Computer Tomography |
| In those days we called it a CAT scanner, or as likely “the
EMI” — at the time it was the only “scanner”.
Period. No chance of confusion there.
Computer Aided Tomography (CAT) later got shortened to Computer Tomography (CT). These devices (used to) consist of an X-Ray source and a sensor opposite each other and separated by enough space to fit a human body. An object is scanned by shooting a tightly focused beam of low intensity X-Rays through it from the source and sensing the strength of the remainder beam after it goes through the object. The whole contraption then rotates a little bit (say, one degree) and the process repeats. Once the scanner collects a bunch of these readings a computer munches on them and eventually it spits out a graphical representation of the “slice”. The object is then moved up a little bit (say, one centimeter) and the whole thing starts all over again. Once the procedure is done and all the slices have been computed, you have a stack of slices that can be used to “view” the insides of people without ever invading their bodies (’cept for the radiation, of course — but even that represents a much lower dose than is normally dispensed via traditional X-ray procedures). The name tomography refers to the fact that the scanner computes a “slice” of the scanned object, not just a flat image. Each slice really is a volumetric (tomo-) image (-graphy) made up of “voxels.” Each voxel represents a three-dimensional cube of the slice. |
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