Radiographic Technique Flashcards Preview

Slockett's Rad Exposures > Radiographic Technique > Flashcards

Flashcards in Radiographic Technique Deck (101):
1

What controls quantity?

mAs

2

What influences and determines the quantity and quality of x-rays ?

Exposure Factors

3

Radiation quality refers to x-ray beam penetrability, best measured by what?

HVL (Half Value Life)

4

What are the (4) prime exposure factors?

1. kVp
2. mA
3. Exposure time
4. SID

5

High kVp _____ image contrast.

Reduces

6

What controls how fast the electrons are sent across the tube?

Kilovolts

7

What controls beam quality?

kVp

8

What controls beam penetrability?

kVp

9

What controls the radiographic scale of contrast?

kVp

10

What determines the # of photons, radiation quantity, OD and patient dose?

mA

11

What affects the number of x-rays produced?

mA

12

What are the available mA stations?

50, 100, 200, 300, 400 & 600

13

Does changing the mA change the kinetic energy of e-?

No

14

What relationship does mA quantity and patient dose have?

They are directly proportional

15

Short exposure time _____ image blur

Reduces

16

What must you do when using short exposure times to maintain x-ray intensity?

Increase mA

17

Single phase can not produce an image under...

8ms

18

Three phase can produce an image under...

1ms

19

mAs=

(mA)x (s)

20

What does mAs control?

-Radiation quantity
-Changes the number of electrons
-Optical density
-Patient dose

21

Does mAs change the energy of x-rays produced?

No, just the number

22

mAs is a key factor in the control of ________ ________.

Optical Density

23

What is the reciprocity law?

OD will be constant for any combination of mA and exposure time that results in constant mAs

24

Does distance have much affect on quality?

No

25

Does distance have an affect on density?

Yes

26

Does distance affect x-ray intensity?

Yes

27

What does the square law do?

Determines the required change in mAs after a change in SID to maintain OD

28

What are some patient factors when determining technique?

-Body habitus
-Thickness of part
-Body composition
-Pathology

29

What are the (4) types of body habitus?

1. Hypersthenic
2. Sthenic
3. Hyposthenic
4. Asthenic

30

Define:
Hypersthenic

-Short & wide
-Chest and abdomen are broad
-5%
-Lungs are short and wide
-Stomach is high and transverse

31

Define:
Sthenic

-Average body type
-50% of population
-Active or strong
-Slender version of Hypersthenic

32

Define:
Asthenic

-Opposite of Hypersthenic
-10% of population
-Frail, poor muscle tone
-Narrow, long, shallow
-Diaphragm is low
-Abdominal cavity rests in pelvic region

33

Define:
Hyposthenic

-35%
-High splenic flexure
-Stomach is J shaped and extends into iliac crest region

34

In general, what kind of technique does a soft tissue neck require?

Low kVp & high mAs

35

In general, what kind of technique do extremities require?

Low kVp

36

In general, what kind of technique does a chest require?

High kVp

37

In general, what kind of technique does an abdomen require?

Middle kVp

38

What are the (4) image quality factors?

Key word DICO
1. Disorientation
2. Image Detail
3. Contrast
4. Optical Density

39

What is OD?

The degree of blackening of the finished radiograph

40

When OD is high=

-Too dark
-Overexposed

41

When OD is low=

-Too light
-Underexposed

42

OD can be controlled by mAs and SID? T/F

True

43

Quantity=

mAs

44

Quality=

HVL

45

What is more efficient, a single phase or a three phase?

3 phase

46

When SID is shortened, what happens to your mAs?

It goes down

47

When SID is increased, what happens to your mAs?

It goes up

48

What are the (4) types of generators?

1. Half wave rectification
2. Full wave rectification
3. 3 phase power
4. High frequency generator

49

Half Wave:

-Only produces x-rays half the time
-Drops to zero every time
-x-rays are not produced on negative side
-Rarely used

50

Full Wave:

-Consistant, but drops to zero

51

3 phase power:

-6 & 12 pulse
-Nearly constant output & exposure
-energy is higher
-Higher quantity & quality

52

High frequency:

-Less than 1% ripple
-Constant output
-Great efficiency

53

What are the effects of a destructive disease?

