Biomedical Engineering Reference
In-Depth Information
FIGURE 15.7 Overview of the three x-ray techniques used to obtain “medical images.” (a) A conventional x-ray
picture is made by having the x-rays diverge from a source, pass through the body, and then fall on a sheet of photo-
graphic film. (b) A tomogram is made by having the x-ray source move in one direction during the exposure and the
film in the other direction. In the projected image, only one plane in the body remains stationary with respect to the
moving film. In the picture, all other planes in the body are blurred. (c) In computerized tomography, a reconstruction
fromprojections is made bymounting the x-ray source and an x-ray detector on a yoke andmoving thempast the body.
The yoke is also rotated through a series of angles around the body. Data recorded by the detector are processed by a
special computer algorithm or program. The computer generates a picture on a cathode-ray screen.
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