BY

In preparing this paper I realised that I would be speaking to a general audience and have therefore included a description of computed tomography (CT) and some of my early experiments that led up to the develop-ment of the new technique. I have concluded with an overall picture of the CT scene and of projected developments in both CT and other types of systems, such as Nuclear Magnetic Resonance (NMR). Although it is barely 8 years since the first brain scanner was constructed, computed tomography is now relatively widely used and has been extensively demonstrated. At the present time this new system is operating in some 1000 hospitals throughout the world. The technique has succesful-ly overcome many of the limitations which are inherent in conventional Xray technology. When we consider the capabilities of conventional X-ray methods, three main limitations become obvious. Firstly, it is impossible to display within the framework of a two-dimensional X-ray picture all the informatio