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Frequently Asked Questions


The Swedish inventor, Professor Lars Leksell, coined this term because the machine utilizes gamma radiation from a cobalt source to destroy tumors or treat other brain pathologies. It acts like a surgeon’s scalpel—thus the “knife”—in its ability to precisely conform the radiation to a tumor shape.
The Gamma Knife was invented in 1968 in Sweden, where the first clinical treatment was delivered. The first U.S. unit was installed in 1988 at the University of Pittsburgh. The managing entity of The Southern California Regional Gamma Knife Center has been developing centers since 1993. Physicians at these centers have performed thousands of Gamma Knife procedures.
No, it is not experimental at all. It was approved by the FDA in 1988 and has been used to successfully treat patients worldwide at state-of-the-art treatment cancer centers.

It is using “radiation” in the function of “surgery,” thus radiosurgery. This differs from “radiation therapy,” which requires many weeks of daily fractions of radiation to a much larger area of brain tissue.

The Gamma Knife is used to treat brain metastases (tumors that start in the body and spread to the brain) such as lung cancer, breast cancer, melanoma, etc. It is used to treat benign tumors such as meningiomas and acoustic neuromas and for treatment of Arteriovenous Malformations (AVMs). The pain syndrome of trigeminal neuralgia, and the tremor of Parkinson’s disease may also be treated with the Gamma Knife. Utilizing the Gamma Knife to treat epilepsy and OCD is an area of extensive research. Finally, the most malignant tumors of the brain, the glioblastoma multiforme or anaplastic astrocytomas, as well as a number of other primary tumors of the brain, can be treated.

For tumors, the very intense dose of radiation directed precisely at the tumor causes the DNA and proteins in the cell to render themselves unable to divide. The tumor cells can then no longer live, and slowly die over time. The waste is then removed by circulating white blood cells. For AVMs, the radiation causes the blood vessels to thicken and scar until flow ceases. For trigeminal neuralgia, the protective covering or insulation around the pain nerves is destroyed, thus making the nerve unable to conduct an impulse of pain.
The Gamma Knife can treat certain head and neck tumors, but it cannot treat any pathology below the neck.
Gamma Knife radiosurgery is performed as an outpatient procedure. You will arrive at the facility on the scheduled treatment date. Because of the need for extreme accuracy in treating anything in the brain, a special frame is attached to the skull using four pins. The area of the pins is injected with local anesthetic (Lidocaine) and the pins are placed while the patient is under sedative anesthesia. Therefore, most patients have no recollection of the frame being placed and have no pain at all. You will then be transported for the appropriate high resolution imaging (generally an MRI). These images are then electronically transferred to the Gamma Knife suite for treatment planning. The finalized treatment plan will be presented to you for final consent prior to your placement into the Gamma Knife unit. Once you are positioned, Gamma Knife treatment will begin. The treatment, including prep time, takes several hours with the actual time inside the Gamma Knife varying from about 10 minutes to 90 minutes. Gamma Knife treatment is virtually painless. Upon completion of treatment, the head frame will be removed painlessly and you will be allowed to recover prior to your discharge home.
The side effects depend on the area of the brain of a patient’s pathology. In general, there is a 6% risk of temporary neurologic deficit, and a 3% risk of permanent neurologic deficit. This means that 97% of the treatments using Gamma Knife have no permanent side effects at all. These statistics are far superior to those of open craniotomy (brain surgery) for similar pathologies.
Because of the superior results and short hospital stays using Gamma Knife technique instead of craniotomy, essentially all insurance companies, including Medicare and MediCal, cover the procedure. Check with your insurance provider regarding your specific coverage.


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