Improved image quality for dense breasts in mammography.

Within the UK breast scanning age range of 50-65 years, about 15% of breasts show a dense structure that is underexposed in conventional mammography. This gives rise to a severe reduction in contrast. Methods of improving this contrast by variation of exposure factors are explored, using a Dupont phantom that has a simulated dense breast structure. Results are assessed by considering measured contrast from a Perspex stepwedge, and by obtaining relative scores, on a scale of 1-10, from 15 radiologists involved in mammography. It is concluded from both these methods that approximately doubling the mAs at the normal kV is preferable to increasing the kV by more than a small amount. A modified mammographic technique on these lines could be valuable in selected cases where a previous conventional mammogram was available, i.e. assessment stage or repeat screening in a screening programme, or symptomatic patients. Practical problems in choosing exposure factors and the magnitude and implications of the increased dose are discussed.