Mammography uses X-rays to create images of the breast. These images are called mammograms.
A radiologist trained to read mammograms studies the images for signs of breast cancer.
In the past, mammogram images were stored on film (film mammography). Now, mammogram images are usually stored directly onto a computer (digital mammography).
Digital mammography images can be lightened or darkened, and certain sections can be enlarged and looked at more closely. Because the images are stored on a computer, they can be shared easily with another radiologist for review.
Breast cancer screening tools are used to find breast cancer in a person who doesn't have any 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 they are small and 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 also be used as a follow-up test when something abnormal is found on a screening mammogram or a clinical breast exam.
When used as follow-up test (instead of screening), a mammogram may be called a “diagnostic mammogram.”
Although it’s called a “diagnostic mammogram,” it can’t diagnose breast cancer. However, it can show whether the abnormal findings look like breast cancer. If the findings look like breast cancer, you will have a biopsy to diagnose (or rule out) breast cancer.
Whether you are getting a screening mammogram or a diagnostic mammogram, the basic procedure is the same. However, you will likely have more views with a diagnostic mammogram.
If you are 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 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 and fatty breast tissue look different 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 results.
If your mammogram shows something abnormal, you will 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.
Most major health organizations conclude that mammography saves lives.
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 get a mammogram.
Learn more about the risks and benefits of mammography.
You're exposed to a small amount of radiation during a mammogram.
While the radiation exposure during mammography can increase the risk of breast cancer over time, this increase in risk is very small [2-4].
Studies show the benefits of mammography outweigh the risks from radiation exposure, especially for women ages 50 and older [2-3,5].
Special imaging machines can take multiple 2-dimensional (2D) digital images of the breast. Computer software combines the 2D X-ray images into a 3-dimensional (3D) image (called breast tomosynthesis).
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 of the images are taken.
A 3D mammogram takes a few seconds longer than a 2D mammogram because more images are taken, but you won’t likely notice a difference (if you’ve had a mammogram in the past).
Depending on the method, 3D mammography gives a slightly higher radiation dose than standard 2D mammography. This higher dose is still within FDA guidelines [6-8].
Some studies have shown 3D mammography may find a few more breast cancers than 2D mammography [6-7,9-11]. Whether 3D mammography is better than standard 2D mammography for breast cancer screening is still under study [6-7,9-11].
Currently, the American Cancer Society and the U.S. Preventive Services Task Force recommend standard 2D mammograms in their breast cancer screening guidelines [12-13].
The National Comprehensive Cancer Network breast cancer screening guidelines, however, note 3D mammography may be considered .
Some centers offer 3D mammography. Although most insurance plans cover the cost, it’s best to check with your insurance provider 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 with no out-of-pocket costs (co-payments or co-insurance) for women ages 40 and older .
If you don’t have insurance or your insurance doesn’t cover mammograms, the organizations 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).
Questions to Ask Your Doctor: Mammography
Facts for Life: Breast Calcifications
Facts for Life: Breast Density