Optimization of time-of-flight reconstruction on Philips GEMINI TF

  • Stefaan VandenbergheEmail author
  • Larry van Elmbt
  • Michel Guerchaft
  • Enrico Clementel
  • Jeroen Verhaeghe
  • Anne Bol
  • Ignace Lemahieu
  • Max Lonneux
Original Article



The aim of this study is to optimize different parameters in the time-of-flight (TOF) reconstruction for the Philips GEMINI TF. The use of TOF in iterative reconstruction introduces additional variables to be optimized compared to conventional PET reconstruction. The different parameters studied are the TOF kernel width, the kernel truncation (used to reduce reconstruction time) and the scatter correction method.


These parameters are optimized using measured phantom studies. All phantom studies were acquired with a very high number of counts to limit the effects of noise. A high number of iterations (33 subsets and 3 iterations) was used to reach convergence. The figures of merit are the uniformity in the background, the cold spot recovery and the hot spot contrast. As reference results we used the non-TOF reconstruction of the same data sets.


It is shown that contrast recovery loss can only be avoided if the kernel is extended to more than 3 standard deviations. To obtain uniform reconstructions the recommended scatter correction is TOF single scatter simulation (SSS). This also leads to improved cold spot recovery and hot spot contrast. While the daily measurements of the system show a timing resolution in the range of 590–600 ps, the optimal reconstructions are obtained with a TOF kernel full-width at half-maximum (FWHM) of 650–700 ps. The optimal kernel width seems to be less critical for the recovered contrast but has an important effect on the background uniformity. Using smaller or wider kernels results in a less uniform background and reduced hot and cold contrast recovery.


The different parameters studied have a large effect on the quantitative accuracy of the reconstructed images. The optimal settings from this study can be used as a guideline to make an objective comparison of the gains obtained with TOF PET versus PET reconstruction.


PET Time-of-flight Reconstruction 



The authors would like to thank Joel Karp, Suleman Surti and Margaret Daube-Witherspoon from UPENN and Amy Perkins from Philips Research USA for useful suggestions on parameter selection in the commercial software


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Stefaan Vandenberghe
    • 1
    Email author
  • Larry van Elmbt
    • 3
  • Michel Guerchaft
    • 2
  • Enrico Clementel
    • 1
  • Jeroen Verhaeghe
    • 1
  • Anne Bol
    • 3
  • Ignace Lemahieu
    • 1
  • Max Lonneux
    • 3
  1. 1.MEDISIP Research Group ELIS-IBBT-IBITECHGhent University, University Hospital GhentGhentBelgium
  2. 2.Philips Medical Systems BeneluxBrusselsBelgium
  3. 3.Center for Molecular Imaging and Experimental RadiotherapyUniversite Catholique de LouvainBrusselsBelgium

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