How does an x-ray work?

Plain film radiography unifies principles of photography, anatomy, and x-ray production. X-rays are produced by applying an electric potential across a tube, where electrons are "boiled off" a cathode filament. This electron stream strikes a rotating, positively charged target, the anode. The spinning sound one can often hear during the x-ray study is the rotation of the anode. When the electrons slow down, and when they strike the target, x-rays are produced. A person cannot feel, taste, or see the x-rays as they pass through the body.

The amount and type of x-rays are selected by the operator, usually the radiologic technologist (RT), who adjusts exposure and beam quality. Pre-set ranges are based on the patient thickness, the tissue being imaged, and the desired image contrast. Because motion of the lungs and diaphragm blurs the image -- much as when a photographic subject moves during the snap -- patients are usually asked to hold their breath during the exposure.

The final product is stored on a piece of film, the radiograph. The radiographs are read by the radiologist, a physician specially trained to interpret the images. The x-ray diagnosis is transcribed into a written report and sent to the requesting physician.

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