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X-RAY MAMMOGRAPHY

●What is mammography? 

Mamma is Latin for breast and mammography is a type of breast X-ray that uses only a limited amount of radiation. It can identify breast cancer in its early stages.

●What are the benefits of mammography?

Since mammography can diagnose breast cancer in its early stages, cancers detected in this way are smaller andtherefore more likely to be non-invasive than cancers detected by women through self-examination which can beextremely invasive. They are also less likely to have spread to the lymph glands under the arm than cancers that

 present with symptoms. [1]

●Technology behind: 

Equipment for mammography

has evolved over at least the

last 40 years to the currentstate of the art. While there are

some differences from one

manufacturer to another, there

are also many characteristics

and features that are common

to all.

X-ray Tube Anode: Whereas

most x-ray tubes use tungsten

as the anode material,

mammography equipmentuses molybdenum anodes or 

in some designs, a dual

material anode with an

additional rhodium track.

These materials are used

 because they produce a characteristic radiation spectrum that is close to optimum for breast imaging as described

later.

Filter: Whereas most x-ray machines use aluminum or "aluminum equivalent" to filter the x-ray beam to reduce

unnecessary exposure to the patient, mammography uses filters that work on a different principle and are used to

enhance contrast sensitivity. Molybdenum (same as in the anode) is the standard filter material. Some systems

allow the operator (or automatic control function) to select either the molybdenum or a rhodium filter to optimizethe spectrum for specific breast conditions.

Focal Spots: The typical x-ray tube for mammography has two selectable focal spots. The spots are generally

smaller than for other x-ray procedures because of the requirements for minimal blurring and good visibility of 

detail to see the small calcifications. The smaller of the two spots is generally used for the magnification

technique.

Compression: Good compression of the breast is one of the essentials of effective mammography (and a

common source of patient discomfort and concern). Potential benefits derived from compression include:

1.  A more uniform breast thickness resulting in a better fit of the exposure into the film latitude or 

dynamic range.

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2.  Reduced blurring from patient motion.

3.  Reduced scattered radiation and improved contrast sensitivity.

4.  Reduced radiation dose.

5.  Better visualization of tissues near the chest wall.

Grid: A grid is used in mammography (as in other x-ray procedures) to absorb scattered radiation and improve

contrast sensitivity. Compared to grids for general x-ray imaging, grids for mammography have a lower ratio and

the material between the strips is selected for low x-ray absorption.

The grid is contained in a Bucky device that moves it during the x-ray exposure to blur and reduce the visibility

of the grid lines.

Receptor: Both film/screen and digital receptors are used for mammography. Each has special characteristics to

enhance image quality and will be considered later. [2]

●How does the procedure work?

X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body.

Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of 

radiation that passes through the body, recording an image on photographic film or a special detector.

Different parts of the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while

soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones

appear white on the x-ray, soft tissue shows up in shades of gray and air appears black.

Until recently, x-ray images were maintained as hard film copy (much like a photographic negative). Today,

most images are digital files that are stored electronically. These stored images are easily accessible and arefrequently compared to current x-ray images for diagnosis and disease management. [3]

REFERENCES:

[1] http://www.netdoctor.co.uk/health_advice/examinations/mammography.htm [2] http://www.sprawls.org/resources/MAMMO/module.htm

[3]http://www.radiologyinfo.org/en/info.cfm?pg=mammo

Özge Çolak