This page was reviewed under our medical and editorial policy by

Daniel Liu, MD, Plastic and Reconstructive Surgeon

This page was reviewed on February 18, 2022.

Mammograms capture sharp, digital images of the breasts. Once the digital images are obtained and transmitted to a digital mammography workstation, radiologists analyze the images to determine the precise location and extent of the disease.

This article will cover:

What is a mammogram?

A mammogram is an X-ray exam that may also identify breast changes and locate tumors that are too small or too deep to be detected with a breast examination. For women experiencing symptoms such as a lump, pain, skin dimpling or nipple discharge, a mammogram may determine whether the side effects are a result of cancer or another condition.

Mammograms are an important tool in the early detection of breast cancers because they may show changes in the breast months or years before a patient is able to feel them. Current guidelines from the U.S. Department of Health and Human Services and the American College of Radiology recommend mammography screening every year for women, beginning at the age of 40. A mammogram may also help determine whether a woman has dense breasts, meaning their breasts have more of the type of glandular tissue that is of higher risk for developing cancer.

The mammography unit is designed to accommodate virtually any size breast, large or small. During a mammogram, the breasts are compressed, one at a time, between two firm surfaces that flatten the breast tissue for improved imaging. Some patients may experience mild discomfort depending on the sensitivity of their breasts, but the pressure lasts only a few seconds. Multiple images of the breast are taken with X-ray technology, and the images are displayed on a computer screen and examined for signs of cancer.

If an abnormality is detected, it may or may not require treatment. The care team may recommend further tests, such as an ultrasound or MRI. If the radiologist believes the abnormality needs further study, a biopsy may be performed to determine whether the mass is cancerous.

Types of mammograms

Computer-aided detection (CAD) for mammography

CAD for mammograms is used to analyze mammographic images and check for the presence of breast cancer. The CAD system analyzes digital information collected by a mammogram and then computer software searches for abnormal areas of density, mass or breast calcification. The system highlights suspicious areas, alerting doctors to the need for further analysis.

The CAD system may improve the detection of cancer in the breast by acting as a second set of eyes to find abnormal areas on a mammogram.

Digital breast tomosynthesis (3D mammogram)

Digital breast tomosynthesis creates a 3-D picture of the breast. Tomosynthesis is similar to a standard mammogram in that it uses X-ray technology and applies the same amount of pressure to the breast. But rather than providing two views—from top to bottom and side to side—the 3-D approach captures multiple views from a variety of angles in seconds.

During the procedure, an X-ray tube moves in an arc around the breast, capturing multiple images that are used to create a detailed, layer-by-layer view of the tissue. This cross-sectional perspective helps to separate overlapping tissue densities, allowing radiologists to detect cancer at an earlier stage.

Images are sent to a computer to create a clear, highly focused 3-D image. Tomosynthesis may be used along with traditional digital mammograms as part of an annual screening. The technology is approved by the U.S. Food and Drug Administration as a screening tool for breast cancer.

Full-field digital mammography

This mammography unit captures an electronic picture of the breast in digital format. Once they are transmitted to a high-tech, digital mammogram workstation, the images are used to determine the precise location and extent of the disease. Because the images appear on a computer screen, doctors can adjust the image size, brightness and contrast to see certain areas more clearly.

How to prepare for a mammogram

Before the appointment

  • Find the right facility for the patient's preferences. The care team might recommend a specific location, but it’s helpful to do independent research as well. Consider choosing a center or facility that specializes in breast imaging and mammograms.
  • Be consistent. After choosing a location that fits the patient's needs, try to visit the same location for subsequent screenings. This way, the patient's mammograms can easily be compared year over year. If the patient does go to a new facility, she should keep all of her mammogram records and related documents organized so that the new technologist can more accurately assess her medical history.
  • Schedule the mammogram for the optimal time. Avoid scheduling a mammogram during or right after menstruation, as a woman's breasts may be tender or swollen. Also, make sure to tell the mammography facility about any breast implants.
  • Avoid wearing deodorant. The U.S. Centers for Disease Control and Prevention (CDC) recommends not wearing deodorant/antiperspirant, baby powder, perfume or lotion, as some of these products contain substances that can appear as white spots on the X-ray.
  • Dress accordingly. Before the mammogram, the patient will be asked to remove her top and bra for the X-ray, so it might be more convenient to wear a loose top and pants or a skirt versus a dress, one-piece or tight clothing. The facility will provide a wrap or gown to wear.
  • Keep all medical records organized. The technologist will ask for personal and medical history, such as past surgeries, hormone use, breast cancer in the family or if the patient has had breast cancer before.

