Published online by Cambridge University Press: 26 July 2017
There are at present two techniques that use X-rays to show internal structures, both are in common use in medicine. The first technique is essentially a photographic method (for extensive description see Quinn and Sigl, 1980). The second (Cat scan or Computer Tomography) computes a section from many pictures taken by a thin, fan shaped X-ray beam. X-rays are a form of electromagnetic radiation with a wave length 10,000 times smaller, and energy 10,000 times greater, than visible light. They are generated in a high-vacuum tube where electrons are produced by a heated cathode and are shot at high electromotive force (30 to over 100 kilovolts) at the anode where most of the energy is converted to heat; only a small fraction is given off as X-radiation.