2 Mammography Grid Styles

The grid, placed between breast and image receptor, absorbs scattered x rays and improves contrast (Figure 2.31), enabling the border of the glandular tissue to appear more crisply defined. Even so, the grid does not eliminate the need for firm compression, which spreads the tissue apart and permits the borders of small lesions to be perceived (Figure 2.32). The breast should be compressed as firmly as the patient permits. Previously, many radiologists used the grid only for patients with dense...

Q

To the CC view for the routine, two-view mammographic study. In the MLO view, the technologist rotates the C-arm so that the image receptor is parallel to the fibers of the pectoral muscle. She places the imaging system midway between the inferior and the lateral aspect of the breast (the lower outer quadrant), and directs the radiographic beam through the breast from superomedial to inferolateral. Screen-film mammography has a narrow recording latitude. Moreover, screen-film mammography...

Glossary

This glossary is adapted from ACR (1999) with permission, AHCPR (1994), and other sources. abnormal screening examination Mammography examination resulting in the recommendation of further imaging evaluation, short-interval follow-up or biopsy. absorbed dose (D) The energy imparted to matter by ionizing radiation per unit mass of irradiated material at the point of interest. The special name for the unit of absorbed dose is the gray (Gy), where 1 Gy aliasing The false frequency information (or...

Usefulness of Mammography for Breast Cancer Screening

There is little, if any, opposition to the practice of diagnostic mammography, probably because of the compelling clinical need for the information obtained. Many mammography examinations are performed for diagnostic purposes, and mammographic screening programs have also been widely implemented. There has been some opposition to screening in the past for a variety of reasons (1) concern over a few published indications of a relatively unfavorable benefit risk ratio, (2) concern about exposure...

Ultrasound

Ultrasonography employs mechanical energy (sound) rather than electromagnetic radiation to produce a pictorial representation of the internal structure of the breast. The image is produced by transmission of sound pulses into the breast and measurement of the returning echoes at later times, depending upon the depth of interfaces between different tissue types. The transducer functions as both transmitter and receiver. An attractive feature of sono-graphic imaging is that there are no known...

Ray Unit

While a variety of x-ray units have been used in mammography since its inception (Bassett et al., 1992 Gold, 1992 Vyborny and Schmidt, 1989), it is now widely recognized that quality mammog-raphy requires a dedicated mammographic x-ray unit (ACR, 1993 DHHS, 1987 Haus, 1990 Yaffe, 1991). In order to meet the stringent imaging needs of mammography such a unit must be equipped with a variety of essential features discussed in this Section. These include a small focal spot coupled with a relatively...

Other Breast Imaging Modalities

Among the various imaging methods designed to evaluate the breast for cancer, conventional mammography is the most accurate and most widely used. It has gained clinical acceptance for screening because it may depict a cancer often before the tumor mass becomes large enough to be palpable. Conventional mammography is valuable in helping to distinguish benign from malignant lesions, facilitating prompt biopsy of cancers, while encouraging clinical management of many benign breast lesions. Digital...

Quality Assurance

Quality assurance (QA) in mammography is defined as those planned and systematic activities that monitor and improve the early detection of breast cancer and the evaluation of breast disease. Those activities include the employment, training, and continuing education and experience of qualified personnel. They also include the selection of appropriate mammography equipment, acceptance testing and regular evaluation of equipment performance, and the evaluation of positioning and compression. QA...

Image Of A Mammmogram With Inadequate Compression

Miss Calcification Mammography

This 37 y old woman's calcifications are not as identifiable on her left CC nongrid mammographie view (A) as they are on the same projection with the grid (B). Fig. 2.31. This 37 y old woman's calcifications are not as identifiable on her left CC nongrid mammographie view (A) as they are on the same projection with the grid (B). Fig. 2.32. With firm compression, the small cancer (arrow) is obvious on this CC-view mammogram (A), because compression displaces the islands of glandular...

Half-field Geometry In Mammography

Perpendicular Mammogram

Therefore, in order to compare measured and nominal focal-spot sizes, the measurement made at the chest wall needs to be corrected to estimate its size at the reference axis. The reference axis usually bisects the angle formed by the x-ray tube target and the ray perpendicular to the image receptor at the chest-wall edge of the image receptor . Thus, for an x-ray tube with an effective target angle of 22 degrees target angle of 16 degrees plus a tube tilt of six...

Molybdenum In Mammography

Molybdenum and Rhodium Energy Spectra Fig. 4.2. Typical x-ray emission spectra used in screen-film mammography. For the molybdenum Mo target, a 0.03 mm molybdenum filter is used and a 26 kVp setting is shown solid line . For greater penetration, a rhodium Rh filter can be used as shown here dotted line . For very dense breasts, a Rh target and Rh filter x-ray source operated at 30 to 32 kVp may be useful. The dominant characteristic x-ray peaks Ka occur at 17.4 keV for a molybdenum target and...