Digital mammography uses low-dose X-rays to create detailed images of breast tissue, utilizing a computer system instead of traditional film. This modern technique aids in the early detection and diagnosis of breast cancer. It provides a platform for both routine screening and more focused diagnostic evaluations.
The Technology: How Digital Imaging is Captured
The core mechanism of digital mammography replaces the traditional film cassette with an electronic detector plate, often called a flat-panel detector. This solid-state detector is similar to technology found in high-resolution digital cameras. When the X-ray beam passes through the compressed breast tissue, the detector captures the energy.
The captured X-ray energy is instantly converted into electrical signals, which are then digitized and processed into a high-resolution image composed of millions of pixels. This immediate digital conversion allows the image data to be transferred directly to a computer monitor for viewing and analysis within seconds. This rapid process eliminates the time-consuming chemical development required by older film systems.
Key Differences from Traditional Film Screening
A major advantage of digital technology is the ability to manipulate the image data after acquisition. Radiologists can adjust the brightness, modify the contrast, and zoom in on specific areas of concern without needing a new X-ray. This post-acquisition processing allows for a more detailed examination, helping to distinguish subtle tissue changes.
Digital systems require a lower radiation dose than film systems because the electronic detectors are more sensitive to X-ray energy. The electronic nature of the images simplifies record-keeping and sharing, as images can be stored on Picture Archiving and Communication Systems (PACS) and transmitted securely between medical facilities. Digital storage also reduces the rate of repeat X-rays.
Digital Breast Tomosynthesis (3D Mammography) Explained
Digital Breast Tomosynthesis (DBT), commonly known as 3D mammography, is an advanced form of digital imaging. Unlike standard digital mammography, which captures a single 2D view, DBT captures a series of low-dose images from multiple angles. During the exam, the X-ray tube moves in an arc over the compressed breast.
A sophisticated computer algorithm uses these projection images to reconstruct a three-dimensional volume of the breast tissue. This reconstruction creates thin, 1-millimeter “slices” of the breast, similar to a Computed Tomography (CT) scan. Viewing the tissue in thin layers addresses the problem of tissue overlap, which can hide small cancers or create false alarms in 2D images.
DBT is particularly beneficial for women with dense breast tissue, where overlapping normal tissue can obscure a tumor. By separating the tissue layers, the 3D view allows radiologists to see through the density, leading to better cancer detection rates and reducing patient recalls for additional imaging. Many modern DBT systems generate a “synthetic” 2D image from the 3D data, keeping the overall radiation exposure comparable to a standard 2D digital mammogram.
Preparing for and Undergoing the Procedure
Patients should avoid applying deodorant, antiperspirants, powders, lotions, or creams to the chest area or under the arms on the day of the exam. These products often contain metallic particles that can appear on the X-ray as white spots, potentially interfering with image interpretation. It is helpful to wear a two-piece outfit, as only clothing above the waist needs to be removed.
The technologist positions the breast on the machine’s platform, and a clear plastic paddle gently and firmly compresses the tissue. Compression is necessary because it evens out breast thickness, reduces motion blur, and minimizes the required radiation dose. Although compression can cause temporary discomfort, it lasts only for the few seconds required to capture the images.
The entire procedure involves taking two views of each breast (top-to-bottom and side-to-side) and typically takes between 15 and 30 minutes. Once the images are acquired, the patient is free to leave, and the final report is usually sent to the referring healthcare provider within a few days.