CDMAM Analysis

Automated determination of threshold contrast

The data used in the analysis

European Guidelines provide quality control procedures and minimum standards of performance for digital mammography. The image quality standard is based on contrast-detail measurements using the CDMAM phantom (version 3.4, UMC St. Radboud, Nijmegen University, Netherlands). The minimum standards were chosen to ensure that digital systems are as good or better than current film screen systems. These standards have also been incorporated into guidance to the NHS Breast screening programme. Such contrast detail measurements rely on a large number of observer readings and suffer from significant inter-observer error, which undermines the reliability and confidence in the measurements. The use of human observers is also very time consuming. A possible solution to these problems is the use of the software which automatically reads CDMAM images.

The resulting graph of the curve fits and the contrast detail plot

The basic software tool described by Karssemeijer and Thijssen for automatically identifying discs on digital images of the CDMAM is called CDCOM and is available for download at the EUREF website. Also provided at this website is a manual explaining how to use the software. The CDCOM program attempts to correctly locate the position of the gold discs on a single DICOM image. However the program does not combine the data from more than one image or determine the threshold contrasts.