Acceleration of SimSET Photon History Generation

Robert L. Harrison, Somasekhar Dhavala, Prasanth N. Kumar, Yiping Shao, Ravindra Manjeshwar, Tom K. Lewellen, Floris P. Jansen

Research output: Chapter in Book/Report/Conference proceedingConference contribution

17 Scopus citations


SimSET (a Simulation System for Emission Tomography) is widely used for studying PET and SPECT. As emission tomography simulation has become a more mature field, the scope of the research being performed, and thus the complexity of the simulations required, has grown immensely. Researchers are increasingly interested in clinically realistic simulations, and in some cases need hundreds or thousands of realizations. To meet these needs, we are investigating methods for accelerating SimSET. SimSET has always incorporated importance sampling (IS). Early studies showed the use of IS led to efficiencies 10-100 times greater than those achieved using analog (conventional) simulation. However, as the simulation became increasingly realistic the assumptions underlying the IS algorithms were violated. The efficiency improvement fell as low as a factor of two for some simulations. We are addressing this loss of efficiency by updating SimSET's algorithms, code optimization, and by modifying the software to run on multiple processors. We hope, with the new IS, to be able to simulate a 3D PET FDG brain scan (300 million detected events) in 3 hours on a 2 GHz processor. This would be a factor of 20 speedup over the currently distributed software. To date we achieved a factor of 1.5-3 speedup by changing three algorithms and doing some code optimization. We have several more algorithm improvements and another round of code optimization planned. We have made significant progress on parallel processing. Prototype code based on the last distributed version of SimSET achieved a speedup very close to the number of processors used. The new software also allows for multiple realizations of the same simulation to be automatically generated on multiple processors.

Original languageEnglish (US)
Title of host publicationIEEE Nuclear Science Symposium and Medical Imaging Conference
EditorsS. Metzler
Number of pages4
StatePublished - Dec 1 2002
Event2002 IEEE Nuclear Science Symposium Conference Record - Norfolk, VA, United States
Duration: Nov 10 2002Nov 16 2002


Other2002 IEEE Nuclear Science Symposium Conference Record
Country/TerritoryUnited States
CityNorfolk, VA

ASJC Scopus subject areas

  • Computer Vision and Pattern Recognition
  • Industrial and Manufacturing Engineering


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