An imaging technique that produces a cross-sectional image (“slice”) of an organ or part of the body. Most tomography today is performed using CT scanning and MRI, which produce accurate and detailed images.
A technique using X-RAYS or ULTRASOUND to build up a focused image of a ‘slice’ through the body at a given level. By producing a series of such slices at di?erent depths, a three-dimensional image of the body structures can be built up.
n. a technique used to produce an image (tomogram) of structures at a particular depth within the body by bringing them into sharp focus while deliberately blurring structures above and below them. In plain film tomography the source of X-rays and the photographic film are moved around the patient to produce a single ‘slice’ at a time. By contrast, multiple slices are produced in *computerized tomography (CT), which uses multiple radiation detectors so that the images can be stacked up to give additional three-dimensional information. See also dental pantomogram; positron emission tomography; SPECT scanning.
(CT) a form of X-ray examination in which the X-ray source and detector (CT scanner) rotate around the object to be scanned and the information obtained can be used to produce cross-sectional images (see cross-sectional imaging) by computer (a CT scan). A higher radiation dose is received by the patient than with some conventional X-ray techniques, but the diagnostic information obtained is far greater and should outweigh the increased risk. CT scanning can be used for all parts of the body. The data obtained can be used to construct three-dimensional images of structures of interest. See also multidetector computerized tomography; spiral CT scanning.... computerized tomography
(MDCT) a development of *spiral CT scanning that uses more than one array of detectors opposite the X-ray tube, so that more tissue can be included, with thinner cuts, in a single rotation of the machine. This is particularly important for three-dimensional reconstruction of tissues. It also allows volumetric scanning or *isotropic imaging, which are best achieved when the thickness of the slice is similar to the size resolution of the detectors in the other two planes. Modern CT scanners are now usually equipped with between 16 and 640 detector arrays. The technique is particularly valuable for imaging fast-moving structures, such as the heart.... multidetector computerized tomography
(OCT) a class of optical tomographic techniques that allows extremely high-quality micrometre-resolution three-dimensional images to be obtained from within optical scattering media (e.g. biological tissue). OCT is proving valuable in ophthalmology, for noninvasive imaging of the ocular structures, and in cardiology for visualizing the interior of coronary arteries using a specialized *catheter. See also spectral domain optical coherence tomography.... optical coherence tomography
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