For many years, mammograms were done by recording images of the breasts on large sheets of black and white film. As technology advanced, mammograms went digital. In digital mammograms, the images are recorded into a computer. Digital mammograms are thought to offer advantages over film mammograms, including:
- less radiation exposure per breast image
- a better breast image, especially in younger women with dense breasts (breasts that have a lower-than-average amount of fat tissue)
Mammograms are the best way for doctors to find cancer early, when it’s most treatable. Still, mammograms aren’t perfect. Normal breast tissue can hide a breast cancer so that it doesn't show up on the mammogram. This is called a false negative. And mammography can identify an abnormality that looks like a cancer, but turns out to be normal. This "false alarm" is called a false positive. Besides worrying about being diagnosed with breast cancer, a false positive means more tests and follow-up visits, which can be stressful.
So researchers are always looking for ways to make mammograms better. A German study suggests that an experimental type of digital mammogram, called digital mammography with photon-counting technique, is slightly more accurate and exposes the breasts to less radiation than traditional digital mammograms.
The research was published online on February 4, 2014 in Radiology. Read the abstract of “Digital Mammography Screening with Photon-counting Technique: Can a High Diagnostic Performance Be Realized at Low Mean Glandular Dose?
Digital mammography with photon-counting technique uses a special scanning design and special equipment that reduces what’s called scatter radiation (radiation that scatters to other areas outside the area being scanned) and noise (electron motion that can make areas of a mammogram less clear).
In the study, researchers looked at results from mammograms done from 2009 to 2010 in a screening program in North Rhine-Westphalia, the German state with the most people:
- 13,312 women got digital mammography with photon-counting technique
- 993,822 women got traditional digital mammograms
For first screenings, both types of mammogram found about the same number of cancers. For later screenings, photon-counting mammography found slightly more cancers than traditional digital mammograms. The photon-counting mammograms also found about twice the number of DCIS cases than traditional digital mammography.
The photon-counting mammogram also used less radiation: 0.64 milliGray compared to 1.79 milliGray for traditional digital mammograms. A Gray is the measurement of radiation.
Still, photon-counting mammography had a higher recall rate -- about 10% -- compared to a 7.6% recall rate for traditional digital mammograms. This means that more women were called back for more testing because of a false positive result.
Because digital mammography with photon-counting technique is so new (it received clearance from the U.S. Food and Drug Administration in February 2013), it isn’t widely available in the United States. The technology is used more in Europe, but even there it isn’t common.
Still, this study suggests the technology has promise. More research is needed to understand why the recall rates are higher and which women would most benefit from photon-counting mammograms.
Stay tuned to Breastcancer.org Research News for the latest news on advances in ways to detect and treat breast cancer.