[Fully automatical control of patient positioning--a new technique leading to exact and safe radiation therapy (author's transl)]

Any motion of the patient causing a displacement of the target volume or an immediate mechanical danger in the course of radiation therapy must be prevented. A new possibility for individual objective monitoring of patient movements, fully automatical, can be presented. Every significant displacement is releasing alarm and is detectable instantaneously. Normal respiratory movements or even the motion of the gantry do not cause a wrong alarm. Important displacements will interrupt the irradiation. Mechanical hazards to the patient thus are almost impossible. First experiences are reported.