The German physicist Wilhelm Roentgen discovered X-rays in 1895. "X-ray beams can pass through your body, but they are absorbed in different amounts depending on the density of the material they pass through," according to the Mayo Clinic. Physicians have used X-rays, also known as medical imaging, since 1896, and they continue to be their most popular diagnostic method. The use of X-rays proves helpful in other areas as well, including airport security and space studies
The medical community uses X-rays to examine several parts of the body and to treat conditions. "Imaging with X-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body," according to the Radiological Society of North America. The denser the material, the more X-rays it will absorb and later appear white in the picture. For example, bones and teeth, which are both dense, show up white, while lungs that contain lots of air show up as black. Muscle and fat appear gray. Skin absorbs few X-rays, making it appear transparent and enabling the dentist to get a good view of a patient's teeth. Because metal absorbs the most X-rays, the dentist easily spots fillings in teeth. Physicians use X-rays to detect broken bones, joint dislocations, spinal fusions, abnormal bone growths, arthritis and bony changes seen in metabolic conditions. They also use it to detect swallowed objects, to examine breast tissue, to evaluate infections and cancerous conditions in the chest, to highlight the circulatory system and to check for enlarged hearts. Doctors treat certain cancers with a high frequency X-ray in a procedure called radiotherapy.
Before you can board an aircraft, your luggage has to pass through a scanner so that airport personnel can verify what objects you will bring on board. The scanner uses a specialized X-ray frequency for this purpose: "It must be high enough to penetrate hard-shell baggage, but low enough to prevent the accidental exposure of camera film," explains the general information site Medical Discoveries.
Astronomers use X-ray detectors to study objects in space. These objects include regular and neutron stars, black holes, binary star systems, supernova remnants, the sun and some comets. Because X-rays cannot penetrate the earth's atmosphere, scientists have to put X-ray detectors and telescopes in orbiting satellites. "In astronomy, things that emit X-rays (for example, black holes) are like the dentist's X-ray machine, and the detector on the satellite is like the X-ray film," according to National Aeronautics and Space Administration.