Stereotactic radiosurgery (SRS) is a form of radiotherapy that employs stereotactic techniques. 'Stereotactic' refers to the utilization of a system of 3-D coordinates to ensure that treatment is focussed in a highly precise way which allows smaller margins and higher doses per treatment 1. Stereotactic radiosurgery involves a smaller number of treatments (typically just one) compared to conventional radiotherapy treatment schedules which require up to thirty treatments (a.k.a. fractions).
The term "stereotactic radiosurgery" is reserved for treatments to the brain or spine, while stereotactic body radiotherapy (SBRT or SABR) refers to stereotactic treatment elsewhere in the body 1,2.
Stereotactic treatments are delivered either with IMRT linear accelerators (requiring more advanced patient immobilization or image guidance) or dedicated systems such as Gamma Knife or CyberKnife.