ABSTRACT
The application of medical linear accelerator to radiation oncology can be traced back to as early as the 1950s. In 1961, L. Leksell became the professor and the Chairman of Neurosurgery at Karolinska Institute in Sweden. He continued his research work on stereotactic radiosurgery (SRS). Due to its special characteristics, SRS imposes stringent physical and clinical requirements on implementation. The goal of frameless SRS is to achieve the inherent accuracy and precision of the frame-based stereotactic techniques with the guidance of high-resolution on-board image systems. Rapid advances in on-board imaging systems and the tremendous success of intracranial SRS encouraged investigators to extend the methodology of SRS to tumors in extra-cranial sites. SRS and stereotactic body radiation therapy involve small-field dosimetry. As small photon fields are utilized in SRS, accurate dosimetry is especially challenging. Film cutting is crucial in film dosimetry.
