Digital Tomosynthesis (3D Mammogram)

April 10, 2025

This page was reviewed under our medical and editorial policy by Leah Naghi, M.D., assistant clinical professor, and Susan Yost, Ph.D., staff scientist, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte

Breast tomosynthesis, also known as three-dimensional (3D) mammography, is a specialized type of mammogram that helps detect abnormal changes in the breast.

Unlike traditional two-dimensional (2D) mammograms, this advanced imaging technique takes multiple pictures of the breast from different angles, creating a detailed, layered view. This may make it easier to spot small tumors or other signs of breast cancer that might not be visible on standard mammograms.

It is an important tool for early detection, especially in women without any symptoms.

What Is Breast Tomosynthesis?

Breast tomosynthesis is a more advanced way to view the breast for any changes, such as signs of breast cancer. Like a traditional mammogram, it uses low-dose X-rays to take pictures of the breast. Breast tomosynthesis captures many images from different angles as the X-ray machine moves around the breast in a small arc.

These images are then combined by a computer to create a detailed, 3D view of the breast tissue. This allows doctors to see the tissue in thin "slices," much like flipping through the pages of a book. This technique helps radiologists, who are doctors trained to interpret screening images, to spot any abnormal areas that might be hidden on a traditional 2D mammogram.

The 3D images make it easier to detect small tumors and other changes, especially in women with dense breast tissue. While breast tomosynthesis uses a very low dose of X-rays, it is often performed alongside a standard 2D mammogram, so the overall radiation exposure is slightly higher. Despite this, the benefits of more accurate detection and fewer follow-up tests may outweigh the risks.

Breast tomosynthesis is becoming a common breast cancer screening tool, especially in areas with access to advanced medical technology.

2D Versus 3D Mammogram

A 2D mammogram takes two X-ray images of each breast: one from the top and one from the side. This type of mammogram is routinely used for screening. While it is an appropriate screening method, it may sometimes miss small abnormalities because overlapping tissue might hide them.

In contrast, a 3D mammogram captures multiple images from different angles as the machine moves around the breast. A computer then combines these images to create a detailed, 3D view. This makes it easier for doctors to detect hidden tumors, especially in dense breast tissue.

Although 3D mammograms often cost more, they may reduce the need for follow-up tests.

How Is Digital Breast Tomosynthesis Performed?

Before breast tomosynthesis imaging, patients should discuss any breast changes or concerns with their doctor.

Those who usually have tender breasts close to their menstrual period may want to avoid scheduling the exam during the week that precedes it. Patients should not wear deodorant, lotion or powder on the day of the exam, as these may interfere with the X-ray images.

During the procedure, a specially trained radiologic technologist guides the patient through the process. The patient stands in front of a mammography machine, and one breast is positioned on a special platform. A clear plastic paddle then compresses the breast. This compression is necessary to spread out the breast tissue, allowing for clearer images.

While the compression might be uncomfortable, it is necessary to obtain accurate results. If the patient experiences significant discomfort, the technologist is able to adjust the pressure. Once the breast is compressed, the X-ray machine moves in a small arc around it, capturing multiple images from different angles.

This step usually takes a few seconds. The patient is asked to remain still and may need to hold their breath briefly to avoid blurry images. The process is then repeated for the other breast.

After the images are taken, the technologist may ask the patient to wait while they check that all necessary views have been captured.

The technologist will advise the patient on when to expect the results. If the results are not received within the expected timeframe, the patient should follow up with their doctor or the imaging center.

How Long Does a 3D Mammogram Take?

The breast tomosynthesis procedure usually takes about 30 minutes from start to finish. Patients may need to add time for check-in and getting set up before the actual imaging.

Sometimes, the radiologist may ask for additional images if the first ones are not clear, which may add a few more minutes.

Overall, patients should expect the entire process to be relatively quick and straightforward.

What If Results Indicate an Abnormal 3D Mammogram?

After a 3D mammogram, a radiologist reviews the images and sends a report to the patient’s primary doctor. The doctor discusses the findings with the patient and explains what the next steps might be if there are any abnormalities. Patients often also receive a notification of the results from the mammography in their patient portal. They may see a BI-RADS category listed, which stands for Breast Imaging Reporting and Data System. This classification system helps nonradiologists better understand mammogram results.

In many cases, an abnormal result does not mean cancer but may require further testing. The doctor may recommend a follow-up exam, such as additional mammogram views or a breast ultrasound, to take a closer look at the area of concern. If the follow-up images still show something suspicious, the next step may be a breast biopsy. This is a procedure in which a small sample of tissue is taken from the breast to check for cancer cells under a microscope.

Most of the time, a biopsy identifies a benign (noncancerous) condition that may be monitored or treated. If a biopsy confirms cancer, the patient will be referred to specialists, such as a surgical oncologist. A team of doctors, including oncologists, surgeons and radiologists, may also discuss the case in order to create a personalized breast cancer treatment plan. The process from identifying a concern to getting a diagnosis usually takes a few weeks, depending on the tests needed.