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Is Digital Mammography Better?
| By Susan Dudley, PhD |
November 2005 |
Most Americans are familiar with the differences between new
digital cameras and their older, film-based predecessors. Similar
digital technologies are now also available for mammography. Is
this an important advance for women's healthcare? Should women
ask their doctors to give them digital mammograms instead of making
"old fashioned" film images?
To answer these questions, digital and film mammography were directly
compared in a large study recently published in the New England
Journal of Medicine. Nearly 50,000 women in the study had both
types of mammogram performed. The researchers found that for most
women, the two methods are equivalent. This means that, overall
there is no reason to be concerned about which type of machine
is being used to process your mammogram. And, since digital
mammography costs more, there is not reason to choose it.
Risks and Benefits
This study is the largest one to compare these two types of mammography.
Researchers in three earlier studies had concluded that film mammograms
are similar to or better than digital mammograms. But this new
study suggests that digital images might be better for only a
small proportion of women -
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those who are younger than 50,
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those who are pre-menopausal, and
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those who have very dense breasts.
In those groups, which overlap one another considerably,
some cancers were visible on digital images that could not be found
on film-images. We don't know yet whether finding these cancers
even earlier than film mammography could detect them will improve
the survival of cancer patients.
From a patient's perspective, the actual mammography process
and experience is about the same with either method. Nevertheless,
some advantages and disadvantages of the two have been identified,
including:
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A single exposure to radiation is sufficient to produce a
film image. With digital images, however, women with large breasts
may have to have several additional exposures to get an equivalent
image. This disadvantage would not be an issue for women with
smaller breasts.
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Digital mammography systems are not widely available at this
time, and they can cost up to four times what a conventional
film-based system does.
Because digital mammograms are stored as computer files, they may prove to be easier for medical personnel to manage. There is no need for film processing and storage, and copying and retrieval are easier.
The Bottom Line
The bottom line for women over 40 is that getting regular mammograms
is far more important than whether your screening is done on a
film or a digital machine. For most women, digital mammography
is un-necessarily expensive and may require more exposures. See
"Should
Women Over 40 Get Mammograms?" for more information on
the advantages of mammography.
Reference: Pisano, ED, Gatsonis, C, Hendrick,
E, et al. Diangostic Performance of Digital versus Film Mammography
for Breast-Cancer Screening. New England Journal of Medicine,
2005, 353 (17), pages 1773-1783.
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