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

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: 24 Jan 2012