ABSTRACT
Medical imaging techniques have been used since the discovery of x-rays by Roentgen in 1895. Techniques other than simple planar radiographs have become available during the last 50 years. These include, in historical order, radioisotope (NM) images, ultrasound (US) images, computed tomography (CT) images and magnetic resonance (MR) images. In particular, the past two decades have seen fairly dramatic developments in all these technologies. Although x-ray planar images and planar isotope images still form the backbone of radiology and nuclear medicine the trend is steadily towards the production of tomographic images, images of slices through a three-dimensional object, or even full three-dimensional images. Ultrasound images have always been tomographic images, as have MR images. The invention of computed tomography allowed tomographic x-ray images to be generated, as did the application of similar techniques to radioisotope imaging, although in fact the generation of radioisotope tomographic images predated CT by a few years.
