The increased emphasis on mammography has been accompanied by advances in the X-ray equipment and techniques used to reduce radiation exposure. For example, the senograph, developed in France, is a mammography machine with a special X-ray tube and filters. The special combinations of films and screens deliver minute amounts of radiation— a total of .02 to .03 rads to the mid breast for two views.
One special form of mammography is called xeromammography, developed by the Xerox Corporation. It produces a positive image (as opposed to a negative X-ray film) on a Xerox plate, but requires a slightly higher dose of radiation than conventional mammography. Even so, it is an excellent technique that some radiologists feel produces results that are easier to interpret.
The Examination Itself
Mammography is usually done in a radiology laboratory, diagnostic clinic, doctor’s office, or hospital outpatient clinic. It takes about a half-hour to complete. Clothing and jewelry above the waist are removed, and women should avoid using talcum powder or skin creams on their breasts just prior to mammography as these may appear as suspicious signs on an X-ray film. During the actual mammographic examination, a woman is positioned so that one breast is resting on a plate above an X-ray cassette.
A clear plastic shield may be used as a compression device to somewhat flatten the breast against the plate. Two views are taken of each breast—one from the side and the other giving a top-to-bottom view. While the woman waits, the X-ray films are developed to make sure that they are readable. They will later be interpreted by a radiologist who is experienced in reading mammographic films. In general, cysts show up as clear spots, with well-defined, regular outlines. They may be multiple and may be present in both breasts. In contrast, breast cancer usually appears as irregular, opaque areas with poorly defined edges. It should be emphasized that a mammogram only pinpoints suspicious areas; a definitive diagnosis is reached only by biopsy.