In mammography, x-ray beams are passed through the breasts, producing images of the internal tissue on a special type of film. Periodic mammography is used as a screening tool to detect breast cancer earlier than is possible with physical examination of the breasts. It is considered to be the best, most cost-effective method of finding abnormal growths within the breast.

Purpose of the Mammography

  • To screen for tumors (benign or malignant) and cysts before they can be detected with a physical examination
  • To evaluate a woman who has symptoms of a breast disease, such as a lump, nipple discharge, or skin dimpling of the skin on the breast
  • To determine if disease is cancerous or not
  • To evaluate breast pain and breast changes
  • To evaluate any abnormalities detected in a physician or self-administered breast exam
  • To monitor women with breast cancer who have been treated with surgery and radiation

Who Performs It

A radiologist or a qualified technician performs mammograms.

Special Concerns

  • There is considerable debate regarding when women should begin to have screening mammograms. Most experts agree that periodic mammograms are beneficial in women age 50 and older; the value of regular mammography in women age 40 to 50 is more controversial.
  • Mammography is of limited usefulness in younger women, since their breasts contain more dense, glandular tissue. Since glandular tissue and tumors both appear white on x-ray film, it can be difficult to distinguish between them, increasing the possibility of a false-positive result that could lead to unnecessary biopsies. (Older women have less glandular and more fatty tissue, which appears gray on an x-ray, so potential tumors are more readily detectable.) Thus, ultrasound is preferred for examining breast tissue in younger women.
  • Pregnant women should not undergo this test because exposure to ionizing radiation may harm the fetus.

Before the Mammography

  • Your physician will explain the procedure to you. This is the time to answer any lingering questions you may have.
  • You may be asked to sign a consent form.
  • Notify your physician of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
  • You will be asked to disrobe from the waist up, remove any jewelry or metal objects, and put on an x-ray gown.
  • Do not put talcum powder, lotion, or perfume on your breasts or use deodorant on the day of the test.
  • Tell your doctor if you have breast implants or have previously undergone breast surgery. These factors may obscure the x-ray images.
  • Tell your doctor and the radiologist if you are pregnant or breastfeeding.

What You Experience

  • You will stand in front of the mammography unit.
  • A technician will position the breast being examined between two compression plates.
  • In order to obtain as clear an image as possible, the breast is compressed and flattened between the plates. This pressure will be slightly uncomfortable, but lasts only for a brief time.
  • Two x-ray photographs are taken, one from above and one from the side.
  • The same procedure is then repeated with the other breast.
  • Mammography takes only about 10 minutes to perform.

Risks and Complications

  • This procedure involves minimal exposure to radiation.
  • You may feel some discomfort as your breast is compressed. This will not harm the breast.

After the Mammography

You may be asked to wait while the films are developed to ensure they are readable. After that, you may return home and resume your usual activities.


  • A radiologist who specializes in mammography will examine the x-ray images for the presence of any unusual or suspicious shadows, masses, distortions, and differences between the two breasts. Mammography can detect lesions as small as one-quarter inch—too small to be felt during a physician breast exam.
  • If abnormalities are detected, additional tests will be required, such as another mammogram, breast ultrasound, or a breast biopsy, in order to reach a definitive diagnosis and determine the extent of the problem.
  • If the films are normal, your physician will advise you on when to return for another mammogram, usually in 1 to 2 years.


The Johns Hopkins Consumer Guide to Medical Tests

Simeon Margolis, M.D., Ph.D., Medical Editor

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 12 Jan 2012

Last Modified: 04 Nov 2014