Digital Mammography Available
By William Carroll, MD, PhD
In September 2005, the New England Journal of Medicine posted
the results of a large clinical trial comparing digital and film mammography.
The National Cancer Institute (NCI), which is part of the National Institutes
of Health, sponsored the trial. Researchers conducted the study under the
leadership of the American College of Radiology Imaging Network.
At the time the study results were
published, approximately 8 percent of hospitals and imaging centers were
offering digital mammography. In 2007, digital mammography became available at
Cayuga Medical Center’s Convenient Care Center at Cortland, Commons Imaging,
and at the Convenient Care Center at Ithaca and in the Imaging Services Department
at Cayuga Medical Center, for a total of four new digital mammography units.
Who participated in the NCI study?
The study included approximately
50,000 women from 33 different locations across the country. The study
participants were women with no history or current symptoms of breast cancer.
What did the study find in
comparing digital to film mammography?
The results found that the image
quality of digital mammography was superior when compared to film mammography
for three groups. These groups are: women who are younger than 50 years of age;
women who have not yet gone through menopause and women in peri-menopause,
which means that their last menstrual period was within 12 months of the time
of the study’s mammograms; and women of any age with dense breast tissue. These
three groups make up 60-65 percent of women. For women not in these three
specific categories, the study found no discernable difference between digital
and film mammography.
Over three hundred women in the
study were diagnosed with breast cancer. Of the breast cancers missed by film
mammography and detected by digital mammography, many turned out to be invasive
cancers and medium- to high-grade tumors that had not yet spread to the lymph
nodes. Detecting and diagnosing tumors before they spread is very important for
successful breast cancer treatment, which makes the study findings significant.
And because digital mammography increases the detection rate among younger
women, we are able to pick up on cancers earlier, which is important because
breast cancer in younger women is often more aggressive.
Are there other advantages to
Yes, there are a number of other
advantages to digital mammography. The files are electronic, not captured on
film, which makes storage, retrieval, and transfer of the images easier and
faster. Because digital images are viewed on a special computer monitor instead
of a light box, radiologists can manipulate the digital images using computer
enhancement to make them bigger and to increase or decrease contrast. Digital
mammography is also well suited to computer-aided detection systems. The
radiologists at Cayuga Medical Center and the Convenient Care Centers use
computer-aided detection systems now for mammograms at all three sites, as a
“second look” after we have read the mammogram. Standard mammograms typically
require a very low dose of radiation; however, digital mammograms use
approximately 25 percent less radiation than mammograms produced on film.
Is there any difference in the way
digital and film mammograms are taken?
No, the process for capturing the
images is the same. Digital mammograms require the same positioning and
compression of the breast. As with film mammograms, the technologist typically
takes two views of each breast for a digital screening mammogram.
Cayuga Medical Center radiologists
on site at each location read mammograms as they are completed so patients can
learn the results of the exam before they leave their appointments. For most
women, a baseline mammogram is recommended at age 35, with mammograms taken
annually beginning at age 40. Women with a family history of breast cancer
should talk to their primary care doctor about special guidelines for breast
Carroll is board certified in radiology and serves on the medical staff at
Cayuga Medical Center, where he is Director of Mammography.