A mammogram is an x-ray picture of the breasts. It is used to find tumors and to help tell the difference between noncancerous (benign) and cancerous (malignant) disease. One breast at a time is rested on a flat surface that contains the x-ray plate. A device called a compressor is pressed firmly against the breast to help flatten out the breast tissue. Each breast is compressed horizontally, then obliquely and an x-ray is taken of each position.
Reviewed By: Debra G. Wechter, MD, FACS, general surgery practice specializing in breast cancer, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.