Question 1

What would be the appropriate change in mAs if the kVp were decreased by 15% and the density needed to be maintained?

Accepted Answer

Decreasing the kVp by 15% would require two times the mAs in order to maintain density.

Question 2

Reducing the area of exposure (increasing collimation) _____ image contrast.

Accepted Answer

Increased collimation (a smaller field size) reduces the amount of scatter produced by the tissue and therefore increases the image contrast because less scatter radiation reaches the image receptor.

Question 3

Which of the following changes will result in increased density with no change in contrast?

Accepted Answer

Decreasing the distance will result in increased density but will have no effect on image contrast.

Question 4

Which of the following is a destructive pathology?

Accepted Answer

Emphysema results in over-aeration of the lungs, therefore requiring reduced exposure factors.

Question 5

If barium sulfate is selected as the contrast media, it is necessary to:

Accepted Answer

Using barium sulfate for a study will require higher kVp (90 kVp or higher).

Question 6

With all other factors remaining the same, a patient with which body habitus would require the highest exposure factors?

Accepted Answer

The hypersthenic patient has a large, stocky build and will require the highest exposure factors.

Question 7

Which one of the following immobilizing devices requires an increase in the exposure technique?

Accepted Answer

Only the plaster cast requires an increase in exposure technique.

Question 8

An abdomen image is done using 66 kVp and 40 mAs. Image density is appropriate but the image has too high (short scale) contrast. Which of these exposure factors would be the best change to make?

Accepted Answer

In order to lower the contrast, a higher kVp is needed. However, since the density was appropriate, the mAs has to be reduced to maintain image density.

Question 9

Assuming all produce appropriate density images, which of the following would be the best exposure technique choice when performing a chest radiograph on an infant?

Accepted Answer

When imaging an infant for a chest radiograph, a short exposure time is critical.

Question 10

Generally speaking, what do additive pathologic conditions require?

Accepted Answer

Generally, additive conditions are harder to penetrate, requiring use of higher kVp.

Question 11

Assuming all exposure factors remain unchanged, what is the result of changing to an image receptor with a higher relative speed?

Accepted Answer

In that a higher speed image receptor is more sensitive to radiation, changing to a higher speed system without adjusting exposure factors will result in an image with increased density.

Question 12

In order to reduce patient exposure, a _____ kVp and _____ mAs should be used when possible.

Accepted Answer

Using a higher kVp and lower mAs is best because the higher kVp provides more penetration, requiring less exposure.

Question 13

A 3-year-old comes in for a hand radiograph. If the fixed kVp technique chart recommends 4 mAs for an average adult hand, how much mAs would the 3-year-old require?

Accepted Answer

For children age 0-5, 25% of the mAs indicated for adults is appropriate.

Question 14

When a radiograph needs to be repeated because it is too dark, the minimum change in mAs needed is:

Accepted Answer

When the image density is so far off that the image must be repeated, the minimum amount of change needed is to either double or halve the mAs.

Question 15

Generally speaking, what is the kVp value for a pediatric (less than 6 years old) skull compared with the adult skull?

Accepted Answer

Due to the lack of bone density, it is recommended that 15% less of the adult kVp be used for a pediatric skull.

Quiz 4: Radiographic Image Quality: Photographic Properties