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...

Americorps Health Blog Mammography

Least quarterly, and the QC reports of the medical physicist each time a report is received. Interpreting physicians should also provide frequent and consistent feedback to all technologists about technique selection, clinical film quality, positioning and compression, as evaluated from clinical images. Acceptance testing of new mammography x-ray equipment shall be conducted by a qualified medical physicist prior to patient use. Acceptance testing should include the procedures performed by the...

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...

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...

Grid

Mammography Grids

Dedicated mammographic units should be equipped with anti-scatter grids (ACR, 1993 AHCPR, 1994). Scattered radiation can cause a significant reduction in subject contrast in mammogra-phy resulting in impaired detection of calcifications and the outlines of tumor masses. The advent of specialized mammographic grids revolutionized the radiologist's ability to evaluate dense tissue (Barnes and Brezovich, 1978 Chan et al., 1985 Dershaw et al., 1985 Egan et al., 1983 Friedrich and Weskamp, 1978...

Image Of A Mammmogram With Inadequate Compression

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

Ray Tube Horn Angle

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...