Breast Cancer Mammogram
A mammogram is typically an x-ray of the breast. A diagnostic
mammogram is employed to diagnose breast disease in women who have
breast symptoms. Screening mammograms are commonly used to look for
breast disease in women who are asymptomatic; that is, those who appear
to have no breast problems. Screening mammograms typically involve 2
views (x-ray pictures taken from different angles) of each breast. Women
who are into breast-feeding can still get mammograms, although these are
probably not quite as accurate.
Even though breast x-rays have been performed for more than 70 years,
modern mammography has only existed since 1969. That was the year x-ray
units dedicated to breast imaging were available. The modern mammogram
equipment designed for breast x-rays uses very low levels of radiation,
usually about a 0.1 to 0.2 rad dose per x-ray (a rad is a measure of
radiation dose).
Very strict guidelines are in place to ensure that mammogram
equipment is safe and uses the lowest dose of radiation possible. Most
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 proper perspective, a woman who receives radiation
as a treatment for breast cancer will receive several thousand rads. If
that woman had yearly mammograms beginning at age 40 and continuing
until she was 90, she will have received 20 to 40 rads. For another
example, flying from New York to California on a commercial jet exposes
a woman to roughly the same amount of radiation as one mammogram.
The x-ray machine for mammography
The procedure creates 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.)
The health specialist reading the films will look for several types
of changes:
Calcifications are minute mineral deposits within the breast tissue
that appear as small white spots on the films. These calcifications may
or may not be caused by cancer. These calcifications are divided into 2
types:
- Macrocalcifications: coarse (larger) calcium deposits that most
likely represent degenerative changes in the breasts, such as aging
of the breast arteries, old injuries, or inflammation. These calium
deposits are associated with benign (non-cancerous) conditions and
do not require a biopsy. Macrocalcifications are commonly found in
about half the women over the age of 50, and in about 1 in 10 women
younger than 50.
- Microcalcifications: these are tiny specks of calcium in the
breast. These calcium deposits may appear alone or in clusters.
Microcalcifications that are seen on a mammogram are of more
concern, but do not always mean that cancer is present. In most
situations, the presence of microcalcifications does not mean a
biopsy is needed. Instead, a health specialist may advise you to
have a follow-up mammogram within 3 to 6 months. In a number of
cases, if the microcalcifications look more suspicious a biopsy is
needed.
A round mass, which may occur with or without calcifications, is
another important change seen on mammograms. The existence of this mass
can be due to many things, including cysts (non-cancerous, fluid-filled
sacs) and non-cancerous solid tumors (such as fibroadenomas).
- A cyst can't be diagnosed by physical exam alone, nor can it be
diagnosed by a mammogram alone. To verify that a mass is really a
cyst, either breast ultrasound or removal of fluid (aspiration) with
a thin, hollow needle is needed.
- If a mass in the breast is not a simple cyst (that is, if it is
at least partly solid), then you may need to have more imaging
tests. A number of masses can be watched with periodic mammograms,
while others may need a biopsy. Size, shape, and margins (edges) of
the mass itself help the radiologist to determine whether cancer may
be present.
Mammograms may show something suspicious, but by itself it cannot
prove that an abnormal area is cancer. If it raises a suspicion of
cancer, a small amount of tissue must be removed and examined under a
microscope. This procedure of examining the removed tissue is called a
biopsy. |
