Image Database for the Technical Quality Control of Mammography (2) Film digitization parameters and inconsistency of ACR-accredited phantoms.:(2) Film digitization parameters and inconsistency of ACR-accredited phantoms

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Assessment of phantom image quality is important in the quality control procedure for mammography. Digital evaluation of image quality was proposed in our previous report as a more objective method than the conventional and currently used visual scoring method. Image quality parameters, such as signal-to-noise ratio (SNR) and contrast, were studied in relation to digitization parameters. The results were as follows ; (1) for analysis of the largest three pseudo masses, 8-bit digitization gave almost the same results as 12-bit digitization, and (2) for analysis of the largest three groups of pseudo calcifications, degradation of the speck pixel value was less than 8% with 85-pm digitization compared with 50-pm digitization. Therefore, digitization of 8-bit depth and 85-pm spatial resolution can be used in phantom image analysis. On the other hand, inconsistency among ACR-accredited phantoms was found. Calcification specks showed the largest variance. In order to correct the between-phantom difference of test objects, we proposed normalization in which parameters such as SNRs are calculated as values relative to those in high-quality reference images. These normalized parameters indicate the performance level of image quality.
日本乳癌検診学会の論文