Increasing the utility of the mammographic phantom image.

To increase the utility of the monthly accreditation mammographic phantom image, the authors added a light sensitometric strip on the same film. The optical densities of the steps on the sensitometric strip with values nearest those of the phantom background and disk were measured, and these optical densities and the density difference were recorded and plotted on a control chart. The ability was increased to determine if changes in the contrast or optical density on an image were due to film and associated processing or to the x-ray source.