Skin edge perception in mammograms: a comparison of two film-screen combinations

The entire skin edge is not always seen on mammograms. The importance of de monstrating the full extent of the breast on a mammogram is uncertain, but there are implications for optimizing film design and use. The new Agfa HDR film has been designed to improve visualization of the skin edge without c ompromising overall contrast. A quantitative and qualitative comparison bet ween Agfa HDR and the Fuji UMMA film has been performed. A total of 216 mam mograms from 54 symptomatic women were analysed. For each view on each woma n, one breast was imaged using Fuji UMMA film and the other using Agfa HDR film. The target density achieved on quality control films of PMMA blocks w as 1.70+/-0.10 for both film types. A radiologist graded the skin edges of all the films as visible, just visible or dark. Measurements were made of t he optical densities in the skin edge region and on the fully exposed black part of the film, adjacent to the skin line. 70% of the HDR films had visi ble skin edges compared with 43% of the UMMA films. 2% of the HDR films had dark skin edges compared with 26% of the UMMA films. Optical densities at the skin edge were broadly similar for the two films and in the range 3.6+/ -0.3. However, the density of the black part of the Agfa film was about 0.5 higher than with the Fuji film and it appears that this was the main reaso n the skin edge region was better visualized with the Agfa film.