Stereotactic radiation therapy is a type of external radiation therapy that uses special equipment to position the patient and precisely deliver radiation to a tumor. The total dose of radiation is divided into several smaller doses given over several days. Stereotacticradiation therapy is used to treat brain tumors and other brain disorders. It is also being studied in the treatment of other types of cancer, such as lung cancer. Also called stereotactic external-beam radiation therapy and stereotaxic radiation therapy. What differentiates Stereotactic from conventional radiotherapy is the precision with which it is delivered. There are multiple systems available, some of which use specially designed frames which physically attach to the patient's skull while newer more advanced techniques use thermoplastic masks and highly accurate imaging systems to locate the patient. The end result is the delivery of high doses of radiation with sub-millimetre accuracy.