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

A breast tissue phantom was used for assessment of mammographic image quality. Three images, exposed to give a reference area film density of 1.25 +/- 0.03, were obtained for each of five different film/kV combinations. Each of three radiologists carried out a series of three blind readings, in which the 15 films were ranked according to sharpness and contrast. In a similar experiment with a conventional image quality phantom, scores for the visualization of simulated calcifications and contrast-detail performance, and measures for resolution and contrast were obtained. In both experiments, the judgements of the readers were highly consistent, and both the intraobserver and interobserver variabilities were non-significant. No significant differences between the film/kV combinations were found with respect to high-contrast resolution and visualization of the simulated calcifications. The contrast measures obtained with the conventional phantom correlated well with the contrast scores obtained with the breast tissue phantom. The contrast-detail scores obtained with the conventional phantom showed no correlation with the scores obtained with the breast tissue phantom, nor with the contrast measures obtained with the conventional phantom.