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Gamma Knife Radiosurgery Radiosurgery is a word coined by neurosurgeon Lars Leksell in Sweden 50 years ago. He knew that a single high dose of radiation would kill cells and he worked out a way to create a focus of radiation at a precise spot inside the body to kill tumor cells, calling the method radiosurgery. After trying several methods, Leksell and physicist Borje Larson invented the Gamma Knife. Gamma rays are high-powered X-rays and they used radioactive Cobalt as their sources. They created a helmet with 201 holes in it to allow small beams of gamma rays to pass through to a focal spot. Each beam by itself was too weak to do any damage to tissue, but where they all came together, a small spot of high intensity radiation was created. Leksell had already developed a guidance system for open brain surgery, called a stereotactic (touch in space) frame. He used that to align the patient’s tumor up with the focus of gamma rays. It works amazingly well. I have used the Gamma Knife here in Dallas since 1989 and have treated hundreds of patients. Here is a list of treatable conditions: Brain Tumors Metastatic Tumors – tumors that have spread to the brain from elsewhere. Breast, lung, kidney, colon and melanoma are the most common. Even multiple areas of metastatic cancer in the brain can be treated. The response rate of treated tumors is good, but the risk of new tumors showing up is fairly high. The Gamma Knife is the only device cleared by the FDA for radiosurgery of brain metastases. Acoustic Neuromas (Vestibular Schwannomas) – benign in nature but in a difficult place for surgery. Gamma Knife is the treatment of choice unless the tumor is too big. Meningiomas – benign but some are deep and inoperable or encasing arteries. Response rate is the same or better than open surgery, with minimal risk. Pituitary tumors – through the nose surgery is first choice, with Gamma Knife used to inactivate portions that either could not be removed surgically or that re-grow. Astrocytomas, Glioblastomas, Gliomas – not suitable for radiosurgery because they infiltrate diffusely in the brain. Open surgery and external beam fractionated radiation is the primary treatment. Occasionally a case of recurrent tumor is treatable with radiosurgery. Trigeminal Neuralgia Gamma Knife irradiation of the trigeminal nerve right at its entry into the brain gives relief about as good as surgery without any of the risk. The Gamma Knife is the most accurate and precise instrument for radiosurgery and I believe the only safe way to do radiosurgery on the trigeminal nerve with success. The success rates are: 50% pain-free without medicine; 25-30% pain-free but still on some medicine; 20-25% partial or no relief. The recurrence rate is about 25% and pain can recur in one to five years. Gamma Knife treatment can then be repeated if necessary. For a more complete
description and discussion of Gamma Knife radiosurgery, visit the web
site at: http://www.gammaknife.org.
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