Image Brightness/Contrast

Question 1

T/F: Radiography does not include understanding how to set a control panel.

Answer 1

False

Question 2

T/F: In radiography, optical density is a visible representation of the quantity of X-ray photons reaching the IR.

Answer 2

True

Question 3

T/F: Increasing mAs increases optical density.

Answer 3

True

Question 4

T/F: Increasing mAs increases brightness.

Answer 4

False

Question 5

Controls scale of contrast in the radiographic image

Answer 5

kVp

Question 6

Controls optical density in the radiographic image

Answer 6

mAs

Question 7

A radiograph that has sharp differences in optical density is called ___ contrast

Answer 7

high

Question 8

A radiograph with a small number of widely varying optical density values is said to possess ___ scale contrast

Answer 8

short

Question 9

has a short gray scale and used a low kVp

Answer 9

High scale of contrast

Question 10

has a long gray scale and used a high kVp

Answer 10

Low scale of contrast

Question 11

scale of contrast increases as kVp is ___

Answer 11

decreased

Question 12

scale of contrast decreases as kVp is ___

Answer 12

increased

Question 13

gray scale increases as kVp is ___

Answer 13

increased

Question 14

gray scale decreases as kVp is ____

Answer 14

decreased

Question 15

Doubling the mAs will result in:
1. increased patient dose
2. twice as many photons in the x-ray beam
3. increased radiographic density

Answer 15

1, 2 and 3

Question 16

If all other factors are unchanged and mA is decreased, image optical density will:

Answer 16

directly decrease

Question 17

If all other factors are unchanged and time is decreased, image optical density will:

Answer 17

directly decrease

Question 18

According to the reciprocity law, a technique of 200 mA, .5 second and 68 kVp can be changed to 400 mA, _______ second and 68 kVp.

Answer 18

0.25

Question 19

For the 1st exposure, 10 mA @ .5 seconds were used. There was considerable motion on the finished image. For the repeat, the time was decreased to .05 seconds. What mA would need to be used in order to maintain density?

Answer 19

100

Question 20

In the term kVp, the ‘p’ actually stands for:

Answer 20

highest voltage [peak]

Question 21

Long wavelength radiation will produce a radiograph with ___ scale contrast

Answer 21

short

Question 22

If an image (if the anatomical anatomy) is under-penetrated, the cause would be:

Answer 22

not enough kVp

Question 23

If an image (if the anatomical anatomy) is under-exposed, the cause would be

Answer 23

not enough mAs

Question 24

Which of the following would result in the shortest scale of contrast?

300 mA
1/30 sec
70 kVp

300 mA
1/60 sec
80 kVp

200 mA
1/20 sec
70 kVp

100 mA
2/10 sec
60 kVp

Answer 24

100 mA
2/10 sec
60 kVp

Question 25

T/F: Radiographic contrast and optical density of the manifest image in a digital image is primarily affected by predetermined algorithms in the computer.

Answer 25

True

Question 26

T/F: Differential absorption results in the process of image formation, whereby the x-ray beam interacts with the anatomic tissue and a portion of the beam strikes the image receptor.

Answer 26

True

Question 27

Limiting the size of the primary beam:

Answer 27

Beam restriction

Question 28

Refers to the radiation field size:

Answer 28

Exposure to the IR

Question 29

The range of colors of gray (the differences) in a radiograph including the dark areas and the bright (or clear areas)

Answer 29

Contrast scale

Question 30

A color of gray in the image

Answer 30

Density

Question 31

Differences in the brightness levels on the radiographic image is called:

Answer 31

Image contrast

Question 32

A longer scale of contrast (many shades of gray) within the part can be obtained by

Answer 32

increasing kVp

Question 33

An image with a brief range of widely different densities possesses 1. short scale contrast 2. long scale contrast 3. high contrast 4. low contrast

Answer 33

1 and 3

Question 34

In order to maintain the same density level and the mA is doubled, you should:

Answer 34

Half the time

Question 35

T/F: an additive disease requires an increase in kVp

Answer 35

True

Question 36

T/F: an additive disease requires a decrease in mAs

Answer 36

False

Question 37

Select the factors that affect subject contrast 1. physique 2. age 3. development (muscle vs. soft tissue) 4. pathology

Answer 37

1, 2, 3 and 4

Question 38

The thorax represents high subject contrast. Therefore, which of the following is most appropriate; high or low kVp?

Answer 38

high kVp

Question 39

Which of the following is not a primary factor in the production of a radiograph? -mA -seconds -intensification factor -kVp

Answer 39

intensification factor

Question 40

Which of the following does not belong in this group? -intensity -wavelength -penetration -kV

Answer 40

intensity

Question 41

The use of 15% kilovoltage rule in the maintenance of OD as mAs is halved offers the advantage of: -lower patient dose -shorter exposure times -all of the above

Answer 41

all of the above

Question 42

The 15% rule states:

Answer 42

That a change of 15% in kVp will result in approximately the the same change in density as doubling, or halving the mAs.

Question 43

At 30 inch SID, 200 mR of radiation reaches the IR changing the distance to 72 inches, the new intensity of radiation will be: To solve this problem, use the

Answer 43

Inverse square law

Question 44

An exposure is made at 40 inches using 100 mAs. At 60 inches, what is the new mAs to maintain density? To solve this problem, use the

Answer 44

Direct square law

Question 45

A technique of 160 mAs and 60 kV has been employed in producing a satisfactory image. In order to reduce patient exposure and to maintain density, _______ mAs and ______ kVp should be used. To solve this problem, use the:

Answer 45

15% rule

Question 46

"The intensity or exposure rate of radiation at a given distance from a point source is inversely proportional to the square of the distance" defines

Answer 46

Inverse square law

Question 47

Which affect the quality of a radiographic image? (1) Patient positioning (2) Selection of technique factors

Answer 47

1 and 2

Question 48

The amount of energy absorbed by an irradiated object is primarily controlled by: 1. Energy of incident photon 2. Atomic number of the tissue 3. Speed of the incident photon

Answer 48

1 and 2

Question 49

"...the ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly..."

Answer 49

contrast resolution

Question 50

The function of radiographic contrast in a radiograph is to:

Answer 50

Make detail visible

Question 51

The number of different shades of gray that can be stored and displayed by a computer system is termed:

Answer 51

Scale of contrast / grayscale

Question 52

For an analog image, the primary function of the mAs is to:

Answer 52

Regulate OD

Question 53

In an analog image, which of the following is primarily responsible for the scale of contrast on a radiograph?

Answer 53

kVp

Question 54

Which of the body tissues has the highest absorption when exposed to diagnostic x-rays?

Answer 54

Bone

Question 55

Which of the primary exposure factors has the greatest effect on beam quality, attenuation, and exposure latitude?

Answer 55

kV

Question 56

Which term might be used to describe an x-ray image that has a few shades of gray with marked visible differences between the ODs?

Answer 56

Short-scale contrast

Question 57

kVp is the controlling factor for which of the following? -quantity of x-rays -size of focal spot -OD -none of the above

Answer 57

None; kVp influences quantity but is not the controlling factor.

Question 58

The ability of an IR to display different definition shades of gray from light to dark.

Answer 58

Exposure latitude

Question 59

The range of exposure intensities an IR can accurately detect.

Answer 59

Dynamic range