Unit 2 Flashcards
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1
Q
List the prime factors that are selected by the technologist at the control panel
A
kVp
mA
s (time)
Distance is also a prime factor but not selected at the control panel
2
Q
List the 3 photographic properties that determine visibility of image details.
A
Density
Contrast
Noise
3
Q
Do mAs & kVp affect geometric properties?
A
No
4
Q
Define noise
A
Could be scatter, fog, artifacts or mottle. Basically, it’s anything that got in the way of a clearly visible image.
5
Q
Film density
A
The degree of image blackness or darkness due to the amount of black metallic silver on the film.
6
Q
What are the controlling and influencing factors for film density?
A
Controlling: mAs
Influencing: kVp & SID are primary - things like grids, collimation, anode heel effect, filtration, film screen speed, anatomic part, image processing, generator etc. are secondary factors.
7
Q
with CR and DR, what word is used instead of density?
A
Brightness
8
Q
Automatic rescaling
A
The processing that the computer does to adjust brightness on an image.
9
Q
Window level
A
Post-processing adjustment made at the computer workstation to adjust brightness.
10
Q
Wide window width is what kind of contrast?
A
Low contrast, long scale
11
Q
Narrow window width is what kind of contrast?
A
High contrast, short scale
12
Q
What are synonyms for subject contrast?
A
Differential absorption
Differential attenuation
Signal difference (Digital)
13
Q
What must you have in order to have radiographic contrast?
A
Subject contrast
14
Q
How can you tell if the radiograph was made using correct technique on a digital system?
A
By looking at the Sensitivity Number or Exposure Index
15
Q
Short scale is what window width and what contrast?
A
Narrow window width
High contrast
16
Q
Long scale is what window width and what contrast?
A
Wide window width
Low contrast
17
Q
Low contrast is what scale and what window width?
A
Long scale
Wide window width
18
Q
High contrast is what scale and what window width?
A
Short Scale
Narrow window width
19
Q
Contrast and density make details visible and sharp. True or false?
A
False. It only affects visibility, not sharpness.
20
Q
Adjusting the window level will affect:
A
Brightness
21
Q
Which of the following are related to high contrast? Short scale Long grey scale Wide window width Narrow window width High window level High density
A
Short scale
Narrow window width
22
Q
The controlling factor for both analog and digital imaging is mAs. True or false?
A
False. Only for analog
23
Q
Automatic rescaling means that all digital images should have correct brightness regardless of IR exposure. True or false?
A
True
24
Q
mA determines:
s determines:
mAs determines:
A
of electrons flowing per second
Exposure time in seconds
Total number of electrons striking the anode
25
Does mAs control density, contrast, both or none?
Only density
26
How much adjustment should be made to mAs for correcting image density?
By a factor of 2. (double or halve depending on if density needs to be increased or decreased)
27
What kind of relationship do mAs and film density have?
Direct proportional
28
A radiograph was taken using 70 kVp and 100 mAs. The film is severely overexposed & needs to be repeated. What factors should be used?
70 kVp
| 50 mAs
29
A radiograph was taken using 80 kVp and 20 mAs. It was severely underexposed and needs to be repeated. What factors should be used?
80 kVp
| 40 mAs
30
What change needs to take place to produce a visible film density change?
30%
31
A foot radiograph was taken using 60 kVp and 4mAs. The radiograph is slightly underexposed but needs to be repeated for positioning errors. What factors should be used?
60 kVp
| 5-6 mAs
32
A pelvis radiograph was taken using 75 kVp and 40 mAs. The radiograph is slightly underexposed and needs to be repeated because of an artifact. The radiographer used 75 kVp and 45 mAs for the repeat. The repeat is also underexposed, why?
mAs should have been changed to 52.
33
Should images be repeated for a high or low EI/S#?
No, only to correct poor quality. If an image must be repeated for quality, then adjustments can be made to mAs at that time.
34
Quantum mottle
AKA, quantum noise. Caused by an insufficient number of photons striking the IR.
35
Quantum mottle is an issue when using:
Insufficient mAs or kVp
High kVp, very low mAs
High speed film/screen systems
CR/DR systems
36
More signal does what to noise?
| Less signal does what to noise?
