HeinzelCluster: accelerated reconstruction for FORE and OSEM3D

We have investigated two strategies to speedup reconstruction of data from our high resolution PET scanner (HRRT) on a dedicated cluster (7 nodes with 4 PIII Xeon@700 MHz, switched Fast Ethernet and Myrinet networking, Windows NT). With the first strategy, FORE/FOREJ and a fast 2D reconstruction method, we were able to reduce the 2D reconstruction time from 38 minutes to approx. 100 seconds. The second approach was to accelerate OSEM3D with a two-stage parallelization scheme resulting in a drop of reconstruction time from about 8 hours on one CPU to approx. 35 minutes for one core iteration.