1996 Volume 8 Issue 1 Pages 77-81
A linac system (Mitsubishi ML15MV) was modified in the following manner so as to enable stereotatactic rediotherapy. A small CCD (charge-coupled device) video-camera, beam's eye monitor, is mounted in the gantry of the linac at the place optically identical to the linac x-ray source.
Standard parts of the Leksell stereotactic system were used for localizing the target point on the patient's head. A positioning device-a target pointer consisting of two sets of cross hairsis attached, for positioning purpose, to the arc of the stereotactic system. The target pointer always indicates the center of the arc, regardless of the direction in which the target pointer or the arc is oriented. The monitor system and the target pointer are used together to maintain the center of the arc on the isocenter of the linac. This method enables us to perform precise positioning without having to use a special head-supporting stand.
