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Implications of unchanged detection criteria with CAD as second reader of mammograms
KTH, School of Engineering Sciences (SCI), Physics.
2006 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 33, no 4, 922-929 p.Article in journal (Refereed) Published
Abstract [en]

In this paper we address the use of computer-aided detection (CAD) systems as second readers in mammography. The approach is based on Bayesian decision theory and its implication for the choice of optimal operating points. The choice of a certain operating point along an ROC curve corresponds to a particular tradeoff between false positives and missed cancers. By minimizing a total risk function given this tradeoff, we determine optimal decision thresholds for the radiologist and CAD system when CAD is used as a second reader. We show that under very general circumstances, the performance of the sequential system is improved if the decision threshold of the latent human decision variable is increased compared to what it would have been in the absence of the CAD system. This means that an initial stricter decision criterion should be applied by the radiologist when CAD is used as a second reader than otherwise. First and foremost, the results in this paper should be interpreted qualitatively, but an attempt is made at quantifying the effect by tuning the model to a prospective study evaluating the use of CAD as a second reader. By making some necessary and plausible assumptions, we are able to estimate the effect of the resulting suboptimal operating point. In this study of 12 860 women, we estimate that a 15% reduction in callbacks for masses could have been achieved with only about a 1.5% relative decrease in sensitivity compared to that without using a stricter initial criterion by the radiologist. For microcalcifications the corresponding values are 7% and 0.2%. (c) 2006 American Association of Physicists in Medicine.

Place, publisher, year, edition, pages
2006. Vol. 33, no 4, 922-929 p.
Keyword [en]
CAD; mammography; second reader; decision theory; optimal operating points
National Category
Natural Sciences
URN: urn:nbn:se:kth:diva-5395DOI: 10.1118/1.2179148ISI: 000237038300013ScopusID: 2-s2.0-33645510446OAI: diva2:9751
QC 20100819Available from: 2006-03-03 Created: 2006-03-03 Last updated: 2012-02-14Bibliographically approved
In thesis
1. Computer-aided detection and novel mammography imaging techniques
Open this publication in new window or tab >>Computer-aided detection and novel mammography imaging techniques
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis presents techniques constructed to aid the radiologists in detecting breast cancer, the second largest cause of cancer deaths for western women. In the first part of the thesis, a computer-aided detection (CAD) system constructed for the detection of stellate lesions is presented. Different segmentation methods and an attempt to incorporate contra-lateral information are evaluated.

In the second part, a new method for evaluating such CAD systems is presented based on constructing credible regions for the number of false positive marks per image at a certain desired target sensitivity. This method shows that the resulting regions are rather wide and this explains some of the difficulties encountered by other researchers when trying to compare CAD algorithms on different data sets. In this part an attempt to model the clinical use of CAD as a second look is also made and it shows that applying CAD in sequence to the radiologist in a routine manner, without duly altering the decision criterion of the radiologist, might very well result in suboptimal operating points.

Finally, in the third part two dual-energy imaging methods optimized for contrast-enhanced imaging of breast tumors are presented. The first is based on applying an electronic threshold to a photon-counting digital detector to discriminate between high- and low-energy photons. This allows simultaneous acquisition of the high- and low-energy images. The second method is based on the geometry of a scanned multi-slit system and also allows single-shot contrast-enhanced dual-energy mammography by filtering the x-ray beam that reaches different detector lines differently.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006
Trita-FYS, ISSN 0280-316X ; 2006:06
computer-aided detection, FROC, mammography, optimal operating points, single-shot dual-energy imaging
National Category
Radiology, Nuclear Medicine and Medical Imaging
urn:nbn:se:kth:diva-3861 (URN)91-7178-274-5 (ISBN)
Public defence
2006-03-10, Sal F3, Lindstedtsvägen 26, Stockholm, 10:00
QC 20100819Available from: 2006-03-03 Created: 2006-03-03 Last updated: 2010-08-19Bibliographically approved

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