System and method for automatic control of processes or application, such as the activation or deactivation of a radiation source for medical purposes. The system comprises an operator tracking system arranged to determine the gesture/posture of a user, an evaluation device arranged to evaluate the determined gesture/posture, and an enabling device arranged to enable and disable the radiation source in response to an output of the evaluation device. The operator tracking system may use a gazing direction analysis that may be based on the output of an eye tracking system, or an emitter-receiver arrangement for a directed signal.