X-Ray diagnostic system comprising means for the fixed specification of exposure time, x-ray tube voltage, and mAs-product

An x-ray diagnostic system comprising an x-ray tube for supplying x-ray energy at a film plane, supply means for supplying x-ray tube voltage to said x-ray tube, means for the fixed specification of the exposure time of an x-ray photograph, and adjustment means for selecting the x-ray tube voltage and the mAs-product, characterized in that an x-ray tube current control loop for controlling the x-ray tube current is present which controls the x-ray tube current on the basis of the fixed exposure time and the selected mAs-product, said x-ray tube current control loop comprising actual x-ray tube current sensing means for sensing the actual value of x-ray tube current, x-ray tube current setpoint means controlled in accordance with the fixed specification of the exposure time, and being operable in conjunction with the adjustment means for selecting mAs-product, to provide a corresponding setpoint value of x-ray tube current, and x-ray tube current control means for controlling the x-ray tube current and responsive to deviations of the actual x-ray tube current as sensed by said actual x-ray tube current sensing means, from the setpoint value of x-ray tube current as provided by said x-ray tube current setpoint means, to tend to maintain the actual value of x-ray tube current at said setpoint value, said supply means comprising a high voltage transformer (6) having a primary circuit, and said x-ray tube current control loop comprising a keying circuit (23) for controlling the x-ray tube current, arranged in the primary circuit of the high voltage transformer (7).