Patent ID: 7742571

Claim:
A grid control system for eliminating soft radiation emitted from an x-ray tube by controlling the voltage though the x-ray tube, the grid control system comprising: an x-ray tube having an anode, a cathode, and a grid; a source of first pulsed high voltage of a magnitude, a duration and a first frequency connected across the cathode and the anode so that a first pulsed high voltage is continuously applied to the x-ray tube for the duration of the pulse; a second source of pulsed high voltage connected to the grid, the second pulsed high voltage being of a second frequency and providing a voltage of substantially the same magnitude as the voltage provided by the source of first pulsed high voltage and being of a polarity that reduces the magnitude of the first pulsed high voltage and being of a frequency that is higher than the first frequency, so that voltage between the cathode and the anode is switched by the voltage applied to the grid by the second source of pulsed high voltage while first pulsed high voltage is continuously applied to the x-ray tube.