A mammogram is a type of X-ray for the breasts. A screening mammogram usually involves two X-rays of each breast. A diagnostic mammogram involves more X-rays.

Who is a candidate for the test?

A screening mammogram is generally used to detect breast cancer or other changes in the breast tissue in women who do not have symptoms.

A diagnostic mammogram may be ordered when a screening mammogram shows something abnormal in the breast. It may also be ordered if the woman has symptoms, such as the following:
- a discharge from the nipple other than breast milk
- a lump or swelling in the breast or underarm area
- nipple pain
- redness or scaliness of the nipple or breast skin
- retraction, or turning inward, of the nipple
- skin irritation or dimpling

Breast cancer screening with mammograms has reduced deaths from breast cancer in women 40 to 69 years of age.

How is the test performed?
For a screening mammography, the woman undresses to the waist and puts on a gown that opens from the front. The technologist places one breast on an X-ray film cassette, which resembles a metal shelf. The woman rests her breast on the film cassette. Usually the woman stands during this procedure.

A plastic paddle briefly squeezes the breast from above to flatten it out. This allows a clearer X-ray to be taken. Two views are usually taken of each breast for a screening mammogram. A diagnostic mammogram requires more views and more detail than the screening exam. With modern mammography equipment used specifically for breast X-rays, very low levels of radiation are used.