111- Chapter 16,17,18 Test Flashcards Preview

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Flashcards in 111- Chapter 16,17,18 Test Deck (96)
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1
Q

What can you do to exposure field size and tissue thickness to reduce scatter production

A

Decrease field size, compression band, PA

2
Q

Is pt thickness best reduced in the abdomen when the pt is supine or prone

A

Prone

3
Q

How is grid ratio determined

A

Height of lead strips / distance between strips

4
Q

For a given grid ratio, as height of strips increase, how does it effect scatter pickup

A

Increases

5
Q

For a given grid ratio, as distance between lead strips increases, how does it effect scatter pickup

A

Decreases

6
Q

Which type of grid is most challenging to use accurately

A

Cross hatched

7
Q

Define grid frequency

A

of lead strips per inch or cm

8
Q

Define grid selectivity

A

How much a grid allows the primary beam to transmit and how much scatter pickup

9
Q

Define K or contrast improvement factor

A

How well the grid cleaned up scatter and improved contrast

10
Q

What effect will imaging a thicker body part have on Compton and photoelectric interactions

A

Increase Compton decrease photoelectric

11
Q

What effect will imaging a thicker body part have on scatter production

A

Increase

12
Q

What effect will imaging a thicker body part have on image contrast

A

Decrease contrast

13
Q

When comparing a 5:1 grid and a 16:1, what prevents scatter the best

A

Neither

14
Q

When comparing a 5:1 grid and 16:1, which removes scatter the best

A

16:1

15
Q

When comparing a 5:1 grid and 16:1, which requires the biggest increase in technique

A

16:1

16
Q

When comparing a 5:1 grid and 16:1, which has the highest k factor

A

16:1

17
Q

When comparing a 5:1 grid and 16:1, which is more selective

A

16:1

18
Q

When comparing a 5:1 grid and 16:1, which requires more accurate positioning

A

16:1

19
Q

Describe the design of a focused grid in relationship to the Xray beam

A

Strips angle out to match divergence of beam

20
Q

What is the grid conversion factor formula

A

Mas 1 = GCF1

Mas2= GCF2

21
Q

What is the grid conversion factor for no grid

A

1

22
Q

What is the grid conversion factor for 5:1

A

2

23
Q

What is the grid conversion factor for 6:1

A

3

24
Q

What is the grid conversion factor for 8:1

A

4

25
Q

What is the grid conversion factor for 10:1

A

4.5

26
Q

What is the grid conversion factor for 12:1

A

5

27
Q

What is the grid conversion factor for 16:1

A

6

28
Q

What is grid cutoff and how can it occur

A

Undesired absorption of primary beam, off focus, level, center, upside down

29
Q

When should a grid be used

A

Body part greater than 9-10 cm. Kvp over 60

30
Q

How does air gap technique work in reducing scatter reaching IR and when might it come in handy

A

Greater OID drops off scatter, use when grid is unavailable

31
Q

How does an off level grid error occur when using a parallel grid

A

Short axis of grid is angled

32
Q

How does an off level grid error occur when using a focused grid

A

Short axis is angled

33
Q

How does an off center grid error occur when using a parallel grid

A

No error

34
Q

How does an off center grid error occur with a focused grid

A

Not centered on long axis

35
Q

How does an off focus grid error occur with a parallel grid

A

No error

36
Q

How does an off focus grid error occur when using a focused grid

A

When SID is out of focal range

37
Q

How does an upside down grid error occur when using a parallel grid

A

No error

38
Q

How does an upside down grid error occur when using a focused grid

A

Grid is upside down

39
Q

What causes the moiré grid error

A

When scanner frequency matches the grid frequency

40
Q

In the use of a focused grid, define grid radius

A

Distance from face of grid to convergence line

41
Q

In the use of a focused grid, define focal range

A

Range of SID that can be used with the grid

42
Q

What is the only type of grid error that occurs with both parallel and focused grids

A

Off level

43
Q

Which parts of a grid are radiopaque and radiolucent

A

Lead strips- radiopaque

Interspace- radiolucent

44
Q

What is the biggest variable a radiographer may face

A

Patient

45
Q

What factors may be increased in a patient with an additive pathological condition

