The CyberKnife radiosurgery system for lung cancer.

The CyberKnife is a frameless image-guided radiotherapy system involving a 6-MV linear accelerator mounted on a robotic arm. The imaging system consists of two diagnostic x-ray sources mounted to the ceiling paired with amorphous silicon detectors to acquire live digital radiographic images of the tumor or tumor surrogates including bony anatomy or implanted fiducial markers. The Synchrony system enables 4D real-time tracking of tumors that move with respiration. Owing to this complex system, moving tumors can be treated with an accuracy of 2 mm or less while patients breathe normally. Clinical results of inoperable patients with peripheral early-stage lung cancer are excellent. The toxicity is low and the treatment does not result in a loss in quality of life.