Less noise
| More noise
37
When kVp is increased what happens to the wavelength?
What happens to penetration?
What happens to subject contrast/signal difference?
Wavelength is shorter
Penetration is higher
Subject contrast is reduced
38
What is the controlling factor for radiographic contrast for film?
What does it also affect?
kVp
Density
39
With digital systems, kVp affects subject contrast. True or false?
True
40
kVp affects IR exposure but not brightness on digital systems. True or false?
True
41
Digital images must be repeated if exposure index or S# indicates an incorrect exposure. True or false?
False
42
mA & exposure time have an inverse proportional relationship with maintaining the same mAs. True or false?
True
43
Density, contrast and noise are photographic properties of the image and have no affect on sharpness or distortion. True or false?
True
44
as kVp increases, both beam penetrability and beam intensity increase. True or false?
True
45
If not enough mAs was used for an exposure, a film will lack density. True or false?
True
46
Can an incorrect kVp be corrected by adjusting mAs?
No
47
A 15% change in kVp has what affect on density?
Increases or decreases by a factor of 2.
48
What kVp range should the 10 kVp rule of thumb be used on?
60-80 kVp
49
Low kVp produces what scale of contrast? Why?
Short scale contrast due to decreased penetration/increased absorption and less scatter exiting tissue
50
Low kVp should be used with what type of tissue?
Tissue that has low subject contrast, low physical density or small thickness.
51
High kVp produces what scale of contrast? Why?
Long scale contrast due to increased penetration.
52
High kVp should be used with what type of tissue?
Tissue that has high subject contrast, high physical density or great thickness.
53
What kVp range is optimum for analog & digital for chest PA & Lat image?
Analog: 110-125
Digital: 110-125
54
What kVp range is optimum for analog & digital for AP abdominal image?
Analog: 70-80
Digital: 70-80
55
What kVp range is optimum for analog & digital for fingers/hand/wrist PA and toes image?
Analog: 50-55
Digital: 55-60
56
What kVp range is optimum for analog & digital for Fingers/Hand/Wrist lateral image?
Analog: 60-65
Digital: 65-70
57
What kVp range is optimum for analog & digital for foot/ankle? image?
Analog: 60 +/- 5
Digital: 60-70
58
To change contrast, which technical factor should be adjusted?
kVp
59
To change density, which technical factor should be adjusted?
mAs (especially for decreased density)
60
An AP Abdomen radiograph was taken using 95 kVp and 30 mAs. The film has excessive density and very long scale contrast. What should be done to improve image quality?
Lower the kVp
75-85 kVp is optimal for KUB
81 kVp and 30 mAs should be used
61
An AP Abdomen radiograph was taken using 95 kVp and 30 mAs. The film displays good density, however it has an overall grey appearance indicating too much kVp was used. What technique must be used to maintain density and improve the contrast?
81 kVp and 60 mAs
| decrease kVp by 15% and double mAs
62
An AP Abdomen radiograph was taken on an obese patient using 80 kVp and 500 mAs. Although penetration is adequate, the film is severely underdeveloped, lacking density and needs to be repeated. Maximum mAs for the generator is 500.
What can be done to correct density?
Will other image factors be affected?
90 kVp
| Contrast will decrease
63
Compare the controlling factor of density (or brightness) for film and digital images.
Film image density is controlled by technical factors (mAs & kVp) while digital is controlled by automatic rescaling.
64
List the prime factors that influence film density.
kVp and SID
65
How can a technologist determine if a film image is properly exposed?
The technologist looks at the density of the image.
66
How can a technologist determine if a digital image was properly exposed?
The technologist can look at the exposure index or sensitivity #.
67
What type of grey scale is associated with high contrast?
Short scale contrast (also narrow window width)
68
Describe the optical density of a film image that is severely underexposed.
The optical density will not be as great (dark) in a severely underexposed film.
69
How should the mAs be adjusted to correct a film image that is severely underexposed?
Doubling or quadrupling the mAs.
70
What is the minimum amount of change in mAs required to make a visible change in density?
A change of approximately 30% in mAs is required to make a visible change in density.
71
Compare the effect of mAs adjustments on image quality for digital and analog IR systems.
