[Tomodensitometry: current technique and perspectives]

The inventors of computed tomography were rewarded by the Nobel Prize for Medicine in 1979. This apparatus, now used routinely, is based on the physical principle of attenuation of x-rays combined with computerised calculation to generate a tomographic image of the human body. This article describes the components of computed tomography, the mode of acquisition, calculation and image reconstruction and the criteria of image quality and artefacts. Continuous rotation of the x-ray tube, now available on the latest machines, allows rapid 3D acquisition of raw data, largely eliminating movement artefacts, particularly those related to respiration. It is also possible to reconstitute images in a different plane from the plane of acquisition and to obtain 3D representations of the volume studied. The advantages and disadvantages of this recent technique are discussed.