The CyberKnife VSI is a robotic stereotactic radiosurgery system that achieves surgical like results using highly focused radiation to kill benign or malignant tumors. The system consists of a compact linear accelerator mounted on a robotic arm. It is controlled by computers and guided by real-time x-ray images throughout the delivery of high dose radiation. The robotic system is able to detect and adjust for minute changes in patient or target position, even locking on to a target that moves during breathing.
CyberKnife VSI treats tumors and benign lesions of the brain, spine and soft tissue in areas such as lung, liver, pancreas and prostate. Primary and metastatic tumors as well as functional diseases, such as arterial venous malformations (AVM's) and trigeminal neuralgia, can be treated by CyberKnife VSI.
Radiosurgery is not an appropriate treatment option for every patient or disease. CyberKnife VSI is appropriate whenever stereotactic radiosurgery is appropriate. CyberKnife VSI stereotactic radiosurgery is often used in conjunction with traditional therapies such as radiation therapy, chemotherapy or surgery. CyberKnife VSI may also be the best, or the only, option for some patients in the following circumstances:
* recurrence of a tumor next to a critical structure such as the spine, that has already received its maximum lifetime dose of radiation
* tumor located close to a critical structure such as optic nerves, where traditional radiation therapy would pose significant risk of damage to that structure
* when a surgical approach would be too difficult
* when surgery is unable to remove all of the diseased tissue
* when the patient is unable or unwilling to undergo traditional surgery.
The patient and their primary care physician may seek a CyberKnife VSI consultation with the CyberKnife VSI clinical team. Every consultation includes the CyberKnife VSI radiation oncologist and surgeon. If treatment is appropriate, the CyberKnife VSI coordinator arranges for imaging studies from which the CyberKnife VSI surgeon, radiation oncologist and physicist jointly plan and approve a course of treatment. The treatment is completed in 1 to 5 sessions lasting 45 to 90 minutes.
Although both methods use high energy radiation, stereotactic radiosurgery differs from traditional radiation therapy or intensity modulated radiation therapy in several ways. CyberKnife VSI treatments are more accurate due to the ability of the robot to point to the target from more than 1,000 possible positions with sub millimeter precision. This means that the target can be fully treated while minimizing radiation to immediately adjacent structures. High accuracy enables a full treatment in 1 to 5 sessions rather than 25 to 40 sessions.
CyberKnife VSI is "patient centric" meaning that the system finds and then adjusts itself to the location of the patient and tumor. There is a much wider variety of treatment angles and fields for the computer to choose from. Gamma Knife radiosurgery and linear accelerator (gantry) based treatments are "isocentric" meaning that the target must be brought into the center or focal point of the treatment device. A rigid head frame is required for gantry based or Gamma Knife radiosurgery, which is confined to targets within the brain. CyberKnife VSI does not require the use of a rigid frame so targets can be treated throughout the body.
CyberKnife VSI achieves surgical like results without open surgery. Hence there is no anesthesia, no blood loss, and no post-surgical recovery. Patients typically resume normal activity on completion of the procedure. CyberKnife VSI stereotactic radiosurgery is appropriate wherever traditional stereotactic radiosurgery is indicated. Historically, stereotactic radiosurgery has been confined to intracranial lesions. The clinical literature for soft tissue radiosurgery is being developed, as CyberKnife VSI is the first technology that is able to perform this type of treatment beginning in 2001.