There are two reasons mammograms are taken:
Screening mammograms are done for women who have no symptoms of breast cancer.
Diagnostic mammograms are done when a woman has symptoms of breast cancer or a breast lump. Diagnostic mammograms take longer than screening mammograms, because more pictures of the breast are taken.
In January 2000, the FDA approved a new way of doing mammograms, called digital mammography. This technique records x-ray images on a computer, rather than film. Digital mammography has the following advantages:
can reduce exposure to radiation
can allow the person taking the x-ray to make adjustments without having to take another mammogram
takes pictures of the entire breast, even if the denseness of the breast tissue varies