A

Increase kvp by 5-15%

46
Q

Is an additive condition easier or more difficult for the beam to penetrate

A

More difficult

47
Q

What technical factors and how much are changed for destructive conditions

A

Decrease mas by 25-50%

48
Q

When comparing bone to fat, which one attenuates more of the beam

A

Bone

49
Q

When comparing bone to fat, which one has a higher atomic number

A

Bone

50
Q

When comparing bone to fat, which one has greater mass density

A

Bone

51
Q

When comparing bone to fat, which one provides greater radiographic contrast

A

Bone

52
Q

When comparing bone to fat, which one provides greater subject contrast

A

Bone

53
Q

How will increased OID affect subject detail

A

Decrease

54
Q

How will size of patient affect subject detail

A

Decrease

55
Q

How does a patients size and radiographic position affect size distortion in the form of magnification

A

Increase distortion

56
Q

Does Compton scatter contribute to diagnostic information of an image

A

No

57
Q

Does Compton scatter increase or decrease as tissue density increases

A

Decrease

58
Q

Does Compton scatter increase or decrease as patient thickness increases

A

Increase

59
Q

Does Compton scatter increase or decrease as volume of tissue increases

A

Increase

60
Q

Does Compton scatter increase or decrease as kvp increases

A

Increase

61
Q

Does Compton scatter increase or decrease radiographic contrast

A

Decrease

62
Q

Does Compton scatter increase or decrease density/IR exposure

A

Increase

63
Q

Does Compton scatter increase or decrease with an increase in atomic number

A

Decrease

64
Q

Does Compton scatter increase or decrease occupational dose

A

Increase

65
Q

What are the best ways to reduce the amount of scatter reaching the ir

A

Collimate, decrease kvp, use grid

66
Q

Transmitted radiation affects density/IR exposure how

A

Increases exposure

67
Q

How can the use of a compression band decrease tissue volume and subsequent scatter production

A

Push material down

68
Q

What is the main determining factor of how well a grid will be at improving contrast by removing scatter

A

Lead content

69
Q

Which direction do grid lines in the Bucky run in relation to the table and which way may the tube be angled

A

Long axis, cephalic or caudal

70
Q

When using a parallel grid there will always be some degree of grid cutoff. Where on the image will this be noticed

A

Lateral edges

71
Q

Is grid cutoff with a parallel grid more prevalent when using a long or short sid

A

Short

72
Q

With an off level grid error where on the image will cutoff be noticeable

A

Whole image

73
Q

With an off center grid error where on the image will the cutoff be noticeable

A

Whole image

74
Q

With an off focus grid error where on the image will the cutoff be noticeable

A

Edges

75
Q

With an upside down grid error where on the image will the cutoff be noticeable

A

Edges

76
Q

What is better for scatter cleanup: high or low frequency grid

A

Low frequency

77
Q

Subject density definition

A

Impact patient has on density/exposure

78
Q

Subject contrast definition

A

Degree of differential absorption in the body

79
Q

Subject detail definition

A

Dependent on structures position in the body in relationship to the Ir

80
Q

Subject distortion definition

A

Misrepresentation of size and shape of body part

81
Q

Additive or destructive: aerophagia

A

Destructive

82
Q

Additive or destructive: ascites

A

Additive

83
Q

Additive or destructive: atelectasis

A

Additive

84
Q

Additive or destructive: atrophy

A

Destructive

85
Q

Additive or destructive: bronchiectasis

A

Additive

86
Q

Additive or destructive: cirrhosis

A

Additive

87
Q

Additive or destructive: edema

A

Additive

88
Q

Additive or destructive: emphysema

A

Destructive

89
Q

Additive or destructive: empyema

A

Additive

90
Q

Additive or destructive: multiple myeloma

A

Destructive

91
Q

Additive or destructive: pneumonia

A

Additive

92
Q

Additive or destructive: osteoarthritis

A

Destructive

93
Q

Additive or destructive: osteochondroma

A

Additive

94
Q

Additive or destructive: osteomyelitis

A

Destructive

95
Q

Additive or destructive: sarcoma

A

Destructive

96
Q

Additive or destructive: sclerosis

A

Additive