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How Mammography is Performed: Imaging and Positioning

Notice: Revised breast cancer screening guidelines issued in November 2009.

This article illustrates how different mammography views are taken, and how the patient should be positioned to achieve optimal mammogram images. The information presented in this section is intended for mammography technologists, healthcare professionals, and patients interested in learning more about mammography imaging and positioning.

All images are courtesy of Siemens Medical, and captions are based on information from the Siemens "Mammography Applications" handbook. The information herein is intended for mammography performed with the Mammomat 3000/300 and 3000/1000 Nova but can also be used as a general guideline for mammography performed with other mammography systems. Because each case is unique, different patients may require different mammography views, etc.

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Brief Overview of Mammography

Mammography is currently the only exam approved by the U.S. Food and Drug Administration (FDA) to help screen for breast cancer in women who show no signs of the disease. A screening mammography is every one to two years is recommended for in their forties. Women in their 50s should receive screening mammograms every year. Screening mammography typically involves taking two views of the breast, from above (cranial-caudal view, CC) and from an oblique or angled view (mediolateral-oblique, MLO). Diagnostic mammography may be performed to examine an abnormality detected by screening mammography or physical exam. Diagnostic mammography may involve taking supplemental view tailored to the specific problem. These may include views from each side (latero medial, LM: from the side towards the center of the chest, and mediolateral view, ML: from the center of the chest out), exaggerated cranial-caudial, and other special views such as spot compression and magnification views. If an abnormality is detected with diagnostic mammography, follow-up may include additional breast imaging, such as ultrasound, or biopsy.

Mediolateral Oblique View (MLO)

The mediolateral oblique view (MLO) is taken from an oblique or angled view. During routine screening mammography, the MLO view is preferred over a lateral 90-degree projection because more of the breast tissue can be imaged in the upper outer quadrant of the breast and the axilla (armpit).

This illustration shows the angled or oblique MLO view and the cranial-caudal view (CC), which is taken of from above.

 

With the MLO view, the pectoral (chest) muscle should be depicted obliquely from above and visible down to the level of the nipple or further down. The shape of the muscle should curve or bulge outward as a sign that the muscle is relaxed; the medial (middle) portion of the breast should be prominent in the MLO view. It is important that compression be applied over the whole image area. The nipple should be depicted in profile and a small stomach fold should be visible as a sign that the whole breast is reproduced.

Positioning a patient for an MLO view:

#1: To take an MLO view, the mammography technologist will set the angle for the desired projection (30 degrees to 60 degrees). The object table is the platform that supports the breast and holds the film cassette or digital detector. The object table should be parallel with the pectoral (chest) muscles, and the top edge of the table should be level with the axillary (armpit) fold.

 

#2: During an MLO view, the patient should stand stead at a 45-degree angle to the mammogram stand. The technologist will instruct the patient to lift her elbow while keeping her hand firmly on the machine’s handle. The patient will bend slightly forward, and the technologist will take hold of the lifted arm and breast from below, drawing the medial (middle) portion of the breast forward. The technologist will then apply compression while holding the patient’s collarbone (clavicle) so that the compression plate is just clearing the collarbone. When the compression is sufficient, the technologist will make sure nothing is blocking the field of the intended image.

 

#3: When the patient has been properly positioned, the technologist will ask her to stand absolutely still and then leave to make the exposure.

Cranio-Caudal View (CC)

The cranio-caudal view (CC) images the breast from above. This view may be taken during routine screening mammography and during diagnostic mammography.

This illustration shows the cranio-caudal view (CC) and the mediolateral oblique view, which is taken from an oblique or angled view.

 

With the CC view, the entire breast parenchyma (glandular tissue) should be depicted. The fatty tissue closest to the breast muscle should appear as a dark strip on the x-ray and behind that it should be possible to make out the pectoral (chest) muscle. The nipple should be depicted in profile.

Positioning a patient for a CC view:

#1: For the CC view, the mammography technologist will lift the breast approximately two centimeters and adjust the height so that the object table touches her hand.

 

#2: The technologist will stand on the medial side of the breast that will be x-rayed (or behind the patient) and ask the patient to turn her head toward her. Then, the technologist will take hold of the patient’s back and shoulder in order to press her closer to the table. With her other hand, the technologist will take hold under the breast from its sides and lay it on the table, drawing the breast somewhat toward her so that the lateral (outer) side is turned forward.

 

#3: The technologist will apply compression while making sure there are no folds on the lateral side. She will put her hand on the patient’s shoulder to stretch the skin, ensuring that nothing blocks the x-ray field. When the compression is sufficient, she will ask the patient to stand absolutely still and leave to make the exposure. Click on image to view larger version.

Medio-Lateral View (ML)

The medio-lateral view (ML) is taken from the center of the chest outward. If no oblique projection is taken, the mediolateral position may be preferable to the latero-medial view (LM, images the breast from the outer side of the breast inward toward the center of the chest) since the lateral side of the breast, where pathological changes are most commonly found, is then closest to the film. However, if the physician wants to include as much of the medial side of the breast as possible, the LM view may be chosen.

This illustration shows the ML view, which images the breast from the medial side (the "middle") outward.

 

With a lateral view, the pectoral (chest) muscle should be depicted as a narrow light band on at least half of the picture. The nipple should be depicted in profile and a clear stomach fold should be visible under the breast.

Positioning a patient for an ML view:

#1: For the ML view, the mammography technologist will set the x-ray tube in a 90-degree lateral projection, ensuring that the correct slide marker is used.

 

#2: The technologist will set the height to the axillary (armpit) fold and ask the patient to put her arm along the object table and stretch it forward. While grasping the breast from below and drawing it out, the technologist will apply compression with one hand and place her other hand on the patient’s back, pressing her toward the stand. If the other breast blocks the field, the technologist may help the patient keep it out of the way. In some cases, a wide paper plaster may be used to hold the other breast away. The technologist may attach the plaster from the patient’s sternum and fix it, after drawing the breast back, onto the patient’s back.

 

#3: When the compression is sufficient, the technologist will ask the patient to remain absolutely still. Then she will leave to make the exposure.

Latero-Medial View (LM)

The latero-medial view (LM) images the breast from its outer side toward the center of the chest. When physicians want to include as much of the medial portion of the breast, the LM view may be used.

This illustration shows how the LM view is taken, from the outer side of the breast inward.

 

#1: For the LM view, the mammography technologist will set the tube in a 90-degree projection, ensuring that the correct slide marker is used. She will set the height to the uppermost point of the sternum, positioning the patient with the object table between her breasts.

 

#2: The technologist will ask the patient to lift her arm and place her hand on the handle while keeping the elbow lifted. She will then ask the patient to place the point of her chin as far forward as possible on the edge of the object table. Grasping her breast from below and drawing it outwards, the technologist will apply compression, pressing the patient toward the table (taking care to ensure that the patient’s arm is not squeezed).

 

#3: The technologist will ensure that nothing blocks the x-ray field and that the patient is at ease. After instructing the patient to stand absolutely still, the technologist will leave to make the exposure.

Additional Resources on Mammography

Follow the links below for in-depth information on mammography.

References

  • "Mammography Applications," is a publication of Siemens Medical Systems, Siemens-Elema AB, Division SPS: Feb. 1999; Solna, Sweden.

Updated: November 28, 2009