Grid controlled x-ray tube switching time: implications for rapid exposure control.

The transient response properties of a conventional grid controlled x-ray source and the implications for rapid exposure control are studied. The use of a cathode cable with a length of only 1 m to connect the x-ray tube and the grid control electronics results in a switching time of 19 microseconds. The phototiming artifacts from the delayed radiation delivered during this transition time can be severe for short pulses. An analog correction technique that anticipates the magnitude of the delayed radiation is used to overcome this limitation and allows accurate phototiming over a wide range of pulse widths ranging down to 20 microseconds.