-Destroying part of tissue, bone, ligaments
-Taking away, making more lucent

54

What are the effects of a constructive disease?

-Growing
-Dense

55

How much of in increase is required for a visible change in OD?

30%

56

When mAs is doubled, you get...

Double the density

57

When only mAs is changed it is either ____ or ____.

Halved or doubled

58

When mAs is doubled=

Your density is doubled

59

When kVp is changed it must be increased by __% to produce a visible change in OD.

4%

60

The 15% rule is the same as?

Doubling the mAs

61

To maintain OD a 15% increase in kVp would require a reduction of ____ the mAs.

Half

62

Does the 15% rule apply to kVp or mAs?

kVp

63

A strip that goes from black to white quickly would have a...

-Short scale
-High contrast
-Lower kVp
-Black and white

64

A strip that goes from black to white slowly would have a...

-Long scale
-Low contrast
-High kVp
-Many shades of gray

65

What is contrast?

Differences between things that are adjacent to one another

66

Contrast is controlled by...

kVp

67

A result of the differences in attenuation of the x-ray beam as it penetrates various structures.

Contrast

68

The variation in OD between adjacent anatomic structures.

Contrast

69

A chest would have what scale of contrast?

Long scale of contrast

70

Short scale contrast gives you ___ contrast radiographs.

High

71

High contrast radiographs would have...

-Short scale contrast
-Fewer shades from white to dark

72

Bone work would have short scale ____ contrast

High

73

Long scale contrast produces _____ shades of gray.

Many

74

How much kVp is requited to see a difference in contrast?

4 kVp

75

At low kVp, how much change is needed to see a difference?

2 kVp

76

At high kVp, how much kVp is needed to see a difference?

10 kVp

77

High kVp will give you ___ contrast.

Low

78

A chest has ___ subject contrast.

High

79

High subject contrast has ____ variations in tissue composition

Greater

80

A hand has ____ subject contrast.

Low

81

An abdomen has ____ subject contrast.

Low

82

What is the 5% rule?

An increase in kVp by 5% requires a reduction in 30% mAs

83

What is image detail?

Sharpness of small structures or spatial resolution of the image

84

How is image detail evaluated?

Sharpness of image detail
Visibility of image detail

85

What is sharpness?

Clarity or blur of the structural lines

86

What is visibility?

Seeing that there is anatomy

87

Sharpness is controlled by...

-Focal spot size (FSS)
-SID
-OID
-Intensifying screen

88

What can reduce visibility?

Fog

89

What is distortion?

Misrepresentation of an object and shape due to position of the tube or anatomic part

90

What are disadvantages of distortion?

-Elongation
-Foreshortening

91

What is an advantage of distortion?

Allows for better visualization of anatomy

92

Variable kVp chart:

-kVp varies according to thickness of anatomic part
-Provides radiographs with shorter scales of contrast
-Other factors stay the same

93

Fixed kVp chart:

-kVp stays constant
-mAs varies
-Developed by Arthur Fuchs
-Provides longer scales of contrast

94

High kVp chart:

-Used for barium exams, contrast exams, CXR
-Ensures adequate penetration
-Decrease in mAs
-Reduces patient dose

95

AEC:

-Use of computer assisted automatic/ electric timers and photocells
-Patient positioning must be accurate
-Terminated when the image receptor has received the appropriate radiation exposure
-Most have 2s override

96

An increase of 15% in kVp is equivalent to...

Doubling the mAs in terms of density

97

Long scale contrast:

-Low contrast
-Many shades of gray
-Higher kVp

98

Short scale contrast:

-High contrast
-Black and white
-Lower kVp

99

What controls contrast?

kVp

100

What controls density?

mAs

101

A high grid ratio will produce a short scale contrast? T/F

True