What is Cyberknife ???. 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. More info visit: http://goo.gl/GTSE93