Multiple-hit parameter estimation in monolithic detectors

William C.J. Hunter, Harrison H. Barrett, Robert S. Miyaoka, Tom K. Lewellen

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


We examine a maximum-a-priori (MAP) method for estimating the primary interaction position of gamma rays with multiple-interaction sites (hits) in a monolithic detector. In assessing the performance of a multiple-hit estimator over that of a conventional one-hit estimator, we consider a few different detector and readout configurations of a 50-mm-wide square LSO block. For this study, we use simulated data from SCOUT, a Monte-Carlo tool for photon tracking and modeling scintillation-camera output. With this tool, we determine estimate bias and variance for a multiple-hit estimator and compare these with similar metrics for a conventional ML estimator, which assumes full energy deposition in one hit. We also examine the effect of event filtering on these metrics; for this purpose, we use a likelihood threshold to reject signals that are not likely to have been produced under the assumed likelihood model. Depending on detector design, we observe a 1-12% improvement of intrinsic resolution for a 1-or-2-hit estimator as compared with a 1-hit estimator. We also observe improved differentiation of photopeak events using a 1-or-2-hit estimator as compared with the 1-hit estimator; more than 6% of photopeak events that were rejected by likelihood filtering for the 1-hit estimator were accurately identified as photopeak events and positioned without loss of resolution by a 1-or-2-hit estimator.

Original languageEnglish (US)
Title of host publication2011 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2011
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages6
ISBN (Print)9781467301183
StatePublished - 2011
Event2011 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2011 - Valencia, Spain
Duration: Oct 23 2011Oct 29 2011

Publication series

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


Other2011 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2011

ASJC Scopus subject areas

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


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