Digital Breast Tomosynthesis (DBT), or 3D mammography, is an advanced form of X-ray imaging used for breast cancer screening. This technology provides a significant improvement over traditional two-dimensional (2D) mammography. DBT creates a clearer picture of the breast tissue, aiding in the early detection of abnormalities, and is becoming the preferred method for many healthcare providers.
The Technology Behind Tomosynthesis
Digital Breast Tomosynthesis involves the X-ray tube moving in a controlled arc over the compressed breast tissue. During this movement, the machine captures multiple, low-dose X-ray exposures from various angles. This collection of projection images is then sent to a computer for processing and reconstruction.
The computer algorithm uses the angular data to synthesize a three-dimensional volume of the breast tissue. This volume is presented to the radiologist as a series of thin, distinct “slices,” often measuring about one millimeter in thickness. Unlike traditional 2D mammography, which captures all tissue in a single, flat image, DBT separates overlapping structures. This layered approach overcomes the limitation of tissue superimposition.
What to Expect During the Procedure
The patient experience during a 3D mammogram is very similar to a conventional 2D exam, requiring minimal additional preparation. Patients are asked to undress from the waist up and are positioned in front of the machine, where the breast is placed on a support plate. Compression is necessary, as it immobilizes the breast and spreads the tissue to allow for a clearer image with a lower radiation dose.
While the breast is compressed, the X-ray tube head sweeps across the breast in a gentle arc, a movement the patient will notice. The acquisition of multiple images takes only a few seconds per view. The entire appointment, including positioning for both breasts, typically takes 20 to 30 minutes.
Key Advantages Over Traditional Screening
The ability of DBT to render breast tissue in thin layers offers substantial clinical benefits compared to 2D mammography. The primary advantage is superior cancer detection, particularly for women with dense breast tissue. In dense breasts, glandular and fibrous tissue can obscure a tumor on a 2D image. The layered view allows the radiologist to look past normal, overlapping structures to identify subtle abnormalities.
Another element is a marked reduction in the rate of false positives, which are abnormal findings that turn out not to be cancer. Traditional 2D screening often requires a patient callback for additional imaging when tissue overlap creates a suspicious shadow. By separating these shadows into distinct slices, the 3D method helps the radiologist determine that the finding was merely superimposed normal tissue. This reduces patient anxiety and the need for unnecessary follow-up procedures.
Addressing Common Patient Questions
A frequent question concerns the amount of radiation exposure during a 3D mammogram, given that multiple images are captured. While DBT may involve a slightly higher dose than a standard 2D view, the total radiation exposure remains within the safety limits established by regulatory bodies like the U.S. Food and Drug Administration (FDA). Modern DBT systems often achieve doses comparable to, or even less than, some older 2D machines.
Another element is the coverage and cost of the newer technology. Insurance coverage for 3D mammograms is increasingly widespread, with many major providers, including Medicare, offering coverage. Coverage can vary depending on the specific insurance plan and state mandates. Patients should verify their policy details and inquire about any potential out-of-pocket costs before their appointment.
While DBT is suitable for all women undergoing routine screening, it is particularly helpful for those with dense breast tissue or elevated risk factors for breast cancer. The enhanced detail makes it a strong option for women who have historically received unclear results from 2D screenings.