A major difficulty in the interpretation of mammographic images is the low contrast and, in the case of early detection of breast cancer, the reduced size of the features of malignancy on findings such as microcalcifications. Furthermore, image assessment is subject to significant reliance of the capacity of observation of the expert that will perform it, compromising the final diagnosis accuracy. Thinking about this aspect, this study evaluated the subjectivity of visual inspection to assess the contrast-detail in mammographic images. For this, we compared the human readings of images generated with the CDMAM phantom performed by four observers, enabling to determining a threshold of contrast visibility in each diameter disks present in the phantom. These thresholds were compared graphically and by statistical measures allowing us to build a strategy for use of contrast and detail (dimensions) as parameters of quality in mammography.
The objective of this study was to compare the detection of microcalcifications and fibers on phantom images based on
monitor readings versus analog image readings. 180 films were obtained with 3 different mammographic equipment
under different exposure conditions and digitized using the Lumiscan75 scanner. It was used the ALVIM statistical
phantom (4,5cm) and 2 acrylic plates of 1cm (6,5cm) over it. The software named QualIM was developed to manager the
images and the database which storages the specialist's readings allowing them digital tools manipulation. The images
were displayed on 4 monitors: CRT Philips 19" (2,9Mpixels/8bits), CRT Philips 22" (3,0Mpixels/8bits), LCD Clinton
(3,0Mpixels/10bits) and LCD Barco (5,0Mpixels/14bits). The same images group was also displayed on the appropriated
view box to mammograms (3200cd/m<sup>2</sup>) and the readings performance was taken as reference parameter. The software
generates on real time Kappa values to microcalcifications and fibers detection, histogram, ROC curve and true/false
positive parameters. Barco monitor readings produced superior results when compared with all the others suggesting that
there weren't losses in the digitalizing process. Clinton monitor readings were similar the view box results and superior
on both Philips monitors when compared the detection of objects on phantom images (6,5cm). The specialist
performance results using Philips 22" were only comparable to view box and Clinton for images of 4,5cm. It was
possible to verify that the monitors' spatial and contrast resolutions have influenced on the readings performance of
specialists, suggesting these characteristics are relevant at lesions detection performance in mammographic exams.