Reported by Michael Miller
September 4, 2001
On September 4, 2001, the National Cancer Institute (NCI) and the American College of Radiology Imaging Network (ACRIN) launched a multicenter study to determine if digital mammography meets or exceeds capabilities, costs, benefits, and other factors, when compared to standard film mammography for the detection of breast cancer. Digital mammography is a technique for recording x-ray images in computer code instead of on x-ray film, as with conventional mammography. The images are displayed on a computer monitor (sometimes referred to as a workstation or viewbox) and can be enhanced before they are printed on film.
Etta Pisano, M.D., is the principal investigator for the study and Professor of Radiology in the Breast Cancer Program, Radiobiology & Imaging Program, at the University of North Carolina (UNC), Chapel Hill. Behind the News talked with Dr. Pisano about various aspects of the new study and other issues related to digital mammography.
Q: DIGITAL MAMMOGRAPHY PROMISES A LOWER RADIATION DOSE DUE TO IMPROVED X-RAY ABSORPTION. WHAT WOULD THIS MEAN FOR A 40 YEAR OLD WOMAN OVER THE COURSE OF HER LIFE WHEN COMPARING THE AMOUNT OF RADIATION FROM FILM VERSUS DIGITAL MAMMOGRAPHY?
A: We don’t have very much information on that yet. We think it’s going to reduce the dose, but we don’t know that for sure. In the ACRIN trial, we are planning to match the dose — not let the digital dose be any higher than the film dose. We can certainly get the same info out of a digital mammogram at a lower dose than film but we might be able to get more information at a higher dose. One of the limiting factors with film is that the higher the dose you apply, the worse the image gets – there’s a natural limitation. With digital, you can increase and increase the dose and you might get more information. There’s not that same limiting factor that film has. Dose (for film) was set arbitrarily many years ago and there’s no magic perfect dose. The key thing is to find the cancer, so my feeling is that if we can find cancer at a slightly higher dose within a range that’s acceptable, we might end up doing digital mammography at a higher dose (than film), not at a lower dose. More on this story..
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