Analog Reconstruction Methods for Transaxial Tomography

Transaxial tomography is a radiographic technique that provides an image of an isolated two-dimensional section of a three-dimensional object The basic principles of this technique are reviewed here and the equivalence of various mathematical formulations is shown. The properties of the resulting image for various filter functions are described and the limitations imposed by the quantum statistics of the radiation source are briefly discussed. Then various optical approaches to implementing the reconstruction process are described. The distortions arising from the use of a diverging beam of X-rays are detailed, and some simple modifications of the optical systems are shown to substantially eliminate them.