Gamma Knife Radiosurgery – How It Works

Gamma Knife® surgery is a bloodless surgical method that is recognized worldwide as the preferred treatment for selected lesions, tumors, and conditions that afflict the body’s most important organ: the brain. The Gamma Knife Center at the Samuel Oschin Comprehensive Cancer Institute is one of only a handful of facilities in the Los Angeles area to offer Gamma Knife surgery. Radiation distorts the DNA in cancer cells. The cells then lose their ability to reproduce. Conventional radiotherapy usually involves the delivery of large volumes of radiation, which may affect normal brain tissue as well as cancer tissue. Gamma Knife technology allows radiation to only touch very small tumors or lesions deep within the brain, leaving healthy brain cells alone. This treatment is safe, accurate, and effective. There is no “knife” in Gamma Knife: because no incisions are made, it avoids the risks and complications associated with traditional surgery. The treatment is performed in one day and usually does not require an overnight stay in the hospital.


The Gamma Knife can be used to treat a range of lesions, tumors and conditions affecting the brain, including:

  • Benign brain tumors, including acoustic neuromas, meningiomas and pituitary adenomas
  • Primary brain tumors, including hemangiomas, meningiomas, schwannomas, hemangioblastomas, and all forms of cancer that have spread to the brain
  • Arteriovenous malformations
  • Trigeminal neuralgia
  • Pineal tumors

Safe and Precise

More than 2,500 peer-reviewed articles support the use of the Gamma Knife surgery. Recognized as painless and effective, the Gamma Knife is accurate to the sub-millimeter level and is one of the most precise radiation instruments available.

The Process

Imaging, such as magnetic resonance imaging (MRI), computed tomography (CT) or angiography, is used to determine the exact size, shape and position of the target in the brain. Your physician, in consultation with a team of experts, then plans the treatment, during which 201 precisely focused radioactive beams are directed at the target in the brain. A stereotactic head frame allows the doctor to pinpoint the target to be treated with unparalleled accuracy.


Treatment using the Gamma Knife is painless, accurate and effective. The Gamma Knife is not a knife in the normal sense of the word. No incision is made and none of a patient's hair needs to be cut or shaved. In fact, the Gamma Knife is used in place of surgery. The Gamma Knife is accurate to the sub-millimeter level and is one of the most technically precise radiation instruments available. The shape and dose of the radiation is optimized to hit only the target, without damaging surrounding healthy tissue. Furthermore, treatment is performed in one session and patients can usually return home shortly after treatment.

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