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...

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...

Radiation Risks of Mammography

The risks associated with routine mammographic screening which have received the most attention are those concerned with the possible induction of breast cancer by the low-energy radiation associated with mammography, and these are the risks discussed in detail in this Section. However, it must be remembered that there are other and likely more important costs of mammography including the psychological and physical (due to surgical intervention) effects on women with FP diagnoses (Feig, 2004),...

Magnetic Resonance Imaging

Magnetic resonance (MR) imaging (MRI) is a noninvasive technique that uses the interaction between the magnetic properties of nuclei and radio waves to portray the structure of biological tissues (Damadian, 1971 Lauterbur, 1973). When placed in an external magnetic field and exposed to radio waves of proper frequency, the hydrogen nuclei within body tissues resonate i.e., can absorb energy from a tuned radio wave and then, after a delay (relaxation time) emit the energy back at the same...

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...

Screen Film Combination

Radiology Intensifying Screens

The goal in screen-film mammography for mass screening and diagnosis is to produce consistently high-contrast, high-resolution, low-noise images at the lowest radiation dose consistent with these image-quality requirements. In recent years, there have been many significant technologic improvements in mammographic screen-film combinations AAPM, 1990 Haus, 1991 1999b KimmeSmith, 1991 Rothenberg and Haus, 1995 Yaffe, 1990 . Until the early 1970s, direct-exposure industrial type x-ray films were...

Grid

High Transmission Cellular 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 Jost,...

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 to...

Info

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...

Transillumination

Transillumination of the breast began in 1929 with the real-time viewing diaphanoscopy of the breast by a dark-adapted examiner Cutler, 1929 . The technique was found somewhat helpful in distinguishing cystic from solid lesions and, specifically, in suggesting the diagnosis of hematoma and retroareolar intraductal papilloma. After a period of initial interest, the technique lapsed into relative obscurity, only to be revived in France in the 1950s with the recording of hard-copy images...

Anatomy

Breast Anatomy Retromammary Space

The fully-developed female breast is a well-differentiated apocrine sweat gland originating in the ectoderm that secretes milk during lactation. Each breast is cone-shaped, particularly in younger nulliparous females, extends from the sternum to the midaxillary line, and lies anterior to the pectoral muscle. A thin outer dermal layer covers a subdermal layer of adipose tissue that varies in thickness from several millimeters to 1 cm. Cooper's ligaments Figure 2.1 are strings of fibrous...