Abstract for presentation at 38th Annual Scientific Meeting of the Australian and New Zealand Society of Nuclear Medicine 2008

Systematic Validation of the Single Scatter Simulation Protocol on Philips Gemini PET/CT

  • Dr Sylvia Gong, Centre for P.E.T., Austin Hospital, Melbourne, Australia
  • Dr Graeme O'Keefe, Centre for P.E.T., Austin Hospital, Melbourne, Australia
  • Dr Aurora Poon, Centre for P.E.T., Austin Hospital, Melbourne, Australia
  • Dr Sam Berlangieri, Australia
  • Kunthi Pathmaraj, Centre for P.E.T., Austin Hospital, Melbourne, Australia
  • Ms Jessica Welch, Australia
  • Jason Bradley, Centre for P.E.T., Austin Hospital, Melbourne, Australia
  • Prof Andrew Scott, Centre for P.E.T., Austin Hospital, Melbourne, Australia

    • Objective: Single scatter simulation (SSS) promises to provide more accurate scatter correction for 3D PET than background subtraction (BGS) method. The study investigates image artifacts and SUV discrepancy observed in SSS images. This leads to the systematic validation of the protocol parameters for its optimal implementation.
    Methods: PET/CT/Cs scans of F-18 lung phantom with hot and cold spheres, F-18 flood and Ge-68 solid uniformity phantoms were acquired on a Philips Gemini PET/CT individually. Phantom images were reconstructed using various protocol parameters and assessed quantitatively. Images of 20 consecutive patients and 10 large patients (>100kg) were processed in the same way and assessed blindly by two physicians.
    Results: SUV was 20±3% less in images corrected with SSS comparing to BGS. The overall quality and contrast rating indices are 3.7±0.48 and 3.9±0.38 for SSS images, 3.8±0.32 and 3.6±0.52 for BGS images respectively (score 4 indicates best and 1 the worst). The implementation of SSS using small sinogram with 1 iteration of 2D RAMLA achieved similar scatter estimation to the protocol using big sinogram with 2 iterations of 3D RAMLA but half of its total processing time (3.7±0.6 mins/frame).
    Conclusion: SSS offers a feasible alternative to BGS within acceptable time for clinical whole-body scans. Scatter scaling and subtraction must be performed prior to 3D reconstruction with attenuation correction for accurate compensation. To confirm clinical and research scans assessed within a multi-scanner PET centre having a known degree of SUV consistency, calibrations need be performed correspondingly to the adopted correction and reconstruction protocols.

    Conference Organiser - ICMS Pty Ltd