OPTIMIZATION OF IMAGE QUALITY IN MAMMOGRAPHY

In mammography it is particularly important that the maximum amount of diagnostic information is obtained from each radiograph. One of the f actors influencing image quality is the optical density of the film. I n this work the Newcastle contrast-detail test object was used to esta blish the optimum optical density value for one film-screen combinatio n. Films taken using various mA.s values were developed in a nominally optimised film processor to mimic the real situation. The films were then viewed under optimum conditions on a variable brightness lightbox and the threshold contrast for each disc size calculated. Threshold c ontrast was plotted against optical density for each disc size and a c urve fitted through the points. The optimum optical density, taken as being the point at which the threshold contrast is a minimum varied li ttle with disc size. Averaged over all disc sizes the value of optimum density for this particular case was found to be 1.71 OD.