Mammography Questions and Answers Roland Wong, Sc.M., D.A.B.M.P

MammographyQuestions and Answers

Roland Wong, Sc.M., D.A.B.M.P.

RAPHEX Diagnostic Question 2001

D17: Which of the following is not an advantage of good compression in mammography?

A. Reduced patient motion blur.B. Reduced geometric blur.C. Reduced scatter.D. Reduced average glandular dose.E. Increased magnification.

RAPHEX Answer to 2001 Question D17

E. A-D are advantages of good compression, bur magnification decreases since patient to image receptor distance decreases.


D18: The main reason the kVp in mammography is increased for thicker breasts is to:

Reduce average glandular doseB. Improve contrastC. Reduce scatterD. Reduce exposure timeE. Reduce focal spot size


D. Reduce exposure time.Although the AGD is decreased by raising the kVp, the main reason for increasing kVp is to reduce exposure time, and hence motion blurring. The rule of thumb is to try to keep the exposure time between 1 and 2 sec.


D19: Ideally, the AEC (phototimer) sensor in mammography should placed:

A. As close to the chest wall as possibleB. Under the densest portion of the breastC. Under the least dense portion of the breastD. Under the most anterior portion of the breastE. In the center of the breast


B. Under the densest portion of the breast.

Placing the AEC sensor under the densest portion will reduce problems with underpenetration. All portions of the image should have an OD above 1.0. Reviewing previous films helps to position the sensor.


D20: Subject contrast in mammography is affected by:

A. Beam filter choice

B. Focal spot size

C. AEC density setting

D. Exposure time

E. Film processing conditions

RAPHEX Answer for 2001 Question D20

A. Beam filter choiceOnly changes in x-ray beam and scatter affect subject contrast. The other items affect film contrast. Focal spot size has no effect on contrast.


D29: Which of the following is NOT true? Vigorous compression in mammography reduces:

A. Patient doseB. ScatterC. Motion unsharpnessD. Subject contrast


D. Subject contrast

Compression improves subject contrast by reducing scatter.


D30: The filtration in mammography units primarily transmits the characteristic x-rays. It is desired to filter out the very low-energy bremsstrahlung x-rays because they contribute to _____, and it is desired that the higher energy bremsstrahlung x-rays be filtered because they contribute to ______.

A. tube heating, off-focus radiation

B. heel effect, focal spot blooming

C. radiation dose, loss of contrast

D. grid cut-off, septal penetration

E. coherent scatter, K-edge photons


C. radiation dose, loss of contrastMost low-energy x-rays do not reach the film, and only contribute to absorbed dose. Therefore, we wish to fllter these x-rays out before they reach the breast. The higher energy x-rays are less likely to undergo photoelectric interactions which are the source of the image contrast, while Compton scattering (which reduces contrast) remains the same.

In mammography, the x-ray beam filtration is usually the same material as the anode, with the highest attenuation occurring just above the energy of the K-characteristic x-rays. Thus, x-rays (bremsstrahlung) above this energy are selectively absorbed.


D32: Calcifications are seen In mammograms because of their ________.

A. Atomic number

B. Density

C. Electrons/gram

D. Size

E. Location


A. Atomic number.At the low x-ray energy used in mammography, the interactions are predominantly photoelectric. Thus attenuation (and hence contrast) is proportional to Z3. The Z of calcium is 20, while the effective Z of fat and breast tissue is between 6 and 8.


D31: In mammography, average glandular tissue dose depends on:

A. Breast compression

B. Breast thickness

C. kVp

D. mAs

E. All of the above


E. All of the above.Average dose of the glandular tissue is an indicator of the risk of carcinogenesis. The dose depends on the energy distribution in the incident x-ray beam (kVp, HVL), mAs, and compressed breast thickness.


D33: In mammography the ACR recommends a compression force of 25-40 pounds. This will result in:

A. Reduced geometric unsharpness

B. Contrast improvement

C. Reduced radiation dose

E. All of the above


E. All of the above.Good compression moves the breast tissue

closer to the film, reducing geometric unsharpness from the focal spot.

It also reduces the breast thickness near the chest wall, resulting in less scatter and better contrast, and a lower radiation dose.

Compression also prevents movement, reducing motion unsharpness.


D28: Which grid would be the best choice for use as a stationary grid in mammography?

A. 44 line/cm, 5:1 ratio

B. 44 line/cm, 12:1 ratio

C. 80 line/cm, 5:1 ratio

D. 80 line/cm, 12:1 ratio

E. Any of the above, as long as they are made of carbon fiber


C. High line/cm are needed for the stationary grid so the grid lines are not visible. A 5:1 grid ratio is appropriate for mammography because thesmall scattering volume and low kVp cause relatively little scatter.

Carbon fiber is a good material with low attenuation for grid covers and interspacing. However, there are also good mammographic grids that use other types of fiber or wood.


D34: In order to limit the loss of spatial resolution due to geometric unsharpness, the measured focal spot size for screening mammography should be less than _____ mm.

A. 2.0

B. 1.0

C. 0.6

D. 0.3

E. 0.15


C. 0.6

See NCRP Report 85: “Mammography – A User’s Guide”


D29: The following film processor parameters all affect mammography image quality EXCEPT:

A. Nitrate depletionB. Developer concentrationC. Developer temperatureD. Replenishment ratesE. Developer immersion time


A. Nitrate depletionB-E directly influence the density and speed of the various film/screen systems. Although bromine concentration in the developer affects both speed and contrast, nitrate depletion has no effect on the development of mammography films.

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Mammography Questions and Answers Roland Wong, Sc.M., D.A.B.M.P