Mammography

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

S Meeson1, KC Young1 and J Cooke2

1National Co-ordinating Centre for the Physics of Mammography, St. Luke's Wing, Royal Surrey County Hospital, Guildford GU2 7XX. 2Jarvis Breast Screening Centre, 60 Stoughton Road, Guildford GU1 1LJ, UK.

The entire "skin edge" cannot be seen on some mammograms. The importance of seeing the full extent of the breast on a mammogram is uncertain, but there are implications for optimising film design and use. A new film from Agfa, Agfa HDR, has been designed to improve the visualisation of the skin edge without compromising overall contrast. A quantitative and qualitative comparison between Agfa HDR and the Fuji UMMA film has been performed. A total of 216 mammograms from 54 women who had undergone symptomatic mammography were analysed. For each view on each woman one breast was imaged using the current Fuji UMMA film and the other using the new Agfa HDR film. The target density achieved on quality control films of PMMA blocks was 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 the 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 visible skin edges compared to 43 % of the UMMA films. 2 % of the HDR films had dark skin edges compared to 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 reason the skin edge region was better visualised with the Agfa film.

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Figure 1 from this paper (below) appeared on the front cover of the printed journal.

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