Stereotactic Radiation Therapy

Stereotactic radiation therapy (SRT) developed from its precursor, stereotactic neurosurgery. The term 'radiosurgery' was coined by neurosurgeon Lars Leksell in 1951 just as Sir Victor Horsley coined the term 'stereotaxis' in 1908. The originally published technique involved the precise direction of an external beam of radiation (x-ray, protons, gamma rays, or high energy photons) at a stereotactically defined target. Collaborations with nuclear physicists, beginning in Berkeley, California, in 1954, harnessed the penetration of extremely powerful protons and other light ions to ablate tumors located deep within the brain. Leksell and collaborators developed the Gamma Knife, a massive device containing 201 cobalt-60 sources precisely directed to an extremely small volume. It was used successfully in Stockholm for many years and later was commercialized and used all over the world. Existing linear accelerator radiation therapy treatment devices were later modified to mimic the Gamma Knife technique. Ultimately, dedicated SRT linear accelerators were marketed. These types of intracranial SRT proved so successful in treating brain disease that similar techniques (sometimes fractionated) were adapted for extracranial targets. Stereotactic body radiation therapy (SBRT) was first performed in Stockholm in the 1980s. Development of image-guided SBRT has become well accepted in modern radiation therapy departments.