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Mammography is a test that uses X-rays to create images of the breast. These images are called mammograms.
A radiologist trained to read mammograms studies the images and looks for signs of breast cancer.
In the past, mammogram images were stored on film (film mammography). Now, mammogram images are usually stored on a computer (digital mammography). This makes it easy to share digital images with another radiologist for review.
Since digital images are viewed on a computer, they can be lightened or darkened, and certain sections can be enlarged and looked at more closely.
Breast cancer screening tools are used to find breast cancer in a woman with no warning signs or symptoms.
Overall, mammography is the most effective screening tool used to find breast cancer in most women. It can find cancers at an early stage, when the chances of survival are highest.
Learn about mammography recommendations for women at average risk of breast cancer.
Learn about mammography recommendations for women at higher than average risk of breast cancer.
Mammography can be used as a follow-up test when something abnormal is found on a screening mammogram or a clinical breast exam.
A mammogram used as a follow-up test (instead of screening) is called a “diagnostic mammogram.” Although it’s called a “diagnostic mammogram,” it can’t diagnose breast cancer. It can show whether the abnormal findings look like breast cancer though.
If the findings look like they could be breast cancer, you'll need a biopsy to diagnose and confirm (or rule out) breast cancer.
Whether you're getting a screening mammogram or a diagnostic mammogram, the basic procedure is the same. However, with a diagnostic mammogram, more views will likely be taken.
If you're getting a mammogram for the first time, you may have questions about what to expect (before and after).
Learn about getting a mammogram, including information for women who have breast implants, are pregnant or breastfeeding, or who have a physical disability.
Like other X-ray images, mammograms appear in shades of black, gray and white, depending on the density of the tissue. Dense breast tissue looks different from fatty breast tissue on a mammogram.
Learn more about breast density on a mammogram.
A mammogram may show:
Learn more about findings on a mammogram and when to expect your mammography results.
If your mammogram shows something abnormal, you'll need follow-up tests to check whether or not the finding is breast cancer.
Learn about follow-up after an abnormal mammogram.
Although mammography is the most effective screening tool used today to find breast cancer in most women, it’s not perfect.
Learn about the accuracy of mammograms.
For a summary of research studies on mammography in women ages 40-49, visit the Breast Cancer Research Studies section.
For a summary of research studies on 3D mammography for breast cancer screening, visit the Breast Cancer Research Studies section.
Most major health organizations agree mammography lowers a woman's risk of dying from breast cancer [2-4].
However, there's ongoing debate about how much benefit there is from mammography (especially in younger women) and whether this benefit outweighs the risks.
There's also debate about when to begin mammography and how often to have it.
Learn more about the benefits and risks of mammography.
You're exposed to a small amount of radiation during a mammogram. While this radiation exposure might increase the risk of breast cancer over time, this increase in risk is very small [5-7].
Studies show the benefits of mammography outweigh the small risks from radiation exposure, especially for women ages 50 and older [5-6,8].
Three-dimensional (3D) mammography (called breast tomosynthesis) takes multiple 2-dimensional (2D) digital images of the breast. Computer software combines the 2D images into a 3D image.
Radiologists must have special training to read these 3D images.
Getting a 3D mammogram is similar to getting a 2D mammogram.
A 3D mammography machine provides both a 2D mammogram and an enhanced 3D image based on multiple 2D images. All the images are taken on the same machine, so you stay in one place while all the images are taken.
A 3D mammogram takes a few seconds longer than a 2D mammogram because more images are taken. If you’ve had a 2D mammogram in the past, you may not notice a difference.
3D mammography may give a slightly higher radiation dose than standard 2D mammography [3,9-10]. This higher dose is within FDA guidelines [3,9-10].
Studies show 3D mammography may find a few more breast cancers than 2D mammography [3,9-15]. Whether 3D mammography is better than standard 2D mammography for breast cancer screening is still under study [3,9-15].
The American Cancer Society and the National Comprehensive Cancer Network breast cancer screening guidelines state either 2D mammography or 3D mammography may be used for screening [3-4].
Many centers offer 3D mammography. Although most insurance plans cover the cost, it’s best to check with your insurance company and the imaging center before getting a 3D mammogram.
Learn more about screening recommendations for women at average risk.
Medicare, Medicaid and most insurance companies cover the cost of mammograms.
Since September 2010, the Affordable Care Act has required all new health insurance plans to cover screening mammograms every 1-2 years for women ages 40 and older, with no out-of-pocket costs (co-payments or co-insurance) .
If you don’t have insurance or your insurance doesn’t cover mammograms, the resources below may help you find a low-cost or free mammogram (or help with the cost).
Each October, during Breast Cancer Awareness Month, many imaging centers offer mammograms at reduced rates. To find a certified mammography center in your area, visit the FDA website (www.fda.gov).
Facts for Life: Mammography
Questions to Ask Your Doctor: Screening Mammograms
Facts for Life: Breast Calcifications
Facts for Life: Breast Density