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The Science Behind the CyberKnife

Last Updated 3/11/2011 4:22:50 PM

How does CyberKnife work? To aggressively treat cancer--lung cancer, brain cancer (brain tumors), and other forms of cancer, the CyberKnife uses a miniaturized linear accelerator, modified for medical use, that is attached to a robotic arm--similar to those used in automobile assembly lines for welding parts. The Center for Advanced Radiotherapy and CyberKnife Radiosurgery at El Camino Hospital serves as a showcase site where, in addition to treating patients, doctors perform research, incorporate the latest innovations in the technology, and train and host visiting physicians from around the world.
While the patient rests comfortably, the CyberKnife's robotic arm can move around him or her in a nearly 360-degree arc; multiple beams of radiation target a tumor. This mechanism allows the CyberKnife to be used to treat cancerous tumors anywhere in the body; it was originally designed by Dr. John Adler of Stanford University to treat brain tumors, because of its ability to avoid normal tissue, but now it is also often used to treat lung cancer and, increasingly, to treat tumors in the prostate, liver and pancreas, and many other parts of they body.
Much of the CyberKnife's sophistication comes in its software programming. It can deliver targed radiation to a precise area of the body because it can recognize when a patient--or the patient's cancerous tumor--moves, and it can make instantaneous adjustments to accommodate that movement. In most cases, the patient's skull or skeleton or implanted markers are used to assist in localization of the cancerous tumor. In some instances, the patient wears a special light-emitting-diode (LED) vest, which the CyberKnife uses to gauge movement caused by respiration, and several X-Ray cameras, all of which are used by the system's software to track position and movement.
This image-guided approach differs from some other forms of stereotactic radiosurgery (which means that they use three-dimensional targeting to precisely beam radiation at cancerous tumors from multiple angles). With the Gamma Knife, for example, a rigid metal frame is typically affixed to the patient's skull with screws. These frames are available only for human skulls, limiting treatments to brain tumors, and of course, they can cause discomfort or pain to the patient. Other companies have modified the same linear accelerator that has been used for more than 50 years to create devices to perform radiosurgery for the treatment of cancer, but the CyberKnife was designed specifically to overcome the limitations of the Gamma Knife and traditional linear accelerators by utilizing the latest in robotics and computer technology.