Abstract: An exemplary embodiment comprises a patient support, an x-ray tube supplied by an x-ray generator, an x-ray image intensifier with a series connected television chain, a control loop for the controlling the mean image brightness, a syringe for contrast medium injection, and a program memory for storing several radiographic exposure programs. A time measuring device is present which is started by the syringe and is stopped by an evaluation unit when the mean image brightness varies to a predetermined extent. A computer calculates the contrast medium velocity from the measured time and the distance (x) between the injection location and the measuring location. On the basis of the calculated contrast medium velocity, an optimum program calculation, or program selection, respectively, is possible.

Abstract: In an exemplary embodiment in order to establish the desired relationship between x-ray tube voltage and x-ray tube current, at least one series resistance is connected in the power path between the mains and the x-ray tube. A switching device for by-passing the series resistance is present which is controlled by a comparator for the actual value and setpoint value of the x-ray tube voltage in such a fashion that the series resistance is by-passed at the commencement of a radiograph as long as the actual value is smaller than the setpoint value.