Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

RAD 121 > Test 3 > Flashcards

Test 3 Flashcards

0
Q

How and why do technique systems provide consistent image quality

A

By reducing variability so you can reduce repeats and avoid excessive or dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What is the primary goal of technique systems

A

To provide consistent image quality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the advantages of a Fixed kV

A 
Decrease or dose
Provide more information on image
Consistent image contrast and density
Wide exposure latitude
Reduce tube wear
Decreased time settings=less motion
Easy to remember
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Disadvantages of a fixed Kv

A

More scatter
Lower contrast
Less visibility (grayer image)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Advantages to a variable Kv

A

Permit small incremental changes with changing body part thickness
Higher image contrast
Enhanced visibility of fine detail
Increased perception of resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Disadvantages of a variable Kv

A 
Increased or dose
Less info on image
Inconsistent image contrast and density
Narrow exposure latitude
Increased tube wear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are computerized exposure control systems

A

It utilizes vast databank of technique systems
Inherent part of control console
Tech chooses exam and computerized factors appear
Factors may be modified to meet non routine conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

7 steps to building a technique chart

A
  1. Produce phantom images - measure part ️size
  2. Select optimal phantom image - selected by radiologist
  3. Extrapolate technique chart - use 15% rule and adjust for part thickness
  4. Phantom testing
  5. Clinical trials
  6. Clinical fine tuning
  7. Ongoing fine tuning o
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is AEC

A

It is sensors in the Bucky that stops exposure when image reaches appropriate density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Advantages of AEC

A

Fewer repeats
Decreased pt exposure
Increased efficiency of dept

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Limitations of AEC

A

Requires skill techs - positioning and knowledge of AEC devices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does tech control time with AEC

A

Higher MA = shorter time

Lower MA = longer time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What tech factors does tech set when using AEC

A

MA KV AND SID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are two types of AEC devices

A

Phototimers

Ionization chambers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Characteristics of Phototimers

A

Located behind the IR
“Old fashioned”
Photomultiplier tube and fluoroscopic screen
Terminates when appropriate amount of LIGHT from screen reaches the photomultiplier tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Characteristics of ionization chamber

A

Located between pt and IR
“Modern”
Gas filled ionization chamber
Terminates exposure when proper amount of RADIATION is detected by ionization o air in chamber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is another name for the two AEC devices

A

Phototimers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why are the two most important decisions when using AEC

A

Patient positioning
Detector/chamber/cell selection
* detector must sample radiation coming directly from area of interest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Without proper ________ of _________ AEC may actually increase repeats and or dose

A

Knowledge of positioning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are 5 causes of improper image density when using AEC

A
  1. Inaccurate positioning(#1 cause)
  2. Poor collimation
  3. Wrong “speed” IR (film/screen)
  4. Equipment failure
  5. Pt conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is minimum response time (MRT)

A

Lag time between AEC recognizing enough radiation, sending signal to terminate exposure , and switch thrown to end exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the equipment limitation for MRT in older and newer equipment

A 
Older = 30 millisec
Newer = 1 millisec
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the upper limit set by the safety device on AEC

A

600 mAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What would cause the back up tune to activate

A 
Excessively large pt
Wrong detector selected
Wrong tube selected
Incorrect tube/Bucky alignment
Incorrect back up timer setting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

T/F in order to produce the correct density the radiation reaching the AEC chamber must come from the part of interest

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

T/F increased scatter will produce an overexposed image when using AEC

A

False (underexposed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Will a photocell covered by heavy absorber produce an overexposed, underexposed, or no change image

A

Over exposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

When the primary beam strikes the photocell will that produce an overexposed underexposed or no change image

A

Underexposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

When you want to image bone but the photocell is covered by soft tissue …. Overexposed underexposed or no change

A

Underexposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Using table Bucky but selected wall Bucky…… Overexposed underexposed or no change

A

Overexposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Imaging an AP lumbar spine but have selected outer chambers…… Overexposed underexposed or no change

A

Underexposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Poor collimation when imaging an obese pt and using a high Kv…. Overexposed underexposed or no change

A

Underexposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is photographic properties

A

The visibility of recorded detail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is geometric properties

A

The sharpness I recorded detail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Why is radiographic density

A

The amount of overall blackness produced on the processes image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is radiographic contrast

A

Is the degree o difference or ratio between adjacent densities

Scale of contrast
Long scale=low contrast
Short scale=high contrast

36
Q

What does radiographic density determine

A

The completeness o the image recorded upon the radiographic film.
It is the overall blackening of the film caused by the intensity of radiation

37
Q

What are the 2 controlling factors that affect density

A

Milliamperage and time

38
Q

What 9 things influence density

A 
kvp 
SID
Grid
Film screen speed
Collimation
Anatomic part (thickness of part)
Anode heel effect
Tube filtration
Film processing
39
Q

MA and exposure time control the _______ of radiation reaching the image receptor

A

Quantity

40
Q

MAs and density have what kind of relationship

A

Proportional (direct)

Double mAs double density

41
Q

To make a visible change in density the minimum amount of change in mAs is approximately ________

A

30%

42
Q

How does kvp influence density?

