an x-ray of the breast; a method of finding breast cancer that can’t be felt using the fingers. Mammograms are done with a special type of x-ray machine used only for this purpose. A mammogram can often show a developing breast tumor before it’s big enough to be felt by a woman or even by a highly skilled health care professional. Screening mammography is used to help find breast cancer early in women who don’t have any symptoms. Diagnostic mammography helps the doctor learn more about breast masses or the cause of breast symptoms. See also screening, x-ray.