Computer aided robotic radiosurgery.

Radiosurgery involves the precise delivery of sharply collimated high-energy beams of radiation to a distinct target volume along selected trajectories. Historically, accurate targeting required the application of a stereotactic frame, thus limiting the use of this procedure to single treatments of selected intracranial lesions. However, the scope of radiosurgery has undergone a remarkable broadening since the introduction of image-guided robotic radiosurgery. Recent developments in real-time image guidance provide an effective frameless alternative to conventional radiosurgery and allow both the treatment of lesions outside the skull and the possibility of performing hypofractionation. As a consequence, targets in the spine, chest and abdomen can now also be radiosurgically ablated with submillimetric precision. Meanwhile, the combination of image guidance, robotic beam delivery, and non-isocentric inverse planning can greatly enhance the conformality and homogeneity of radiosurgery. The aim of this article is to describe the technological basis of image-guided radiosurgery and provide a perspective on future developments. The current clinical usage of robotic radiosurgery will be reviewed with an emphasis on those applications that may represent a major shift in the therapeutic paradigm.