gamma knife

CyberKnife Radiosurgery

UCSF began offering CyberKnife treatments in 2003, and is one of the few centers in California that offer this service.

In many cases, patients treated with the CyberKnife today would have previously been considered untreatable with surgery or conventional radiation therapy. Currently the CyberKnife is located at the Mt. Zion Hospital in the Department of Radiation Oncology.

CyberKnife radiosurgery is an advanced radiation technique that precisely delivers a high dose of radiation to tumors anywhere in the body. As a painless, non-invasive procedure, it does not involve an actual knife, but is called “radiosurgery” because of its precision. It is considered a type of stereotactic radiosurgery

The CyberKnife device emits a narrow beam of radiation from a robotic arm that moves around the patient’s body to accurately target a tumor. Using brain scans taken before and during the procedure, the robotic arm automatically tracks and compensates for small movements. A precise map of the tumor’s location in the brain is continually updated throughout the procedure, so the patient can just lie down normally on the treatment bed without anesthesia. The flexibility of the robotic arm also makes it possible to treat areas of the body, such as the spine and spinal cord, that cannot be treated by other radiosurgery techniques.



Generally, CyberKnife radiosurgery treatments are split into 1-5 daily sessions, each lasting 30-90 minutes. The number and total dose of radiation treatment depends on the size, location, and shape of the tumor. 

The precision of advanced radiosurgery techniques minimizes radiation exposure to the healthy tissue surrounding a tumor. UCSF offers three delivery systems for radiosurgery: the Gamma Knife for intracranial tumors, and Cyberknife and TrueBeam for intracranial, spinal and other body sites. 

The team at UCSF will determine which radiosurgery technique is the best treatment for each patient, but the Gamma Knife is generally used for small benign or malignant intracranial brain tumors, while the CyberKnife and TrueBeam excel at treatment of spine tumors and other body sites. 

Ultimately, the recommendation for CyberKnife treatment depends on a number of factors, including tumor size and location, as well as the patient’s overall health and medical history. However, tumor types that may be considered for CyberKnife radiosurgery include the following:

  • Large benign or malignant brain tumors not suitable for single session treatment
  • Metastatic spine tumors


This content was reviewed by UCSF radiation oncologist David Raleigh MD, PhD.