[Bases, technic and expressiveness of computer tomography. Indications and efficiency].

The developments of reconstruction mathematics, computer technology and X-ray detectors were prerequisite to the invention of computer tomography. Essential progress was made leading to the development of the currently used third and fourth generation scanners. The use of CT has greatly influenced diagnostic imaging and therapy planning. The main advantages of CT are the demonstration of the third dimension, the differentiation of very minor density differences and non-invasiveness. In spite of the high costs of CT equipment and maintenance, an overall reduction of cost was achieved by decreasing the number of diagnostic procedures and reducing the time between the beginning of illness and therapy.