[Use of the ROC method in problems of image quality and quality control in mammography]

The ROC method is being used increasingly in radiology for the purpose of checking image quality. A phantom has been developed for use in mammography, which takes account of the tissues of the breast and of abnormal changes. In order to compare image quality, various films and film-screen systems were employed. The effect of slice-thickness, focal spot size and radiation scatter on image quality has been examined. The suitability of the method for quality control has been tested on a small sample. In addition, certain important parameters of the radiographic technique have been determined by physical measurements. Certain methodological difficulties must be considered, eg. the problem of statistical significance. It has been shown, however, that film-screen systems can approach the image quality of screenless films and require a lower dose of x-rays. For larger slice thickness, the use of a grid produces significantly better results than film without screens alone. The findings of the quality control show that it is important to check image quality by means of physical measurements. The ROC method has proved less valuable in this respect.