Single-photon spatial and energy resolution enhancement of a columnar CsI(Tl) / EMCCD gamma-camera using maximum-likelihood estimation

Brian W. Miller, H. Bradford Barber, Harrison H. Barrett, Irina Shestakova, Bipin Singh, Vivek V. Nagarkar

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

40 Scopus citations


We examined the spatial resolution of a columnar CsI(Tl), single-photon imaging system using an approach that estimates the interaction position to better than the spread of the light distribution. A columnar scintillator was directly coupled to a 512×512 electron multiplying CCD (EMCCD) camera (16 μm pixels) binned at 2×2 to sample at 32 μm pixels. Optical photons from gamma-ray/scintillator interactions are sampled over multiple pixels. Resultant images show clusters of signal at the original interaction site, clusters from Cs & I K x-rays up to several hundred microns away, and clusters from collimator K x-rays. Also evident are depth-of-interaction effects which result in a broadening of the light distribution. These effects result in a degradation of spatial and energy resolution. Cluster pixel data was processed to better estimate the interaction position within the initial interaction cluster. Anger (centroid) estimation of individual gamma-ray events yielded spatial resolutions better than 100 μm; a result previously achievable only with pixellated semiconductor detector arrays. After proper calibration, depth-of-interaction (DOI) effects are corrected by performing maximum-likelihood 3D position and energy estimation of individual gamma-ray interactions.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2006
Subtitle of host publicationPhysics of Medical Imaging
StatePublished - 2006
Externally publishedYes
EventMedical Imaging 2006: Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 12 2006Feb 16 2006

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume6142 II
ISSN (Print)1605-7422


OtherMedical Imaging 2006: Physics of Medical Imaging
Country/TerritoryUnited States
CitySan Diego, CA


  • CCD
  • Columnar CsI(Tl) scintillator
  • Gamma camera
  • Molecular imaging
  • Photon-Counting

ASJC Scopus subject areas

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


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