A Statistical DOI Estimation Algorithm for a SiPM-Based Clinical SPECT Insert

Ilenia DrAdda, Ashley J. Morahan, Marco Carminati, Kjell Erlandsson, Michael Ljungberg, Brian F. Hutton, Carlo Fiorini

Research output: Contribution to journalArticlepeer-review


A prototype clinical brain SPECT insert has been designed for use in simultaneous SPECT/MRI. The system utilises novel slit-slat collimators which, like pinhole collimators, suffers from parallax errors due to the large incident angle of photons. A statistical algorithm has been developed to determine the depth-of-interaction (DOI) with a view to improving image performance. The importance of DOI correction was demonstrated using Monte Carlo simulation. This simulation also indicated that 4 DOI layers (3×1.5 mm+3.5 mm) may be sufficient. The improvement in event localisation was demonstrated on a single detector before implementing the algorithm on the full clinical prototype where some limitations in event localisation in layers close to the readout plane were observed. Nevertheless DOI enabled the rejection of poorly localised events with improved resolution in reconstructed line sources.

Original languageEnglish
Pages (from-to)771-777
JournalIEEE Transactions on Radiation and Plasma Medical Sciences
Issue number7
Early online date2022
Publication statusPublished - 2022

Subject classification (UKÄ)

  • Radiology, Nuclear Medicine and Medical Imaging

Free keywords

  • Biomedical imaging
  • Calibration
  • Collimators
  • depth-of-interaction
  • Detectors
  • event localisation.
  • Image reconstruction
  • Plasmas
  • Single photon emission computed tomography


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