HIGH-PERFORMANCE COMPUTING AND NETWORKING AS TOOLS FOR ACCURATE EMISSION COMPUTED-TOMOGRAPHY RECONSTRUCTION

It is well known that the quantitative potential of emission computed tomography (ECT) relies on the ability to compensate for resolution, a ttenuation and scatter effects. Reconstruction algorithms which are ab le to take these effects into account are highly demanding in terms of computing resources, The reported work aimed to investigate the use o f a parallel high-performance computing platform for ECT reconstructio n taking into account an accurate model of the acquisition of single-p hoton emission tomographic (SPET) data. An iterative algorithm with an accurate model of the variable system response was ported on the MIMD (Multiple Instruction Multiple Data) parallel architecture of a 64-no de Gray T3D massively parallel computer. The system was organized to m ake it easily accessible even from low-cost PC-based workstations thro ugh standard TCP/IP networking. A complete brain study of 30 (64 x 64) slices could be reconstructed from a set of 90 (64 x 64) projections with ten iterations of the conjugate gradients algorithm in 9 s, corre sponding to an actual speed-Lip factor of 135, This work demonstrated the possibility of exploiting remote high-performance computing and ne tworking resources from hospital sites by means of low-cost workstatio ns using standard communication protocols without particular problems for routine use. The achievable speed-up factors allow the assessment of the clinical benefit of advanced reconstruction techniques which re quire a heavy computational burden fur the compensation effects such a s variable spatial resolution, scatter and attenuation, The possibilit y of using the same software on the same hardware platform with data a cquired in different laboratories with various kinds of SPET instrumen tation is appealing for software quality control and for the evaluatio n of the clinical impact of the reconstruction methods.