Cache-optimized implementation of the filtered backprojection algorithm on a digital signal processor

The reconstruction of an image from its projections through filtered backprojection is not new and has gained popularity since its application on computerized tomography (CT) for medical imaging. However, the number of projections to reconstruct a single image can be in the thousands. Thus, significant computational power is required. Today's digital signal processors (DSPs) offer an alternative for implementations of a backprojector to process large amounts of data. We demonstrate an implementation in a fixed-point DSP This implementation is optimized for cache memoty to reduce CPU stalls, and we achieved up to 99.6% of effective CPU cycles. With a DSP running at 1 GHz, an image of 1200 X 1200 pixels can be reconstructed from 180 projections in 1 s. (c) 2007 SPIE and IS&T.