A new phantom for mammography. A new mammography phantom from Du Pont is described. It has a wider range of types of detail than in previous phantoms, including some which closely simulate breast tissues. Experience of its use, and comparisons with an earlier ("Barts") phantom, are reported. The Du Pont phantom appears to have greater sensitivity to changes in tube kV and focal spot size, and better discrimination between different film-screen combinations and between films from different breast screening centres. 