One of the most important characteristic of X-rays is their ionizing power, which depends upon their wavelength. The capacity of monochromatic X-rays to ionize is directly proportional to their energy. This property provides a method for measuring the energy of X-rays. When X-rays are passed through an ionization chamber an electric current is produced that is proportional to the energy of the incident beam. In addition to ionization chambers, more sensitive medical xray equipment , such as the Geiger-Mьller counter and the scintillation counter, can measure the energy of X-rays on the basis of ionization. In addition, the path of X-rays, by virtue of their capacity to ionize, can be made visible in a cloud or bubble chamber. X-ray photographs, called radiographs, and fluoroscopy are used extensively in medicine as diagnostic tools. In radiotherapy, medical xray equipment is used to treat certain diseases, notably cancer, by exposing tumours to X radiation. The value of radiographs for diagnostic purposes is a consequence of the penetrating properties of X-rays. Within a few years of their discovery, X-rays were being used to locate foreign bodies, such as bullets, within the human body. With the development of improved X-ray techniques, minute differences in tissues were revealed by radiographs, and many pathological conditions could be diagnosed by non ionizing radiation means. X-rays provided the most important single method of diagnosing tuberculosis when that disease was prevalent. The routine use of X-ray diagnosis has in fact been discouraged in recent years as of questionable usefulness. A recent medical xray equipment, used without dyes, offers clear views of any part of the anatomy, including soft organ tissues. Called the body scanner, or computerized axial tomography (CAT or CT) scanner, it rotates 180° around a patient's body, sending out a pencil-thin X-ray beam at 160 different points. Crystals positioned at the opposite points of the beam pick up and record the absorption rates of the varying thicknesses of tissue and bone. These data are then relayed to a computer that turns the information into a picture on a screen. Using the same dosage of radiation as that of the conventional X-ray machine, an entire "slice" of the body is made visible with about 100 times more clarity. The scanner of non ionizing radiation was invented in 1972 by the British electronics engineer Godfrey Hounsfield, and was in general use by 1979. Medical xray equipment emits lot of energy and can make affected materials become ionized or charged. They can even damage DNA cells in the living matter. Nevertheless, if used carefully, the advantages of medical xray equipment far outweigh its disadvantages. Non-ionizing radiation may be defined as sonic, ultrasonic or electromagnetic radiation together with ELF (extremely low frequency coming from powerlines and other sources) which doesn't "ionizes atoms". "To ionize an atom" means to eliminate the electron from the atom. True non ionizing radiation has enough energy only for stimulating rotational and vibrational motions of molecules. So, the radiation is able to increase either molecules' random motion or their average kinetic energy. The kinetic and molecular theory of matter tells that the motion is nothing but heat, and the increase of the average kinetic energy is temperature.