High-resolution hybrid digital-optical processor for transaxial tomography

A hybrid digital-optical processor for reconstructing a 2-dimensional scalar field from its 1-dimensional projections will be presented. This processor represents a further development in a continuing effort to incorporate and utilize the power of optical data processing in x-ray computed tomography. The processor to be described operates on a data set recorded on x-ray film. The reconstruction of the field from its projection data is obtained via the filtered back-projection algorithm. Specifically, the time consuming operations of filtering and back-projection are done optically. Final addition and subtraction operations are done in digital hardware, with the final image residing in a digital memory. Sophisticated image enhancement operations are then possible with computer back-up. The interface between the optical and digital hardware is simple video. This particular processor has the very attractive feature that full digital resolution can in principle be obtained over any desired area of the reconstructed image so that the final system should be limited by the x-ray detector, in this case film, which inherently has a much greater resolution capability than the discrete detector arrays found in conventional CT scanners.