Mammograms

Mammograms

A mammogram is an x-ray of the breast. A diagnostic mammogram is used to diagnose
breast disease in women who have breast symptoms or an abnormal result on a screening
mammogram. Screening mammograms are used to look for breast disease in women who
are asymptomatic; that is, they appear to have no breast problems. Screening
mammograms usually take 2 views (x-ray pictures taken from different angles) of each
breast, while diagnostic mammograms may take more views of the breast. For some
patients, such as women with breast implants, more pictures may be needed to include as
much breast tissue as possible. Women who are breastfeeding can still get mammograms,
but these are probably not quite as accurate because the breast tissue tends to be dense.
Breast x-rays have been done for more than 70 years, but the modern mammogram has
only existed since 1969. That was the first year x-ray units specifically for breast imaging
were available. Modern mammogram equipment designed for breast x-rays uses very low
levels of radiation, usually a dose of about 0.1 to 0.2 rads per picture (a rad is a measure
of radiation dose).
Strict guidelines ensure that mammogram equipment is safe and uses the lowest dose of
radiation possible. Many people are concerned about the exposure to x-rays, but the level
of radiation used in modern mammograms does not significantly increase the risk for
breast cancer.
To put dose into perspective, if a woman with breast cancer is treated with radiation, she
will receive around 5,000 rads. If she had yearly mammograms beginning at age 40 and
continuing until she was 90, she will have received 20 to 40 rads.
For a mammogram, the breast is pressed between 2 plates to flatten and spread the tissue.
This may be uncomfortable for a moment, but it is necessary to produce a good, readable
mammogram. The compression only lasts a few seconds. The entire procedure for a
screening mammogram takes about 20 minutes. This procedure produces a black and
white image of the breast tissue either on a large sheet of film or as a digital computer
image that is read, or interpreted, by a radiologist (a doctor trained to interpret images
from x-rays, ultrasound, MRI, and related tests).
Digital mammograms: A digital mammogram (also known as a full-field digital
mammogram, or FFDM) is like a standard mammogram in that x-rays are used to
produce an image of your breast. The differences are in the way the image is recorded,
viewed by the doctor, and stored.
Standard mammograms are recorded on large sheets of photographic film. Digital
mammograms are recorded and stored on a computer. After the exam, the doctor can look
at them on a computer screen and adjust the image size, brightness, or contrast to see
certain areas more clearly. Digital images can also be sent electronically to another site
for a remote consultation with breast specialists. Many centers do not offer the digital
option, but it is becoming more widely available.
Because digital mammograms cost more than standard mammograms, studies are now
looking at which form of mammogram will benefit more women in the long run. Some
studies have found that women who have a FFDM have to return less often for additional
imaging tests because of inconclusive areas on the original mammogram. One large study
found that a FFDM was more accurate in finding cancers in women younger than 50 and
in women with dense breast tissue, although the rates of inconclusive results were similar
between FFDM and film mammograms. It is important to remember that a standard film
mammogram also is effective for these groups of women, and that they should not miss
having a regular mammogram if a digital mammogram is not available.