The problem of reconstructing cross-sections from their projections, using Fourier transform processing, is considered in detail and is related to problems in medical tomography. A number of equations relating cross-sections to their projections are derived, and are used as the bases for algorithms which enable cross-sections to be reconstructed from a finite number of projections. Results of computations on analytically derived and radiographically measured projections demonstrate the usefulness of these techniques.

A proposal for a new type of transverse tomographic system is described. It is demonstrated that images of cross­ sections may be restored from tomograms produced using this system, by the use of both optical and digital processing techniques.

Image reconstruction techniques using Fourier transforms are shown to be of use for reconstructing three-dimensional radio-isotope distributions, from scintigraphic projections measured with a gamma camera.