Because of the automatic rescaling, an adjustment in mAs has less impact on the digital image. A change by a factor of two makes a visual difference in film image quality.
72
Compare image quality of an overexposed film with an overexposed digital image.
An overexposed digital image would have been rescaled by the computer. The EI or S# would be outside the normal range, though. With film, the image would be too dark/optically dense.
73
Compare image quality of an underexposed film with an underexposed digital image.
The underexposed digital image would have been automatically rescaled but may show quantum mottle, however the EI or S# would be outside the acceptable range. With a film image, the image would be too bight or not show enough detail to be of diagnostic value.
74
What effect does an increase in mAs have on:
* Subject contrast:
* IR exposure:
* Film density:
* Radiographic contrast:
* Digital image brightness:
* Digital image contrast:
* Subject contrast: DOES NOT AFFECT
* IR exposure: INCREASES
* Film density: INCREASES
* Radiographic contrast: DOES NOT AFFECT
* Digital image brightness:DOES NOT AFFECT
* Digital image contrast: DOES NOT AFFECT
75
What effect does an increase in kVp have on:
* Subject contrast:
* IR exposure:
* Film density:
* Radiographic contrast:
* Digital image brightness:
* Digital image contrast:
* Subject contrast: DECREASES
* IR exposure: INCREASES
* Film density: INCREASES
* Radiographic contrast: DECREASES
* Digital image brightness: DOES NOT AFFECT
* Digital image contrast: DOES NOT AFFECT
76
What is the effect of increasing kVp by 15% on IR exposure? Why?
It doubles exposure, like doubling mAs would, because it increases the energy of the x-ray photons so more are transmitted. Also increases intensity.
77
What is the effect of increasing kVp by 15% on film density?
It would increase film density like doubling mAs would because it increases penetrability of the x-ray photos so more of them are transmitted. Also increases intensity.
78
What is the effect of increasing kVp by 15% on subject contrast?
It would decrease subject contrast (signal difference/differential attenuation)
79
What is the effect of increasing kVp by 15% on radiographic contrast? Why?
The increased energy would increase transmission through all the different subject contrasts which would decrease radiographic contrast/wide window width/long scale contrast.
80
What is the effect on optical density or image brightness from increasing kVp by 15% with a digital IR? Why?
It would have no effect because the computer uses automatic rescaling to adjust optical density.
81
A radiograph of the abdomen was taken at 95 kVp @ 20 mAs using a film/screen IR. The film displays good density; however it has an overall gray appearance indicating that too much kVp was used. What technique must be used to maintain density and improve the contrast?
81 kVp & 40 mAs
82
A radiograph is taken at 80 kVp and 60 mAs using a film/screen IR. The film is too dark and the density needs to be reduced by half.
Calculate two different combinations of technical factors that will decrease film density by one half. Compare the image qualities and patient radiation absorbed dose for each set.
70 kVp & 60 mAs or 80 kVp & 30 mAs
The 70 kVp & 60 mAs would give a higher patient radiation absorbed dose (RAD) not only because of the higher exposure that the mAs would produce.
Same image quality for each. Higher contrast on 70 kVp
83
A hip exam was taken using 70 kVp and 40 mAs using a film/screen IR. If it were to be repeated at 50kVp, what additional mAs will be required to reproduce the density of the original?
Trick question.
kVp of 50 is too low and would cause under-penetration. This cannot be fixed by more mAs.
84
Which of the following combinations of technical factors will produce the LEAST radiographic density?
65 kVp, 32 mAs, 40" SID
65 kVp, 32 mAs, 72" SID
75 kVp, 10 mAs, 40" SID
75 kVp, 10 mAs, 72" SID
75 kVp, 10 mAs, 72" SID
85
Which two images would have the greatest detail sharpness?
65 kVp, 32 mAs, 40" SID
65 kVp, 32 mAs, 72" SID
75 kVp, 10 mAs, 40" SID
75 kVp, 10 mAs, 72" SID
65 kVp, 32 mAs, 72" SID
| 75 kVp, 10 mAs, 72" SID
86
Which two images would have the least size distortion?
