Digital breast tomosynthesis (DBT), commonly known as a 3D mammogram, is an advanced screening tool used to detect breast cancer. This imaging technique creates a three-dimensional representation of the breast tissue, offering a clearer view than traditional methods. By capturing images from various angles, the technology reconstructs the breast into a series of thin layers, helping providers examine the tissue more thoroughly.
The Technology of Digital Breast Tomosynthesis
Digital Breast Tomosynthesis (DBT) operates using the same X-ray technology as conventional mammography. The breast is positioned and compressed between two plates, similar to a standard examination. During the imaging sequence, the X-ray tube moves in a gentle arc over the compressed breast, taking a rapid series of low-dose images from multiple angles.
This process results in approximately 11 to 25 individual projection images acquired during a single sweep. A computer uses algorithms to reconstruct this raw data into a set of fine, high-resolution slices, often as thin as one millimeter. Radiologists view these slices sequentially, moving through the breast tissue layer by layer to create the three-dimensional volume.
Comparing 3D to Standard 2D Mammography
The difference between 3D and standard 2D mammography lies in how tissue overlap is managed. In a 2D mammogram, the entire breast volume is compressed into a single, flat image. This can cause overlying normal tissue to obscure a small mass or create the appearance of an abnormality where none exists. This tissue superimposition is a limitation of conventional imaging.
DBT overcomes this by separating the tissue into thin slices, allowing the radiologist to “see around” structures that would otherwise be stacked. This slicing capability is beneficial for women with dense breast tissue. Since both glandular tissue and cancerous masses appear white on an X-ray, a tumor can be easily hidden in a 2D image.
The layered view of 3D imaging helps distinguish between overlapping dense tissue and a true abnormality. Radiologists scroll through the reconstructed volume to analyze each millimeter of the breast. This allows for a more confident assessment of a lesion’s shape, borders, and location compared to interpreting a single, compressed, two-dimensional picture.
What to Expect During the Examination
Preparation requires the patient to avoid applying deodorants, powders, or lotions to the underarm or breast area on the day of the exam, as these can create artifacts on the image. The procedure takes place with the patient standing in front of the machine while a technologist positions the breast on the imaging platform.
Compression is necessary for a 3D mammogram, as it immobilizes the breast tissue and ensures a uniform thickness for optimal imaging. The compression process is similar to a 2D exam, though some women report less discomfort with modern machines. The arm of the machine will arc over the breast during image acquisition, which is the physical difference compared to the static arm of a 2D machine.
The total time the breast is under compression is only slightly longer than the time required for a 2D view, typically lasting only a few seconds longer per view. The technologist repeats the positioning and imaging process for different views of each breast. The entire appointment usually takes around 30 minutes, and no recovery time is needed.
Clinical Impact on Screening and Diagnosis
The implementation of 3D mammography has resulted in improvements in breast cancer screening outcomes. Studies show that DBT increases the rate of cancer detection, particularly for invasive cancers, compared to screening with 2D mammography alone. Research has demonstrated an increase in cancer detection rates by 1.2 to 1.9 per 1,000 screenings.
The clearer images produced by 3D technology also reduce the number of patients recalled for follow-up testing. Because DBT better differentiates between genuine abnormalities and harmless, overlapping tissue, the false-positive recall rate is lower. This reduction in callbacks—by as much as 15% to 18.8%—decreases patient anxiety and the need for unnecessary additional imaging or biopsies. The technology is increasingly becoming the standard of care for annual screening due to these outcomes.