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Proceedings Paper

Size Discrimination Of Features On CT Images
Author(s): Philip F. Judy; Richard G. Swensson
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Paper Abstract

Observers rated the likelihood that two circular features on a CT image differed in size, or the likelihood that a ring was present on a CT image. The ring features were produced by subtracting the image profiles of the two disks that had to be distinguished. Since a physical cross-correlator used the same formal calculations on the image pixel values in both tasks, the signal-to-noise ratio (SNR) for the size discrimination task could be predicted from the values of SNR in the ring discrimination task. The 15 sets of images in both tasks studied three levels of feature contrast for discrimination with the relative difference in the disks' diameters adjusted to vary observers' performance over a measureable range. Indices of performance accuracy, as estimated from observers' ROC curves, were well predicted by assuming that they were proportional to the calculated values of Task SNR. The fitted constants of proportionality were similiar in both the size-discrimination (0.470) and ring-detection (0.556) tasks. Thus the human. observer's processing of image information in both the size-discrimination and ring-detection tasks was similar to, but less efficient than, that of the physical cross-correlator.

Paper Details

Date Published: 12 June 1986
PDF: 6 pages
Proc. SPIE 0626, Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems, (12 June 1986); doi: 10.1117/12.975397
Show Author Affiliations
Philip F. Judy, Harvard Medical School and Brigham and-Womens's Hospital (United States)
Richard G. Swensson, Harvard Medical School and Brigham and-Womens's Hospital (United States)


Published in SPIE Proceedings Vol. 0626:
Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems
Samuel J. Dwyer; Roger H. Schneider, Editor(s)

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