SUBJECTIVE EVALUATION OF IMAGE QUALITY BASED ON IMAGES OBTAINED WITH A BREAST-TISSUE PHANTOM - COMPARISON WITH A CONVENTIONAL IMAGE QUALITYPHANTOM

A breast tissue phantom was used for assessment of mammographic image quality. Three images, exposed to give a reference area film density o f 1.25 +/- 0.03, were obtained for each of five different film/kV comb inations. Each of three radiologists carried out a series of three bli nd readings, in which the 15 films were ranked according to sharpness and contrast. In a similar experiment with a conventional image qualit y phantom, scores for the visualization of simulated calcifications an d contrast-detail performance, and measures for resolution and contras t were obtained. In both experiments, the judgements of the readers we re highly consistent, and both the intraobserver and interobserver var iabilities were non-significant. No significant differences between th e film/kV combinations were found with respect to high-contrast resolu tion and visualization of the simulated calcifications. The contrast m easures obtained with the conventional phantom correlated well with th e contrast scores obtained with the breast tissue phantom. The contras t-detail scores obtained with the conventional phantom showed no corre lation with the scores obtained with the breast tissue phantom, nor wi th the contrast measures obtained with the conventional phantom.