Historical experiments predating commercially available computed tomography.

Abstract

Computed tomography (CT) was a revolution in radiology. Commercially available CT scanners appeared in 1972, a joint effort between the EMI Company, Atkinson Morley's Hospital, London and the Department of Health and Social Security (DHSS). The name of Sir Godfrey Hounsfield will always be associated with these developments. Like most developments in science the breakthrough came by standing on the shoulders of giants and many experiments can, with the curious wisdom of hindsight, be considered precursors to CT. Gabriel Frank's patent in 1940 showed apparatus for back-projection CT and Takahashi developed equipment in the 1940s for reconstructing from a sinogram; in both cases using an optical "computer". A medical CT scanner was reportedly constructed in 1957 in Kiev. Transmission CT was performed by Kuhl in 1965. Cormack built an experimental scanner in 1963. Oldendorf identified what was needed for successful CT as early as 1960. Throughout the 1960s a host of independent workers were busy on the mathematical problems of reconstructing from projections with both medical scanning and non-medical applications in mind. Experiments in early emission tomography influenced the development of CT. With imagination one can even see how close "classical" tomography, as started even before 1920, came to the realization of CT. The pioneering British radiographer Watson stands out from a galaxy of inventors. The lecture at Radiology and Oncology '91 in Brighton was a thumbnail sketch of the origins of radiological CT. A fuller story is told elsewhere (Webb, 1990).