Dose Characteristics of Stereotactic Radiosurgery in High Energy Linear Accelerator Photon Beam

Choi, Tae Jin; Kim, Ok Bae

Abstract

Three-dimensional dose calculations based on CT images are fundamental to stereotactic radiosurgery for small intracranial tumor. In our stereotactic radiosurgery program, irradiations have been performed using the 6 MV photon beam of linear accelerator after stereotactic CT investigations of the target center through the beam's-eye view and the coordinates of BRW frame converted to that of radiosurgery. Also we can describe the tumor diameter and the shape in three dimensional configuration. Non-coplanar irradiation technique was developed that it consists of a combination of a moving field with a gantry angle of 140degree, and a horizontal couch angle of 200degreearound the isocenter In this radiosurgery technique, we provide the patient head setup in the base-ring holder and rotate around body axis. The total gantry moving range shows angle of 2520 degrees via two different types of gantry movement in a plane perpendicular to the axis of patient. The 3-D isodose cuties overlapped to the tumor contours in screen and analytic dose profiles in calculation area were provided to calculate the thickness of 80% of tumor center dose to 20% of that. Furtheremore we provided the 3-D dose profiles in entire calculation plane. In this experiments, measured isodose cuties in phantom irradiation have shown very similar to that of computer generations.