WHAT IS A MAMMOGRAM?
A mammogram is a radiograph of the breast tissue (refer to
the attached copy of a mammogram). It is an effective
non-invasive means of examining the breast, commonly searching
for breast cancer. Cancer is not preventable, but early
detection leads to a much higher chance of recovery and lowers
the mortality rate from this disease.
composition varies with age and hormone levels in a woman.
- A younger woman has
denser or fibro-glandular breasts. Her mammogram will look
very white or "cloudy" (Figure 8-dense breast).
- Middle-aged women
have a mixture of fibrous and glandular tissues (Figure
8-50-50 breast). Their mammograms look black and white.
- In a mature breast,
most of the fibrous tissue is replaced with fatty tissue. The
mammograms tend to look black or gray (Figure 8-Fatty Replaced
18 x 24 cm used for small to average sized breasts and
24 x 30 cm used for large sizes.
Here is what happens, in brief :
- The woman is
escorted to the changing room, where she undresses from the
waist up and changes into the screening center gowns
- She is asked to wipe
off any deodorants, perfumes or powders that she may have used
that day, as these can mimic micro calcifications on the film
- She is taken into
the mammography room, where the mammographer or technologist
reviews her history sheet. The history sheet has questions
pertaining to the woman’s previous mammograms, prior surgeries
(if any), if she felt any lumps, superficial marks (such as
prominent moles, scars from an incision), family history of
breast cancer, number of children, her age when the first
child was born, and last date of menstruation or
post-menopausal (Addendum 2). Then, the mammography procedure
is explained. This opens communication channels and the woman
feels free to voice her concerns, thus increasing her comfort
- It is important to
prepare the woman for the compression that would be used for
imaging. This device causes discomfort, but should not hurt
the woman. A Compression Paddle, (see Figure 6 and Figure 7)
is a device used to compress the breast tissue. This helps to
spread out and separate breast tissue, enabling the
Radiologist to get an unobscured view of possible pathology.
Compression also lowers patient radiation dose and prevents
- The required views
are performed and the woman is dismissed with instructions
that she might feel sore for a day or so from the compression.
equipment has progressed rapidly over the last 10 years. In
developed countries, a dedicated mammography unit is used. A
whole range of manufacturers make these machines, for example
: GE, Bennett, Lorad, Siemens, Fischer, Phillips. They
generally have a reciprocating grid to reduce scatter
radiation thus avoiding fog and blurry image. The Filter (to
make the beam hard and more penetrable) used, is 0.03 mm
Film Processing is done
under specific conditions. The two ways to develop an exposed
film are (1) Standard Processing and (2) Extended Processing.
The choice depends on the type of film used.
- Technique used for a
mammogram is low Kilo-voltage Peak (KvP) about 24 to 30. The
milli-Ampere-seconds (mAs) varies depending on breast tissue
density. When the photo timer cells are used, it provides the
optimum mAs for the tissue to be imaged. This technique
results in mammograms with a high film contrast, making it
easier for the Radiologist to read.
- The Films used for
mammography are single emulsion fast films to enhance image
sharpness by eliminating geometric distortion. Films commonly
used are : Kodak Min- RE, Agfa, Fuji, Dupont, Konica.
- The screens consist
of a rare earth phosphor called terbium activated gadolinium
oxysulfide. Screens have to be compatible with the film. The
newest film-screen combination is responsible for dose
reduction by 30 - 50 % .
- Markers are used to
indicate the side and view demonstrated on that particular
film. Markers are placed on the side of the axilla (armpit) of
the patient. This acts as a reference point to understand the
orientation of the breast, especially in the CC view.
These views are done as a regular screening process to get an
overall picture of the breasts and ensure that all is well. The
protocol depends on the specific facility. In America, four
films are required of the breasts: two views for each breast.
In Europe, most
countries do one view (MLO) of each breast and if an area of
suspicion is notice, then 15% of the times, additional CC views
head (cranium) to the feet (caudal)
||X-ray direction is
from medial(inner) to lateral (outer) aspect; and the
orientation of the breast is at an angle (Oblique)
These are views done when the patient is unable to be positioned
in certain views due to physical handicap or when the
Radiologist wants to get a better look at possible pathology.
||Direction of ray
is from lateral(outer) to medial (inner), obliqued breast to
demonstrate lesions in medial area
|90 degree Lateral
||Direction of ray
from one side to the other and the breast is in the lateral
Regular views done and additional "Implant Displaced" (ID) Views
performed. Regular views comprise of the screening views with
minimal compression (too much compression can damage the
implants) and ID views are the screening views with the implants
pushed back against the chest wall and focus is on breast tissue
These views are to be used in addition to the screening
mammograms to localize the exact position of an abnormality or
views to better define the nature of an abnormality. Some
abbreviations for those views are:
||Cranio Caudal view
eXaggerated to axilLa
||Cranio Caudal view
Reading mammograms is a challenge for Radiologists. Diagnosis is
truly subject to interpretation. Hence the concept of a ‘second
reader’ is catching on in USA. In Europe, a second reading is
routine procedure. A powerful magnifying glass is used to get a
better look at suspected pathology. The ideal reading condition
is in a dark room with no lights other than the ones from behind
the mammogram films (on a film viewer or a motorized film
viewer). Usually, in the reading area, there is a ‘hot light’
which is more powerful, enabling the Radiologist to get a
sharper view of suspected area. If required, the Radiologist can
turn this on and hold the film in front of it.
Radiologists read films
as per certain criteria :
- They do a
comparative study of current films and prior films. They look
for tissue, structure and calcification changes. If for
example, they see that the current films have more
microcalcifications than the previous, the woman would be
subject to additional views in order to visualize the
- The Radiologists
also do a comparative study of both the breasts. This is
termed as an ‘ asymmetric study’. Generally, pathology does
not occur in the both the breasts asymmetrically.
- Viewing the
parenchymal pattern is another method used by many
Radiologists to find some signs leading to the detection of
small invasive tumors. Both the CC views are placed against
each other and they look for asymmetry, which is indicative of
tumors. Similarly, both the MLOs are compared. Other features
they look for are: architectural distortion, comparison of the
nipples and retroareolar areas.
If the Radiologist detects an area of suspicion, a series of
work-up procedure is recommended. The criteria for their
decision is based on what they see and the location.
For example, in the
course of ‘asymmetric study’ the Radiologist discovers a
density, then he/she has to decipher if the pathologic
abnormality is obvious (stellate lesion, typical/linear
cancerous microcalcifications). If the answer is ‘Yes’, various
procedure and modalities could be used (core biopsy or
ultrasound), if it is ‘No’, then additional views such as spot
compression can be performed to see if see if the density is an
architectural distortion, fibrosis or normal parenchyma.
Here is a table of
‘Protocol for Breast Cancer Screening Path’ :