Radiosurgery

Radiosurgery is a treatment method using ionizing radiation—high-energy radiation that ejects electrons from atoms—concentrated on a small area inside the body. The term "surgery" is used because its effect resembles removal of diseased tissue or lesions, even though no actual incision or opening of the brain is made.

The key principle is directing many radiation beams from different angles, all converging at a single point. Consequently, diseased tissue in that target area receives a very high dose of radiation, while healthy tissue along each beam pathway receives a low dose. This is called stereotactic convergence, which relies on precise imaging such as MRI and CT scans.

History and origins

The term and method were developed by Swedish neurosurgeon Lars Leksell in the late twentieth century. He designed a radiation apparatus emitting from several hundred cobalt sources all precisely converging at a single point—equipment that became known as the Gamma Knife. Subsequently, conventional linear accelerators were also adapted to perform similar work.

Types of equipment

Three approaches are common: cobalt-60 equipment (Gamma Knife), used mainly for brain targets; adapted linear accelerators (including robot-based systems such as CyberKnife) usable for brain and other body sites; and equipment using particle beams such as protons, whose energy is deposited at a specific depth, sparing tissue beyond the target.

Medical use

It is most often used for small brain tumors, tumors that have spread from elsewhere (metastases), vascular malformations (AVM), and facial nerve pain (trigeminal neuralgia). When applied to other body sites—such as the lungs, liver, or spine—it is called stereotactic body radiotherapy (SBRT). Choice depends on tumor size, location, and proximity to sensitive structures such as the optic nerves.

Benefits and limitations

The method allows patients to avoid general anesthesia, bleeding, and prolonged hospitalization, typically completing in one or several sessions. Limitations include that effects develop gradually—small stopped tumors do not shrink as quickly as with conventional surgery—and the target lesion must be small and well-defined. Potential side effects include damage to surrounding tissue and, over time, effects on healthy tissue.