A SIMPLE METHOD FOR AUTOMATICALLY LOCATING THE NIPPLE ON MAMMOGRAMS

This paper outlines a simple, fast, and accurate method for automatica lly locating the nipple on digitized mammograms that have been segment ed to reveal the skin-air interface, If the average gradient of the in tensity is computed in the direction normal to the interface and direc ted inside the breast, it is found that there is a sudden and distinct change in this parameter close to the nipple, A nipple in profile is located between two successive maxima of this parameter; otherwise, it is near the global maximum, Specifically, the nipple is located midwa y between a successive maximum and minimum of the derivative of the av erage intensity gradient; these being local turning points for a nippl e in profile and global otherwise. The method has been tested on 24 im ages, including both oblique and cranio-caudal views, from two digital mammogram databases, For 23 of the images (96%), the rms error was le ss than 1 mm at image resolutions of 400 mu m and 420 mu m per pixel, Because of its simplicity, and because it is based both on the observe d behavior of mammographic tissue intensities and on geometry, this me thod has the potential to become a generic method for locating the nip ple on mammograms.