CyberKnife is a machine used to deliver the latest stereotactic radiotherapy. It uses a moving couch and a small linear accelerator on a robotic arm to deliver multiple beams of radiation from different angles. It works best on small tumours with well-defined edges. CyberKnife is able to deliver multiple doses of highly concentrated radiation from a variety of angles. It can also adjust the delivery, for example to match the patients breathing motion.