tomography (tŏ-mog-răfi) n. the technique of rotating a radiation detector around the patient so that the image obtained gives additional three-dimensional information. In plain film tomography this produces an image of structures at a particular depth within the body, bringing them into sharp focus, while deliberately blurring structures above and below them. The visual record of this technique is called a tomogram. See also computerized tomography, positron emission tomography, SPECT scanning.

to·mog·ra·phy / təˈmägrəfē/ • n. a technique for displaying a representation of a cross section through a human body or other solid object using X-rays or ultrasound.DERIVATIVES: to·mo·graph·ic / ˌtōməˈgrafik/ adj.

tomography The use of X-rays to photograph a selected plane of a human body with other planes eliminated. The CT (computerized tomography) scanner is a ring-shaped X-ray machine that rotates through 180° around the horizontal patient, making numerous X-ray measurements every few degrees. The vast amount of information acquired is built into a three-dimensional image of the tissues under examination by the scanner's own computer. The patient is exposed to a dose of X-rays only some 20% of that used in a normal diagnostic X-ray.

tomography Any technique by which details of a subsurface plane can be represented graphically. See SEISMIC TOMOGRAPHY.

tomography Technique of X-ray photography in which details of only a single slice or plane of body tissue are shown.