Composition of mammographic phantom materials.

Abstract

To determine the composition of a breast phantom that is most suitable for phototimer testing. Kilovolt peak and milliampere second values were analyzed for phototimed exposures of phantoms containing 0%, 30%, 50%, 70%, and 100% simulated glandular material at thicknesses of 2, 4, 6, and 8 cm. Data also were analyzed from 1,578 mammograms in 417 patients. The mean effective glandular content of phantoms that simulated patient breasts of varying thicknesses was determined. Examination of mammographic techniques showed that the effective glandular content that simulated the average patient breast was 34%. Effective glandular content was 16% in breasts at least 7 cm thick when compressed; 26%, more than 5 to up to 7 cm thick; 42%, more than 3 to up to 5 cm thick, and 68% in breasts at most 3 cm thick. A phantom composed of 30% glandular tissue and 70% adipose tissue allows closer simulation of the phototimer response of the mammographic x-ray unit for the average breast. The phantom currently used contains 16% more glandular tissue than the average breast.