New methods of imaging in diagnostic radiology Sylvanus Thompson Memorial Lecture.

A brief history of the recent developments in computer-assisted tomography (CAT) is presented. The development of whole-body scanners from the basic brain scanner, the trend towards higher-speed scanners using multiple detectors in a fan-type geometry, and some of the unsolved problems related to CAT scanners are discussed, as well as the potential use of whole-body scanning in radiotherapy treatment planning and in radiobiology. A review of recent developments in electrostatic imaging is presented and a new method of imaging called ionography is described in detail. It is shown how a single exposure can be used to produce a number of copies, each with a different amount of edge contrast, under the control of the radiologist. Further, it is shown how this can be done using a closed system so that the ionography chamber never needs to be opened. Some of the recent commercial developments in this field are described. It is suggested that in the future radiology departments may be replaced by departments of imaging, which will include all ways of obtaining diagnostic information and where such a department would be problem oriented rather than technique oriented. The need for basic scientific support by a medical physics and engineering group in such a department is emphasized.