A

It alters the energy and amount of penetrating ability of the xray beam

43
Q

Electron speed is determined by_______

A

The voltage

44
Q

As the voltage increases

A

The electrons travel faster
The greater the energy of the X-rays produced
The greater the penetrating ability of the X-rays

45
Q

Changing the Kv by 15% will have the same effect on density as

A

Doubling or doing the mAs by half

46
Q

Using the 15% rule

A

To increase density - add 15% to kvp
To decrease density - subtract 15% from kvp
To maintain density - when increasing Kv by 15% divide mAs by 2 when decreasing Kv 15% multiply mAs by 2

47
Q

When would you change kvp to change density

A

When change is contrast Is also desired

48
Q

SIDS effect on density

A

Inverse square law - doubling SID decreases density to 1/4

49
Q

The inverse square law states that the intensity o the xray bean is ________ _________ to the square of the distance from the source

A

Inversely proportionate

50
Q

As SID increases density _______

As SID decreases density _______

A

Decreases

Increases

51
Q

When SID is increased what must be done to maintain density

A

Increase mAs

52
Q

Exposure maintenance formula (SID and density)

A

MAs 1 = SID1^2
-–—— ———
MAs 2 SID 2^2

53
Q

If adding a grid the mAs must be ________

A

Increased

54
Q

Formula for grid and mAs

A

Mas1 = GCF1
——- ——-
Mas2 GCF2

55
Q

Grid conversation factors

A

No grid ➡️ 1x

5: 1➡️2x
6: 1➡️3x
8: 1➡️4c
12: 1➡️5x
16: 1➡️6x

56
Q

A radiograph was taken without a grid using 3.2 mAs. If an 8:1 grid is used what would the new mAs be?

A
  1. 2 mAs ; 8:1 grid : GCF 4

3. 2 x 4 = 12.8

57
Q

The greater the speed of the film screen the ________ the amount of density produced on radiograph

A

Greater

58
Q

Increasing the film screen speed requires a _______ to be made to the mAs

A

Decrease

59
Q

Film screen systems are classified by their

A

Relative speed factor (RS)

60
Q

Formula for film screen and mAs

A

MAs 1 = RS 2
——– ——–
MAs 2. RS1

61
Q

A thick body part absorbs more radiation which will reflect (more or less) density

A

Less

62
Q

A thin body part transmits more radiation which will reflect (more or less) density

A

More

63
Q

To maintain density when imaging a thicker body part the mAs needs to be

A

Increased

64
Q

For every change in part ️thickness of 4 cm the mAs must be adjusted by a factor of

A

2x

65
Q

When using a fixed mAs and variable kvp each cm increase in pt ️thickness requires a(n)

A

Increase in 2 kvp

66
Q

There is a decrease in the primary xray beam intensity in the (cathode or anode) side of the tube

A

Abide

67
Q

Place the thickest part under the (cathode or anode) end will help decrease visibility of the anode heel effect

A

Cathode

68
Q

Density is one of two ________ properties that comprise visibility of detail

A

Photographic

69
Q

What is the range of densities visible to the human eye

A

Photographic optical .25-2.5

70
Q

Which is worse to be too dark or too light in density

A

Too light

71
Q

The controlling factor for density is the

A

MAs

72
Q

The text indicates there are ______ potential factors affecting density with _____ being negligible

A

13

2

73
Q

T/F a dark radiograph has recorded too much information

A

True

74
Q

Whenever s choice must be made between excess and insufficient density the wise decision is always the choice of the lighter image

A

False

75
Q

T/f an AEC system controls time not milliamperage

A

True

76
Q

T/f the configuration of the generator is another important consideration in how kvp affects density

A

True

77
Q

When in doubt it is advisable to adjust density by a step at a time

A

False

78
Q

T/f as SID Increases density decreases

A

True

79
Q

T/f as OID increases density increases

A

False

80
Q

t/f as filtration increases density decreases

A

True

81
Q

T/f Restricting the primary beam increases density

A

False

82
Q

The density of the radiographic image is the

A

Easiest prime technical factor to evaluate
Result o black metallic silver deposited on the radiograph
Degree of overall blackness

83
Q

The _______ factors should be used as the principal method for adjusting radiographic density

A

Controlling

84
Q

Which generator produces the least amount of radiographic density

A

Single phase, 2 pulse

85
Q

Which generator produces the greatest amount of radiographic density

A

A high frequency generator

86
Q

Which factor influences the average energy of photons reaching the radiograph film

A

Kvp

87
Q

The 15% rule changes

A

Density and contrast

88
Q

The relationship between exposure and SID is

A

Inversely proportional

RAD 121 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions