Mammograms are breast x-rays, which usually include ≥ 2 views of each breast taken at different angles. The breasts are compressed with plastic paddles to optimize visualization of breast tissue and abnormalities.
Screening mammograms are used to check for breast cancer in asymptomatic women (see Breast Cancer, Screening Screening Breast cancers are most often epithelial tumors involving the ducts or lobules. Most patients present with an asymptomatic mass discovered during examination or screening mammography. Diagnosis... read more 
).
Diagnostic mammograms are used to diagnose breast disorders in women who have
Breast symptoms
Palpable breast masses
Abnormal results on screening mammograms that require further investigation
Diagnostic mammograms can include standard and specialized views.
Typically, mammography exposes the breasts to about 0.4 mSv of radiation. This dose is relatively low compared with other imaging tests that use radiation (see table Typical Radiation Doses Typical Radiation Doses* 
). However, radiation exposure is a concern with mammography because breast tissue is sensitive to radiation (see Risks of Medical Radiation Risks of Medical Radiation Ionizing radiation (see also Radiation Exposure and Contamination) includes High-energy electromagnetic waves (x-rays, gamma rays) Particles (alpha particles, beta particles, neutrons) Ionizing... read more ). Mammography is sometimes recommended only for women > 40 partly because breast tissue in older women is less sensitive to the adverse effects of radiation. Specialized mammography units and digital imaging techniques are used to minimize radiation exposure.
Variations of mammography
Tomosynthesis, a 3-dimensional technique, can be used in mammography. In tomosynthesis, an x-ray source moves over an arc of excursion, providing thin, tomographic slices, which are reconstructed into 3-dimensional images. This technique minimizes the effect of overlapping structures in the breast. Thus, abnormalities can be better separated from the background. As a result, the need for repeat mammograms may be reduced, and clinicians may be able to detect cancers more accurately, especially in patients with dense breasts.
The total radiation dose used in 3-dimensional mammography (1.0 mSv) is higher than that used in conventional mammography (0.5 mSv), although it is relatively low, compared with some other imaging tests.
