A
diagnostic mammogram is essentially a low dose X-ray of the breast which has
been used for screening since the 1980s.
How
does mammography work?
For
a short time the breast is compressed into two different positions and then X
rays of the breast are taken. This examination takes about 10 minutes and
sometimes a radiologist may require additional images in order to include all
the breast tissue completely. Due to the compression the amount of radiation
required to penetrate the tissue is reduced and the breast tissue is spread out
which enhances the quality of images. Due to compression
the motion is also reduced which prevents the image from getting blurred and
also prevents important findings to be missed. In a mammogram you can see
cancers as masses, areas if tissue asymmetry, calcifications and/or areas of
distortion. However, skill is required to study mammograms because many
noncancerous conditions also produce masses and calcifications and normal
tissues can also appear as areas of asymmetry. At the same time, a mammography
is unable to differentiate between normal and cancerous tissues in cases of dense
breast tissue.
Mammography
is of two types – 2D mammography and 3D mammography. 2D mammography is also
known as Full Field Digital Mammogram or analog mammogram.
3D mammogram is also known as
tomosynthesis or tomo.
In this method a dedicated electronic detector system is used to obtain
multiple projection images which are then synthesized with the help of the
computer to create thin slices of the breast.
In
this method specially equipped digital mammography machines are used to acquire
images at multiple angles. Here again the breast is compressed to get better
quality of images and reduce the amount of radiation required. The benefit of
this method is that when combined with standard digital mammography, tomo is
able to reveal 1 to 2 additional cancers per thousand women in the first round
of screening.
