Tuesday, November 29, 2011

The Physics of X-Rays


What is an X-Ray?
            X-Rays are electromagnetic waves with a wavelength of .01 to 10 nanometers. They are generated in an X-Ray tube. X–Ray tubes work by shooting a stream of electrons at a piece of metal, usually tungsten. There is a magnetic field around the tungsten, which drastically slows down the electrons. Because energy is conserved, the kinetic energy of the electrons must be converted into another form when they are slowed down. The kinetic energy is converted into X-Rays, which are a form of radiant energy (the energy of electromagnetic waves).
 How X-Ray Images are Generated
            An X-Ray sensitive film is placed below a designated area of the body, and X-rays are shot at this area. Dense materials in the body, like bone, absorb or scatter the X-rays and do not let them reach the film in that area. This causes a white shadow to appear on the film that shows the shape of the bone. Less dense materials like muscle and fat allow most of the x-ray particles to pass through and reach the film, making the film dark in these areas.  - Post written by Sammy Kay-Green.


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