<P> An X-ray tube is a vacuum tube that converts electrical input power into X-rays . X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered on November 8, 1895, by the German physicist Wilhelm Conrad Röntgen . The availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation . In contrast to other sources of ionizing radiation, X-rays are only produced as long as the X-ray tube is energized . X-ray tubes are also used in CT scanners, airport luggage scanners, X-ray crystallography, material and structure analysis, and for industrial inspection . </P> <Ul> <Li> A: Anode </Li> <Li> C: cathode </Li> <Li> T: Anode target </Li> <Li> W: X-ray window </Li> </Ul>

What kind of tube is used to produce x rays