Comparing the effect of a CAD scheme applied to digitized and direct digital mammograms sets
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Recently, with the increase in the number of the FFDM, these schemes have started on being applied to images stored in the DICOM standard. Thus, this work purpose was the development of a procedure intended to detect microcalcifications and suspicious breast masses from regions of interest previously selected from digital mammograms as part of a CAD scheme. A routine designed to be applied to a mammogram in DICOM standard was developed and the stages corresponding both to microcalcifications and masses segmentation and detection were integrated to the scheme. A previous developed scheme based on the Watershed Transform to masses detection was applied to 252 ROIs from 130 digitized conventional mammograms. The results have shown 92% of true positive and 10% of false positives. For clustered microcalcifications detection, another previous developed procedure was applied to 165 ROIs from 120 mammograms, resulting in 93% of true positive and 16% of false positive. By using the same procedures to 71 digital mammograms obtained from FFDM, the rates have shown a little decrease in the scheme performance: 86% of true positive and 19% of false positive for masses detection; 90% of true positive and 29% of false positive for clusters detection. Although the tests with digital mammograms have been carried with a smaller number of images and different cases compared to the digitized ones, including several dense breasts images, the results can be considered comparable, mainly for clustered microcalcifications detection with a difference of only 3% between the sensibility rates for the both images sets. Another important feature affecting these results is the contrast difference between the two images set. This implies the need of extensive investigations not only with a larger number of cases from FFDM but also on the parameters related to its image acquisition as well as to its corresponding processing.