During the mammogram

  • Be prepared for the placement. Each breast will be placed between two plates that will compress or flatten the breast to spread the tissue apart. The imaging machine will then take X-ray pictures, typically from two different angles.
  • Allot enough time. The entire procedure should take about 20 minutes, with each breast compression lasting a few seconds each.
  • Don’t be afraid to speak up. It’s not uncommon to feel some pain or discomfort during a mammography, so speak up to the technologist if the pain is too much. The patient might also be a little sensitive to the coldness of the plates.
  • Lean on a loved one. If the patient has anxiety ahead of the appointment, it might help to bring someone along for support. Check with the facility beforehand to see if there are any restrictions on bringing support.

After the mammogram

  • Review test results. Following the test, a radiologist will review the mammogram and assign a BI-RADS score, which guides the care team as they determine next steps. The patient will be contacted with the results typically within 10 days, and she'll also receive a full report from the center or clinic typically within 30 days. 

Why is mammogram screening so important?

In 2024, approximately 310,720 new cases of invasive breast cancer will be diagnosed in the United States, according to the American Cancer Society (ACS). These numbers reinforce the importance of breast cancer screening, which largely includes a traditional mammogram, while some facilities also offer three-dimensional (3D) mammograms.

Mammogram screening guidelines

First and foremost, the patient should speak directly with her doctor about the benefits and risks of getting a mammogram, when to start screening and how often to get screened based on her individual medical history. The American College of Radiology (ACR) and the American College of Surgeons' National Accreditation Program for Breast Centers recommend the following screening recommendations for women with average risk:

  • Begin annual mammogram screening at age 40.
  • Women between 55 to 75 with average risk should schedule a mammogram once every one to two years.
  • Women over 75 with average risk should continue to schedule a mammogram depending on overall health, including a life expectancy of 10 years or more.

Additional screening recommendations may be suggested for women with high risk, including those who have a BRCA1 or BRCA2 mutation, who are an untested family member of someone who has BRCA1 or BRCA2 mutation, have a history of mantle or chest radiation occurring before age 30 or who have a family history of breast cancer risk of 20 percent or greater, based on their family history, according to the ACR.

Screening vs. diagnostic mammograms

Screening and diagnostic mammograms are performed using the same technology, but they have different intents:

Screening mammograms are performed to detect possible signs of breast cancer before patients experience symptoms of the disease.

Diagnostic mammograms are performed to more closely examine the breast tissue, typically following symptoms or after a screening mammogram shows suspicious results. During diagnostic mammograms, the technologist will take more images than in a screening mammogram, and in some cases, the radiologist may request additional views in real time.

Mammogram radiation risks

While patients are exposed to a small amount of radiation during the X-ray process that produces the breast imaging, the radiation doesn’t affect everyone the same. The risk is greater for women younger than 40 years old, according to the National Institutes of Health, and the X-ray technologist should always know whether the patient is or may be pregnant. According to the ACS, the benefits of mammography to detect breast cancer under age 40 greatly outweigh the risks of radiation exposure.

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Show references
  • Centers for Disease Control and Prevention (2022, September 26). What Is a Mammogram?
  • American Cancer Society (2023, January 12). Key Statistics for Breast Cancer.
  • American College of Radiology (2018, February 15). Breast Cancer Screening in Women of Higher-Than-Average Risk: Recommendations from the ACR.
  • National Institute of Biomedical Imaging and Bioengineering (2022). Mammography.
  • American Cancer Society (2022, January 14). Mammogram Basics.