RAD 350 Chapter 23 Mammography
Breast cancer is second only to lung cancer for the leading cause of death in women. One in
eight women ill develop breast cancer.
“Soft tissue” imaging/mammography is instrumental in the detection of breast cancer at
early stages.
For many years, mammo was done with direct exposure film and cardboard film holders.
This was done in order to differentiate the very similar effective atomic numbers and atomic
mass densities in the three PRIMARY types of breast tissue. The 1960’s saw
“xeroradiography” or xeromammography whereby an image was made via much lower mAs
technique and the images processed similar to a copy machine process (they used blue
tinted toner on paper for the images). One of the biggest drawbacks to this process that
improved detail and contrast was the toner and dust artifacts that frequently occurred.
In the 1990’s new single intensifying screen/film combination made for equal or lower mAs
techniques with excellent detail and contrast. Single emulsion and screen techniques are
used to eliminate the “cross over” imaging that can occur with two screens and double the
emulsion film (thus the “low dose mammo” as advertised by most imaging centers today).
Mammography is highly regulated by the federal government in that radiation is a prime
CAUSE of breast cancer. In the late 80’s and early 90’s the ACR and the “Feds” mandated
Mammography Quality Standards Act (MQSA).
There are two basic types of mammograms done today: screening (a two view study, which
includes a baseline mammogram usually around age 40) and diagnostic (a three view study)
for symptomatic patients or thgose with breast implants.
Box 23-1 shows the risk factors for breast cancer
Age: the older, the higher the risk
Family history: mother, sister with breast cancer
Genetics: BRCA1 or BRACA2 genes (expensive tests, not covered by insurance)
Menstruation: onset prior to age 12
Menopause: onset after 50
Prolonged use of estrogen
Late age of birth of 1st child or NO children
Socioeconomics: risk increases with higher status
TABLE 23-1 Shows the age and intervals of various breast examinations
Breast tissue is made up of three primary tissue types: fibrous, glandular and adipose.
Premenopausal women have a much MORE DENSE (required MORE mAs) breast consisting
of the fibrous and glandular tissues (glandular is the MOST sensitive breast tissue to
radiation!) surrounded by and structured into various ducts, glands and connective tissues.
Postmenopausal breasts are LESS dense as they have more adipose tissue with decreased
fibroglandular tissue.
About 80% of breast cancers are DUCTAL and many have “Microcalcifications: surrounding
and inside the tumor mass.
Since the breast tissue is low atomic mass number, LOE kVp techniques are used (usually in
the 23-28 range). NOTE: MANY sources will give MANY kVp ranges – you will be safe to think
of mammo kVp’s in the 20-30 kVp range.
The target of mammo tubes is usually made of tungsten (W), molybdenum (Mo) or rhodium
(Rh). This combination will result in higher quality beams due to the characteristic beam
emission spectrum. DO NOT spin your wheels on memorizing target and filet material
matches, just be aware they MUST be matched in mammo tubes. Also the min. of 0.5 mmal
equivalent added filtration is required.
The heel effect is ALWAYS utilized in mammo! ALSO compression of the breast is done to
improve SPATIAL RESOLUTION! It also reduces motion blur, separates overlying tissues,
provides a more equal optical density, improves contrast and reduces patient dose.
Compression should NEVER exceed 40 pounds of pressure in the automatic mode!
Mammo usually uses either 4:1 or 5:1 FOCUSED grids.
Magnification mammo views are sometimes requested to enhance the microcalcifications as
well as delineate the ductal pattern distortion frequently found in tumor tissues.
The ONLY image receptor types used today are : screen-film and digital detectors. Digital
mammo has recently been approved to be done without film back up. The chief advantage
of digital mammo is the ability to post image acquisition “tweak” the image for greater
contrast resolution.