Ch. 27 Contrast (Exp I)

Question 1

The recorded detail of a radiographic image is visible because of:

Answer 1

• Sufficient contrast

- Sufficient density

Question 2

The difference between two adjacent densities is:

Answer 2

Radiographic contrast

Question 3

A radiograph with few shades of gray exhibits:

Answer 3

High contrast

Question 4

Which type of radiograph provides the most information?

Answer 4

Low contrast images

Question 5

The principal controlling factor of contrast is:

Answer 5

kVp

Question 6

A radiograph that demonstrates considerable differences between densities is called:

Answer 6

• Short scale
• High contrast
• Increased contrast

Question 7

A radiograph that demonstrates minimal differences between densities is called:

Answer 7

• Long scale
• Low contrast
• Decreased contrast

Question 8

A radiograph that demonstrates considerable differences between densities is called:

Answer 8

High contrast

Question 9

A radiograph that demonstrates minimal differences between density shades is called:

Answer 9

Low contrast

Question 10

Image receptor contrast is expressed as the _____ of the D log E curve.

Answer 10

Slope

Question 11

Contrast decreases with:

Answer 11

• Excessive density
• Inadequate density
• A wider range of densities

Question 12

As the slope of the D log E curve _____, contrast _____.

Answer 12

Increases; increases

Question 13

As kVp ____, a ____ range of photon energies is produced.

Answer 13

Increases; wider

Question 14

Contrast increases with all of the following EXCEPT:

a. Decreased kVp
b. Decreased field size
c. Decreased part thickness
d. Increased scatter

Answer 14

d. Increased scatter

Question 15

High contrast is directly related to:

Answer 15

The number of photoelectric interactions

Question 16

Which generator type results in the greatest decrease in contrast?

a. Single phase, 2 pulse
b. Three phase, 6 pulse
c. Three phase, 12 pulse
d. High frequency

Answer 16

d. High frequency

Question 17

Which of the choices does not increase contrast?

a. Increasing grid ratio
b. Increasing the amount of irradiated tissue
c. Decreasing filtration
d. Decreasing kVp

Answer 17

b. Increasing the amount of irradiated tissue

Question 18

The concept of contrast as it is displayed on a soft-copy monitor for digital images is described as:

Answer 18

Dynamic range

Question 19

As kVp increases, the percentage of Compton interactions ____ and contrast _____.

Answer 19

Increases; decreases

Question 20

When the tissue structure of the ankle joint is considered, the dramatic tissue differences between the muscles and bones of the ankle produce:

Answer 20

High subject contrast

Question 21

A fluoroscopic examination that uses barium as a contrast material would typically produce images with:

Answer 21

Short scale contrast

Question 22

The total amount of irradiated material is a function of:

Answer 22

Body part thickness and area of exposure

Question 23

Depending upon the kVp range, a visible change in contrast will not be seen unless kVp is minimally changed:

Answer 23

4-12%

Question 24

In order to reduce patient entrance skin exposure (ESE), higher kVp exposures are a consideration. It is important to remember that:

Answer 24

kVp values that are too high produce more scatter and reduce contrast

Question 25

After completing a radiograph using 27 mAs at 90 kVp, the image demonstrates adequate overall density but an area that is underpenetrated. In order to produce an optimum image in terms of contrast and penetration, the repeat image should be taken at:

Answer 25

27 mAs at 100 kVp (15% rule)

Question 26

kVp controls the proportional relationship of:

Answer 26

Compton and photoelectric interactions

Question 27

What should you expect to occur with a decrease in kVp?

Answer 27

More photoelectric interactions

Question 28

When digital imaging receptors are used,

a. kVp is not a consideration
b. Radiographic grids are not necessary
c. An exposure at 90 kVp would require a grid
d. Compton scatter is not a factor

Answer 28

c. An exposure at 90 kVp would require a grid

Question 29

All of the following factors would affect radiographic contrast EXCEPT:

a. Field size
b. SID and OID
c. Receptor characteristics
d. Focal spot size

Answer 29

d. Focal spot size

Question 30

An increase in x-ray beam filtration:

Answer 30

• Increases the number of Compton interactions
• Reduces contrast
• Increases the average photon energy

Question 31

When choosing between two radiographic grids, the k factor is different. Choosing a grid with the higher K factor will produce an image with:

Answer 31

High contrast

Question 32

With digital imaging systems, the primary factors affecting final image contrast are the:

Answer 32

Histogram and look-up-table (LUT)