Implementation of sensitivity and resolution modeling for SPECT with cone-beam collimator

A. Krol, V. R. Kunniyur, W. Lee, K. R. Gangal, I. L. Coman, E. D. Lipson, D. A. Karczewski, F. D. Thomas, D. H. Feiglin

Research output: Contribution to journalConference Articlepeer-review


We implemented a fully-3D ordered-subsets expectation-maximization (OSEM) algorithm with attenuation compensation, distance-dependent blurring (DDB), and sensitivity modeling for SPECT performed with a cone-beam collimator (CBC). The experimentally obtained detector response to point sources across FOV was fitted to a two-dimensional Gaussian function with its width (FWHM) varying linearly with the source-to-detector distance and with very weak sensitivity dependence on the emission angle. We obtained CBC SPECT scans of a physical point-source phantom, a Defrise phantom, and a female patient, and we investigated performance of our algorithm. To correctly simulate DDB and sensitivity, a blurring kernel with a radius of up to 10 elements had to be used for a 128×128 acquisition matrix, and volumetric ray tracing rather than line-element-based ray tracing has to be implemented. In the point-source phantom reconstruction we evaluated the uniformity of FWHM for the radial, tangential and longitudinal directions, and sensitivity vs. distance. An isotropic and stationary resolution was obtained at any location by OSEM with DDB and sensitivity modeling, only when volumetric ray tracing was used. We analyzed axial and transaxial profiles obtained for the Defrise phantom and evaluated the reconstructed breast SPECT patient images. The proposed fully-3D OSEM reconstruction algorithm with DBB and sensitivity modeling, and attenuation compensation with volumetric rays tracing is efficient and effective with significant resolution and sensitivity recovery.

Original languageEnglish (US)
Article number249
Pages (from-to)2130-2135
Number of pages6
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Issue numberIII
StatePublished - 2005
EventMedical Imaging 2005 - Image Processing - San Diego, CA, United States
Duration: Feb 13 2005Feb 17 2005


  • Cone-beam SPECT
  • Ray trace
  • Resolution modeling
  • Sensitivity modeling

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging
  • Biomaterials


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