Stereotactic radiosurgery (SRS) implies the delivery of a single, high dose of radiation using stereotactic techniques. Classically, for cranial SRS, a rigid neurosurgical frame is attached to the patient’s skull, and a stereotactic localizing device is attached to the frame to allow for improved targeting accuracy. Commercial SRS systems are available in which immobilization is achieved without a rigid neurosurgical frame. While there are innumerable commercial SRS and stereotactic radiation therapy systems, all of these systems utilize the same underlying principles: (1) patient immobilization, (2) targeting accuracy, (3) delivery of high doses of radiation, and (4) heterogeneous dose distribution with a steep dose gradient. Commercial SRS systems include Gamma Knife, which utilizes 201 radioactive cobalt sources positioned in a semispherical array, and Cyberknife, which utilizes robotics technology allowing the linear accelerator (LINAC) to track the patient position in real time during treatment. A standard LINAC can be equipped with cones attached to its head, allowing for circular collimation of the beam. The dose distribution from Gamma Knife, Cyberknife, or a standard LINAC equipped with cones is spherical, and thus treating nonspherically shaped targets requires the superposition of multiple spherical dose distributions. A LINAC equipped with multi-leaf collimators can also be used for SRS, which allows more conformal beam shaping. Also called radiation surgery, radiosurgery, and stereotaxic radiosurgery.
A type of external radiation therapy that uses special equipment to position the patient and precisely give a single large dose of radiation to a tumor. It is used to treat brain tumors and other brain disorders that cannot be treated by regular surgery. It is also being studied in the treatment of other types of cancer. Also called radiation surgery, radiosurgery, and stereotaxic radiosurgery.