Application of parameters for evaluating different technologies for digitizing film mammograms

摘要

Taking into account requirements for processing digital mammograms, systems dealing with the optimization of images acquisition need to be adequately evaluated. The processes for generating these images are varied and they can be grouped mainly in two categories: (1) films scanned by specialized digitizers; (2) images obtained from electronic sensors associated to digital converters (CR and DR systems). The main two types of different scanners are those with white light-based detection and CCD sensors and with a scanning laser beam. Thus the current investigation aims to perform quality evaluation of film digitizers, mainly addressed to mammography. In this analysis the following parameters were studied: digitizers characteristic curves - relating the pixel value assigned to a region and the corresponding optical density of the film on the same region; noise - obtained by the Wiener spectrum; and reproducibility - evaluating whether a device used to capture a digital image can be reliable in subsequent scans. Six different digitizer equipments were investigated with purposes of determining tools to enhance the image quality based on their characteristics. The results have indicated that although the most sophisticated scanners have the best characteristics among those evaluated, knowledge about the scanner behavior can allow developing procedures to provide the adequate quality image for processing schemes.