STEREOTAXIC RADIOSURGERY - COMPARING DIFFERENT TECHNOLOGIES

RADIOSURGERY CAN BE DEFINED as 3-dimensional stereotactic irradiation of small intracranial targets by various radiation techniques. The goa l is to deliver, with great accuracy, a large, single fraction dose to a small intracranial target, while minimizing the absorbed dose in th e surrounding tissue. This article describes certain technical aspects of radiosurgery and compares the different methods of performing such treatment. The 2 most frequently used types of devices for radiosurge ry are units with multiple cobalt sources (e.g., the Gamma Knife) and those based on a linear accelerator. In the former, highly collimated beams of radiation from the cobalt sources intersect at the target. In the latter, the source of a highly collimated beam of high-energy pho tons directed at the target turns through an are or set of arcs. The a ccuracy of target localization, the steepness of fall-off of the radia tion dose outside the target and the ability to irradiate an irregular ly shaped target are all comparable for these 2 types of devices, desp ite claims to the contrary.