Digital and film versions can be hard to reconcile, making additional tests necessary. (L-film mammogram; R-digital mammogram) Source: University of Maryland Medical Center

As digital mammography adoption increases among radiologists across the United States, the number of women who are called back for additional testing is also on the rise. According to the New York Times, during the transition period from x-ray to digital mammography, problems can arise while doctors learn to interpret digital mammograms and compare them to patients’ previous x-ray films.

Sometimes, in comparing past and present tests to look for changes, the digital and film versions can be hard to reconcile, and radiologists who are retraining their eyes and minds, may be more likely to play it safe by requesting additional x-rays — and sometimes ultrasound exams and even biopsies — in women who turn out not to have breast cancer, the NY Times reported.

Approximately 35.8 million mammograms a year are done in the United States, including those for screening and follow-ups for problems. The National Cancer Institute recommends mammograms every year or two for most women over 40, however women at high risk may be advised to start earlier. While mammography can miss tumors, even critics have said it helps to lower death rates from breast cancer, the NY Times reported.

In the United States, 32 percent of mammography clinics now have at least one digital machine, up from only 10 percent two years ago, the NY Times reported.

The rapid transition to digital is due in part because, for younger women and others with dense breast tissue, digital mammography is better than film at finding tumors and at picking up tiny calcium deposits, or calcifications, which are sometimes, but not always, a sign of cancer.

While many radiologists have said they do find themselves calling more women back, according to the NY Times, patients or their insurers are paying for the extra tests.

Fees for mammograms vary around the United States. A clinic in Manhattan recently billed an insurer $387 for a digital mammogram and then $336 for extra images of one breast — needed because of confusion between the old films and the new digital pictures — and was paid about half of those fees. Fees for film-based mammograms are usually $45 to $120 less, according to the NY Times.

Digital mammography got a boost from a large study in 2005 that showed it was better than film at finding tumors in women under 50, or women of any age who had dense breasts, meaning a lot of glandular and connective tissue in proportion to fat, the NY Times reported.