Digital Mamography

Breast cancer is the second most common cancer in women in the U.S. It is second only to skin cancer.

Fortunately, deaths caused by breast cancer have declined over the past 20 years. Many experts believe this is, in part, a result of improved screening and treatment techniques. Mammograms are the preferred diagnostic test to find breast cancer in its early stages. They do this by using X-rays to scan the breasts for cancer.

For many years, the only option was mammograms that record images of the breast on film. Now, digital mammograms are available. Digital mammograms store and analyze the information using a computer.

How do film and digital mammograms work?

All mammograms work by sending X-rays through the breast tissue to obtain images. These pictures are then analyzed for abnormalities and assessed for changes from previous tests. Whether your doctor recommends a film or digital mammogram, your testing experience will be the same.

To get the best images possible in either a film or digital mammogram, the technologist needs to flatten and compress your breasts before taking images. Your breasts will be flattened between two special plates before X-rays are used to take the image. For both types of mammograms, the entire test lasts about 20 minutes.

X-rays have been used for nearly a century to detect breast cancer. But the modern-day film mammogram was invented in 1969. In this procedure, images are recorded on film much in the way a traditional film camera takes pictures.

In a digital mammogram, X-rays are still used. But they are turned into electric signals that can then be stored in a computer. This is similar to the way digital cameras take and store pictures.

How do rates of detecting breast cancer compare for film and digital mammograms?

Although film mammograms are very effective, some research suggests that they may miss between 10% and 20% percent of breast cancers.

A study published in September 2005 in the New England Journal of Medicine compared digital mammograms to film mammograms. The study involved 49,000 women in North America with no known signs of breast cancer. The women were screened using both digital and film mammograms at the beginning of the study and again one year later. Breast cancer was found in 335 of the women. The researchers determined that digital mammograms were superior to film mammograms for three groups:

• women under 50 years of age
• women with dense breasts
• women who have not yet gone through menopause, or who have been in menopause less than one year.

Digital mammograms did not prove to be more beneficial for post-menopausal women over age 50 that do not have dense breasts. Additionally, both forms of mammogram had the same rate of false positives.

It cannot be told from the study whether the increased use of digital mammography over film mammography would result in fewer deaths. However, the researchers did note that the types of cancer caught by digital mammograms after being missed on film are the forms of the disease that can be fatal.

What are the potential benefits of digital mammograms?

• Enhanced interpretation. Mammograms can be extremely difficult for radiologists to interpret. Digital mammograms, though, are stored electronically. That means they can be analyzed by computers as well as by radiologists.
• Image manipulation capabilities. Film mammogram images cannot be changed. Digital mammogram images can be manipulated digitally for better clarity and visibility. For instance, the contrast of the images can be changed where necessary to provide a clearer picture.
• Lower average radiation dosage. Digital mammograms may take more views of each breast than film mammograms. But they use approximately 25% less radiation than film mammograms. That’s because smaller areas of the breast are imaged in each view.
• Easier second opinions. Since digital mammograms are stored in computers, they can easily be sent electronically to other health care professionals for analysis.
• Easier to store. Film mammograms produce bulky sets of films that must be stored and revisited for comparison in future tests. Digital mammogram results are stored on computers for ease of access and retrieval.

Who should get a digital mammogram?

Women younger than 50, premenopausal or perimenopausal (those with a menopause duration of less than 1 year) women, and women with dense breasts might benefit from digital mammogram screenings. For other groups of women, research indicates that film and digital mammograms have similar detection results.

Digital mammograms cost much more than film mammograms. And the vast majority of mammogram facilities in the U.S. do not have digital capabilities. However, even if you are a woman that might benefit from digital mammograms, not having access to digital mammogram technology does not mean you should forego a regular film mammogram.

The American Cancer Society recommends that all women age 40 and above have an annual mammogram to screen for breast cancer. The U.S. Preventive Services Task Force (USPSTF) does not recommend screening for women in their 40s. For women between the ages of 50 and 74, USPSTF experts say women should have mammograms every two years.

If you are at high risk for developing breast cancer, you might also benefit from an annual MRI in addition to a yearly mammogram.