Statistical decision making in emission tomography using emission-count posteriors

Arkadiusz Sitek, Joel S. Karp, Eugene Gualtieri, Sarah McQuaid, Mi Ae Park, Marie Foley Kijewski, Stephen C. Moore

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

1 Scopus citations


We present a new approach to decision making based on the concept of emission counts (EC), i.e., the number of events emitted per voxel during the scan. The approach allows direct computation of posterior probabilities of hypotheses defined in terms of EC, and is applicable to any type of emission tomographic list-mode projection data, e.g., SPECT, PET, or time-of-flight (TOF)-PET, as well as binned data which can be considered a special case of list-mode data. Conditional Bayesian (CB) decision theory utilizing values of the posterior probability of hypotheses as test statistics are used to derive decision rules. We demonstrate that the derived decision principle is equivalent to the likelihood-ratio ideal observer for binary hypothesis testing. We use data acquired in list-mode format for an anthropomorphic torso phantom using a lanthanum-bromide time-of-flight PET scanner to provide examples of application of EC-CB observer. For data-specific decisions, we demonstrate examples of multiple-hypotheses decision making. For imaging system evaluation, we define two regions of interest (ROIs) on the image, and two hypotheses, H1 and H2, that one ROI emitted on average at least r times more events than the other region. The posterior probabilities of H1 and H 2 are determined. ROC curves are constructed using 50 projection data sets (list-mode files), each including 16 million prompts, from which 25 data sets correspond to H1 and the other 25 to H2. The areas and partial areas under the ROC curves are used as figures of merit evaluating the performance of the LaBr3 PET system in discriminating between H1 and H2 with and without TOF information. Summary: A new optimal numerical observer which makes decisions based on posterior probability of emission counts is presented. The utility of the observer for hypothesis testing is demonstrated on TOF list-mode phantom data acquired on PENN LaPET scanner.

Original languageEnglish (US)
Title of host publication2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012
Number of pages4
StatePublished - 2012
Externally publishedYes
Event2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012 - Anaheim, CA, United States
Duration: Oct 29 2012Nov 3 2012

Publication series

NameIEEE Nuclear Science Symposium Conference Record
ISSN (Print)1095-7863


Other2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012
Country/TerritoryUnited States
CityAnaheim, CA

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging


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