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6 March 2008Assessment of scanning model observers with hybrid SPECT images
The purpose of this work was to test procedures for applying scanning model observers in order to predict human-observer
lesion-detection performance with hybrid images. Hybrid images consist of clinical backgrounds with
simulated abnormalities. The basis for this investigation was detection and localization of solitary pulmonary
nodules (SPN) in SPECT lung images, and our overall goal has been to determine the extent to which detection
of SPN could be improved by proper modeling of the acquisition physics during the iterative reconstruction
process. Towards this end, we conducted human-observer localization ROC (LROC) studies to optimize the
number of iterations and the postfiltering of four rescaled block-iterative (RBI) reconstruction strategies with
various combinations of attenuation correction (AC), scatter correction (SC), and system-resolution correction
(RC). This observer data was then used to evaluate a scanning channelized nonprewhitening model observer.
A standard "background-known-exactly" (BKE) task formulation overstated the prior knowledge and training
that human observers had about the hybrid images. Results from a quasi-BKE task that preserved some degree
of structural noise in the detection task demonstrated better agreement with the humans.
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H. C. Gifford, P. H. Pretorius, M. A. King, "Assessment of scanning model observers with hybrid SPECT images," Proc. SPIE 6917, Medical Imaging 2008: Image Perception, Observer Performance, and Technology Assessment, 69171C (6 March 2008); https://doi.org/10.1117/12.770994