arch-beerWeekly Reading |
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Eric is presenting... Optimizing Katsevich Image Reconstruction Algorithm on Multicore Processors Eric Fontaine and Hsien-Hsin S. Lee ICPADS'07 Paper (GT internal only) The Katsevich image reconstruction algorithm is the first theoretically exact cone beam image reconstruction algorithm for a helical scanning path in computed tomography (CT). However, it requires much more computation and memory than other CT algorithms. Fortunately, there are many opportunities for coarsegrained parallelism using multiple threads and fine-grained parallelism using SIMD units that can be exploited by emerging multicore processors. In this paper, we implemented and optimized Katsevich image reconstruction based on the previously proposed pi- interval method and cone beam cover method and parallelized them using OpenMP API and SIMD instructions. We also exploited symmetry in the backprojection stage. Our results show that reconstructing a 1024x1024x1024 image using 5120 512x128 projections on a dual-socket quad-core system took 23,798 seconds on our baseline and 642 seconds on our nal version, a more than 37 times speedup. Furthermore, by parallelizing the code with more threads we found that the scalability is eventually hinged by the limited front-side bus bandwidth. |