15.1.2: Stereotactic Radiosurgery

SRS is a multidisciplinary technique that involves:

  • Neurosurgery (more experience with brains, both benign and malignant conditions, expertise at surgical alternatives, less risk averse)
  • Radiation Oncology (experience with radiotherapy/physics/radiobiology,
  • Radiation Therapists
  • Medical Physicists

History of Radiosurgery

Developed by Lars Leksell who pioneered the use of a stereotactic frame which used cartesian co-ordinates. This allows the delineation of any point within the brain on an x,y,z co-ordinate system. If this is matched to a 3D image of the brain (acquired through MRI with fiducial markers). Stereotactic radiosurgery was pioneered first which allowed accurate localisation of brain tumours. Leksell then developed an orthovoltage attachment to the Leksell frame that allowed for delivery of multiple beams which focussed on a single point within the brain.
This concept was then developed further into the Gamma Knife. Instead of a single orthovoltage beam that moved around, the Gamma Knife contains 192 separate 60Co sources. The first commercial version was produced in 1981 in Los Angeles.

More Recent Developments

Imaging of brain lesions first with CT and then MRI has allowed more accurate definition of tumour sites within the brain. More accurate imaging has also allowed the development of frameless techniques, which are more comfortable for patients and are close (but not quite as accurate) as stereotactic frame techniques.