Mammography is the process of using low-dose x-rays to create detailed images of the breast.  It can show changes in a women's breast up to 2 years before the woman or her physician can feel them, making it possible to detect tumors. At this time, mammography along with physical breast examination is still the modality of choice for screening for early breast cancer.

There are two types of mammography: "Screening" and "Diagnostic". A screening mammogram is an x-ray of the breast used to screen for changes in women who have had no prior abnormalities. Mammograms can also find microcalcifications (tiny deposits  of calcium in the breast) that sometimes indicate the presence of breast cancer.

A diagnostic mammogram is an x-ray of the breast that is used to check for breast cancer after a lump or other sign or symptom of breast cancer has been found. Signs of breast cancer may include pain, skin thickening, nipple discharge or a change in breast size or shape. A diagnostic mammogram may be used to evaluate changes found during a screening mammogram, or to view breast tissue when it is difficult to obtain a screening mammogram because of special circumstances, such as the presence of breast implants.

A diagnostic mammogram takes longer than a screening mammogram because it involves more x-rays in order to obtain views of the breast from several angles. The technician may magnify a suspicious area to produce a detailed picture that can help the doctor make an accurate diagnosis.