gamma Knife.

Conditions treated with the Gamma Knife include:

• Malignant tumors: metastatic tumors (cancer spread to the brain), gliomas, chondrosarcoma
• Benign tumors - acoustic neuromas(vestibular schwannomas), meningiomas, pituitary adenomas
• Vascular abnormalities - arteriovenous malformations
• Functional disorders - trigeminal neuralgia (also known as tic douloureux or chronic facial pain)

Candidates for Gamma Knife Treatment
Neoplastic and vascular disorders account for the majority of radiosurgical procedures today. The Gamma Knife is effective in controlling tumor growth and hemorrhaging from vascular malformations and targets lesions so exactly that the risk of harming healthy tissue is minimized. In certain cases, Gamma Knife treatment may serve as an adjunct to standard neurosurgical therapy or as the preferred course of treatment when further traditional therapy is not recommended.

Gamma Knife treatment is often the preferred alternative for patients who are not candidates for conventional neurosurgery or radiation therapy. It also may be recommended as an additional therapy for individuals who have already undergone surgery or radiation and require further treatment.

The Gamma Knife may also be recommended for patients with the following conditions:

• Tumors or vascular malformations that are surgically inaccessible
• Risk factors that make surgery inadvisable
• Need for an additional dose of radiation following conventional radiation therapy
• Recurrent tumors
• Facial pain

Our multidisciplinary team (including neurosurgeons, radiation oncologists, radiation physicists, neuroradiologists, oncologists, neurologists, nurses and radiation therapists) evaluates each patient to determine whether Gamma Knife treatment is the best option. The patient's medical history is reviewed, along with imaging studies and information provided by the patient's physician. If Gamma Knife treatment is not considered appropriate, the team will suggest an alternate treatment option.

Conditions Treated

Malignant tumors 45%

• Control rates of 80-90 percent for metastatic tumors, essentially comparable to open surgery – with fewer risks and shorter hospital stays.

Benign tumors 29%

• 90 percent control rate at ten-year follow-up.

Vascular abnormalities 12%

• Complete obliteration of arteriovenous malformations in 60-70 percent of patients within two to three years.

Functional disorders 14%

• For trigeminal neuralgia, initial pain relief in over 80 percent of patients; long-term pain relief without medications in 63 percent of patients at four-year follow-up.

TREATMENT & FOLLOW-UP

Once you decide to have Gamma Knife treatment, you will come to the USC University hospital Knife Unit and check in with our staff. You will be asked to sign a consent form that grants us permission to perform the procedure.

Gamma Knife treatment consists of the following steps:

1. Placement of the head frame: A stereotactic frame will be placed on your head and remain there throughout treatment. The frame is needed as a reference point during treatment planning, and it is used to hold your head in the exact position required for precise treatment.

2.  Obtaining precise images: MRI, CT scans or angiography (a way to visualize the blood vessels) will be used to obtain images that clearly define where the tumor, AVM or treatment site is located. After the required images are obtained, you can relax while the team reviews them and plans your treatment.

3. Treatment planning: Once the images are transferred to the Gamma Knife's computer planning system, the team will examine them and accurately define the target. The detailed treatment plan they create will determine how long treatment will take. A typical Gamma Knife treatment planning takes an hour or two.

4.  Treatment: Once the treatment plan has been carefully checked by the team for precision and safety and has been explained to you, treatment will begin. You will enter the Gamma Knife room and recline on the couch portion of the unit. The team will position your head in the helmet, which directs the radiation to the exact treatment target. The team conducts treatment in an adjacent room, maintaining contact with you through video and intercom. You may choose to listen to the radio or music of your choice. When your treatment is over, the head frame is removed and you can leave the center. Most individuals return to normal activities within a day or two.

5. Post Gamma-Knife treatment: Your physician will monitor your treatment results by taking periodic MRI, CT scans or angiography. USC University Hospital Gamma Knife Unit staff will stay in contact with your physician in order to monitor your progress. We are available 24 hours a day to provide further consultation on your case.