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8 March 2007Mass detection on real and synthetic mammograms: human observer templates and local statistics
In this study we estimated human observer templates associated with the detection of a realistic mass signal
superimposed on real and simulated but realistic synthetic mammographic backgrounds. Five trained naïve observers
participated in two-alternative forced-choice (2-AFC) experiments in which they were asked to detect a spherical mass
signal extracted from a mammographic phantom. This signal was superimposed on statistically stationary clustered
lumpy backgrounds (CLB) in one instance, and on nonstationary real mammographic backgrounds in another. Human
observer linear templates were estimated using a genetic algorithm. An additional 2-AFC experiment was conducted
with twin noise in order to determine which local statistical properties of the real backgrounds influenced the ability of
the human observers to detect the signal.
Results show that the estimated linear templates are not significantly different for stationary and nonstationary
backgrounds. The estimated performance of the linear template compared with the human observer is within 5% in
terms of percent correct (Pc) for the 2-AFC task. Detection efficiency is significantly higher on nonstationary real
backgrounds than on globally stationary synthetic CLB.
Using the twin-noise experiment and a new method to relate image features to observers trial to trial decisions, we found
that the local statistical properties preventing or making the detection task easier were the standard deviation and three
features derived from the neighborhood gray-tone difference matrix: coarseness, contrast and strength. These statistical
features showed a dependency with the human performance only when they are estimated within an area sufficiently
small around the searched location. These findings emphasize that nonstationary backgrounds need to be described by
their local statistics and not by global ones like the noise Wiener spectrum.
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Cyril Castella, Karen Kinkel, Francis R. Verdun, Miguel P. Eckstein, Craig K. Abbey, François O. Bochud, "Mass detection on real and synthetic mammograms: human observer templates and local statistics," Proc. SPIE 6515, Medical Imaging 2007: Image Perception, Observer Performance, and Technology Assessment, 65150U (8 March 2007); https://doi.org/10.1117/12.708492