Stereotactic Radiation Therapy (SRT) is a type of external radiation therapy that uses immobilisation systems to position the patient and precisely deliver radiation to a tumour. The total dose of radiation is divided into several smaller doses (or fractions) given over several days.

SRT is used to treat tumours of the head and neck. Stereotactic Body Radiation Therapy, also called Stereotactic Ablative Radiation Therapy (SABR) is used in the treatment of other types of cancer, such as lung or gastrointestinal cancer. What differentiates stereotactic from conventional radiotherapy is the precision with which it is delivered. The end result is the delivery of high doses of radiation with sub-millimetre accuracy.