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RADT A161 - Phys. 1 > Image Brightness/Contrast > Flashcards

Image Brightness/Contrast Flashcards

1
Q

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

A

False

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2
Q

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

A

True

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3
Q

T/F: Increasing mAs increases optical density.

A

True

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4
Q

T/F: Increasing mAs increases brightness.

A

False

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5
Q

Controls scale of contrast in the radiographic image

A

kVp

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6
Q

Controls optical density in the radiographic image

A

mAs

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7
Q

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

A

high

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8
Q

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

A

short

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9
Q

has a short gray scale and used a low kVp

A

High scale of contrast

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10
Q

has a long gray scale and used a high kVp

A

Low scale of contrast

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11
Q

scale of contrast increases as kVp is ___

A

decreased

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12
Q

scale of contrast decreases as kVp is ___

A

increased

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13
Q

gray scale increases as kVp is ___

A

increased

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14
Q

gray scale decreases as kVp is ____

A

decreased

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15
Q

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

A

1, 2 and 3

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16
Q

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

A

directly decrease

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17
Q

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

A

directly decrease

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18
Q

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.

A

0.25

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19
Q

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?

A

100

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20
Q

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

A

highest voltage [peak]

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21
Q

Long wavelength radiation will produce a radiograph with ___ scale contrast

A

short

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22
Q

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

A

not enough kVp

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23
Q

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

A

not enough mAs

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24
Q

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

A

100 mA
2/10 sec
60 kVp

25
Q

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

A

True

26
Q

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.

A

True

27
Q

Limiting the size of the primary beam:

A

Beam restriction

28
Q

Refers to the radiation field size:

A

Exposure to the IR

29
Q

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

A

Contrast scale

30
Q

A color of gray in the image

A

Density

31
Q

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

A

Image contrast

32
Q

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

A

increasing kVp

33
Q

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

A

1 and 3

34
Q

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

A

Half the time

35
Q

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

A

True

36
Q

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

A

False

37
Q

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

A

1, 2, 3 and 4

38
Q

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

A

high kVp

39
Q

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

A

intensification factor

40
Q

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

A

intensity

41
Q

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

A

all of the above

42
Q

The 15% rule states:

A

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

43
Q

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

A

Inverse square law

44
Q

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

A

Direct square law

45
Q

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:

A

15% rule

46
Q

“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

A

Inverse square law

47
Q

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

A

1 and 2

48
Q

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
A

1 and 2

49
Q

“…the ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly…”

A

contrast resolution

50
Q

The function of radiographic contrast in a radiograph is to:

A

Make detail visible

51
Q

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

A

Scale of contrast / grayscale

52
Q

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

A

Regulate OD

53
Q

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

A

kVp

54
Q

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

A

Bone

55
Q

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

A

kV

56
Q

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?

A

Short-scale contrast

57
Q

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

A

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

58
Q

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

A

Exposure latitude

59
Q

The range of exposure intensities an IR can accurately detect.

A

Dynamic range

RADT A161 - Phys. 1 (14 decks)

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