Mammography is a specific type of imaging that uses a low-dose x-ray system for examination of the breasts. The images of the breasts can be viewed on film at a view box or as soft copy on a digital mammography work station. Most medical experts agree that successful treatment of breast cancer often is linked to early diagnosis. Mammography plays a central part in early detection of breast cancers because it can show changes in the breast up to two years before a patient or physician can feel them. Current guidelines from the U.S. Department of Health and Human Services (HHS), the American Cancer Society (ACS), the American Medical Association (AMA) and the American College of Radiology (ACR) recommend screening mammography every year for women, beginning at age 40.
Mammography can show changes in the breast well before a woman or her physician can feel them. Once a lump is discovered, mammography can be key in evaluating the lump to determine if it is cancerous. If a breast abnormality is found or confirmed with mammography, additional breast imaging tests such as ultrasound (sonography) or a breast biopsy may be performed. A biopsy involves taking a sample(s) of breast tissue and examining it under a microscope to determine whether it contains cancer cells. Many times, mammography or ultrasound is used to help the radiologist or surgeon guide the needle to the correct area in the breast during biopsy.
Because mammography can identify breast cancer in its early stages, cancers detected in this way are smaller and therefore more likely to be non-invasive than cancers detected by women through self-examination. They are also less likely to have spread to the lymph glands under the arm than cancers that present with symptoms.
Mammography is performed with a specialized mammography x-ray machine, to get a clear x-ray exposure and breast compression. Film processing and development are rigorously controlled to get the best image quality.
Mammography is not painful. Some women feel a light and momentary discomfort only due to the delicate pressing system for the breast, which is necessary in order to obtain clear and precise images. Mammograms are used to diagnose breast changes or abnormalities detected through breast self-exam and clinical examination, often with more than 2 views taken, and as a preventive screening for women to detect unsuspected cancer.
To visualize the internal structure of the breast, 2 x-rays are taken for each breast. These views (or projections) clearly show the structure of the breast.
Using the 2 standard projections, the craniocaudal (head-to-toe) view allows a better imaging of the central and medial (inner) breast sectors (excluding the breast tissue that extends under the arm). The mediolateral view is the more important because it shows all of the gland.
The patient will be asked to undress to the waist and stand in front of the X-ray machine. The radiographer will then position each breast in turn between two Perspex plates so that it is compressed and flattened. A brief pulse of X-ray is then used to take images of each breast. Normally two images per breast are taken on the first visit and one or two on every subsequent visit.
Some women find the experience uncomfortable and a few say it is painful but for the majority there is no more than minor discomfort. In any case, it is over very quickly.
The X-ray film will be examined and the patient will be told the results by their screening centre in about 10 days. A minority of women will be asked to return for a second mammogram either because something has shown up that requires further investigation, or because there is a technical problem with the first X-ray. Bear in mind that being recalled does not mean the patient has breast cancer.
Of every 10,000 women who have a mammogram, 500 will be recalled for assessment, 80 will need to have an operation and 60 will have cancer. This means that just over 1in 10 of the women who are recalled after the first mammogram for further investigation have cancer.
Many mammography facilities now use skin markers to help radiologists readily identify the nipple, surgical scars, raised moles, or other normal features on the breast. These markers are placed on the patient's breast skin before her mammogram and can easily be identified on the patient's resulting mammogram films. Markers may also be used to alert the radiologist to a breast abnormality that warrants close examination, such as a lump. The markers are either opaque or see-through and come in a variety of different shapes that correspond to different features on the breast. For example, the Beekley skin marker system uses a small pellet marker to indicate the nipple, a triangular marker to indicate a worrisome lump or mass, an S-shaped marker to indicate surgical scars, and a circular marker to encircle raised moles on the breast. The markers are made in such as way so they do not obscure any breast tissue.
By immediately identifying normal or worrisome areas of the patient's breast, the markers help save the radiologist time and confusion when reading the patient's mammogram film. Many physicians believe these markers are more useful than solely noting moles or other features on mammogram sketches because the shape of the breast is altered when it is compressed during the mammogram exam. Thus, the resulting films may not show a mole in the same area as noted by the technologist on a mammogram sketch. Nipple markers are especially useful because they help the technologist position the patient and verify that the nipple is in profile before the exposure is taken. The markers use adhesive similar to a Band-Aid and are easily removed after the mammogram.