Digital Breast Tomosynthesis and Breast Cancer Screening
What technology is used to screen for breast cancer?
Breast cancer is the second most common cancer among women in the United States. Approximately one in eight women will develop breast cancer at some point in their lives.
The "gold standard" for diagnosing breast cancer is mammography. Several studies have shown that, in women over the age of 40, mammography greatly reduces the risk of dying from breast cancer.
Mammography is the best technology for breast cancer screening. However, mammograms are not perfect. Not all breast cancers are seen on a mammogram, especially if you have “dense” breasts.
Breasts are made up of two types of tissue: fibroglandular tissue and fatty tissue. Fibroglandular tissue is the milk glands and ducts in your breast; this tissue appears white on a mammogram. Fatty tissue appears gray on a mammogram. If the amount of fibroglandular tissue (white) is greater than the amount of fatty tissue (gray), then you have dense breasts. Almost half of all women in the United States have dense breasts.
Figure. 1. The range of breast density, from fatty breasts (far left) to extremely dense breasts (far right).
Unfortunately, many abnormalities - including cancer - also appear white on a mammogram. Since breast cancer and fibroglandular tissue are both white on a mammogram, it can be difficult to tell the difference between normal breast tissue and breast cancer. In addition, dense breasts can overlap, or “hide,” a breast cancer. When dense breasts are viewed on a mammogram, the healthcare provider may not be able to clearly see an abnormality in your breast.
What is digital breast tomosynthesis?
Digital breast tomosynthesis (DBT) is a new technology that can help improve the radiologist’s ability to diagnose your breast cancer. DBT is also known as 3D mammography because it uses a series of two-dimensional images to build a three-dimensional image of the breast. DBT was approved by the Food and Drug Administration (FDA) in 2011 and may become the new gold standard in breast imaging, especially for women with dense breasts.
What are the advantages of digital breast tomosynthesis?
DBT is especially useful in examining dense breasts and can improve the radiologist’s ability to find breast cancer. In addition, DBT offers these advantages:
- Reduces the rate of false positive readings (a reading that identifies normal tissue as an abnormality).
- Ensures that fewer women need to come back for another mammogram.
- Reduces the need for a biopsy.
- Enables the healthcare provider to more accurately locate where the abnormality is in the breast.
- May help reduce long-term anxiety while awaiting test results.
Who should have digital breast tomosynthesis?
DBT can be performed on any woman, but it is especially beneficial for women who have dense breasts.
How does digital breast tomosynthesis work?
During a mammogram, your breast is positioned on a flat support and compressed (squeezed) between two plates. The x-ray tube takes a single image.
Figure 2. The digital breast tomosynthesis system. Photo courtesy of Siemens
During a DBT exam, the breast is positioned and compressed the same way it is for a mammogram. However, during the DBT exam, the x-ray tube moves in an arc over your breast, taking pictures as it moves.
How much radiation is used in digital breast tomosynthesis?
DBT is performed at the same time as a mammogram, so the procedure takes a little longer (approximately 45 seconds). The FDA has approved DBT to be used only in combination with mammography. Therefore, the total radiation dose is just under three times that of a mammogram. The FDA considers this an acceptable and safe amount of radiation exposure.