65 kVp, 32 mAs, 40" SID
65 kVp, 32 mAs, 72" SID
75 kVp, 10 mAs, 40" SID
75 kVp, 10 mAs, 72" SID
6f5 kVp, 32 mAs, 72" SID
| 75 kVp, 10 mAs, 72" SID
87
What would happen to IR exposure if the SID was decreased by a factor of 2 and no changes in technical factors were made?
IR exposure would increase, but by a factor of 4 (2^2).
88
What would happen to film density if the SID was decreased by a factor of 2 and no changes in technical factors were made?
Film density would increase by a factor of 4 (2^2).
89
What is the optimum range for kVp for a PA CXR?
110-125 kVp
90
What is the optimum range for kVp for a distal extremity?
50-65 kVp
91
What is the optimum range for kVp for an abdomen?
75-85 kVp
92
Digital images must be repeated if the EI or S# indicates incorrect exposure. True or False?
False
93
mA & exposure time have an inverse proportional relationship when maintaining the same mAs. True or False?
True
94
Density, contrast and noise are photographic properties of the image and have no effect on sharpness and distortion. True or False?
True
95
As kVp increases, both beam penetrability and beam intensity increase. True or False?
True
96
If not enough mAs was used for an exposure, a film will lack density. True or False?
True
97
Define signal
Transmitted x-ray photons
98
If kVp is increased what happens to penetration? What happens to subject contrast/signal difference?
Penetration is increased
| Subject contrast/signal difference is decreased
99
```
As mAs is increased, what happens to:
Subject contrast?
IR exposure?
Film densityy?
Radiographic contrast?
Digital brightness?
Digital image contrast?
```
Subject contrast? No change
IR exposure? Increases
Film density? Increases
Radiographic contrast? No change
Digital brightness? No change (rescaling)
Digital image contrast? No change (possible decrease in quantum mottle)
100
```
As kVp increases, what happens to:
Subject contrast?
IR exposure?
Film density?
Radiographic contrast?
Digital brightness?
Digital image contrast?
```
```
Subject contrast? Increases
IR exposure? Increases
Film density? Increases
Radiographic contrast? Decreases
Digital brightness? No change
Digital image contrast? No change
```
101
```
As SID increases, what happens to:
Subject contrast?
IR exposure?
Film density?
Radiographic contrast?
Digital brightness?
Digital image contrast?
```
Subject contrast? No change
IR exposure? Decreases (Inverse Square Law)
Film density? Decreases (Direct Square Law)
Radiographic contrast? No change
Digital brightness? No change (possible mottle)
Digital image contrast? No change
102
Film image is very light, lacking density, IR is severely underexposed. What are the technical adjustments?
Increase mAs at LEAST 2 times
OR
Increase kVp by 15%
103
Film image is very light, lacking density, with short scale contrast. Image is severely underexposed and underpenetrated. What is the best technical adjustment?
Increase kVp by 15%, additionally, may also be necessary to increase mAs by a factor of 2.
104
Film image is very dark, excessive density, IR is greatly overexposed. What is the best technical adjustment?
Decrease mAs by at least a factor of 2.
105
Film image is very dark, excessive density with very long scale contrast. Image is greatly overexposed AND underpenetrated. What is the best technical adjustment?
Decrease kVp by 15%. In addition, a decrease in mAs by a factor of 2 may be needed.
106
Film density is satisfactory but contrast scale is too long. What is the best adjustment?
Decrease kVp by 15% AND increase mAs by a factor of 2 to maintain correct density.
107
Film density is satisfactory but contrast scale is too short. What is the best adjustment?
Increase kVp by 15% AND decrease mAs by a factor of 2 to maintain correct density.
108
Film image is slightly light. It doesn't need to be repeated because of density, but because of positioning error. What adjustments can be made?
Increase mAs by 30%
OR
Increase kVp by 5%. This would also decrease contrast. Patient absorbed dose would be less with this adjustment compared to increasing mAs.
109
Film images is slightly dark. It doesn't need to be repeated because of density, but because of a positioning error. What adjustments can be made?
Decrease mAs by 30%
OR
Decrease kVp by 5%, adjusting mAs is best
110
Digital image is mottled. What technical adjustments could be made?
Increase mAs. The amount to increase is determined by EI or S#.
OR
Increase kVp by 15% to double IR exposure. If mAs is adequate, this should reduce mottle. If mAs is too low, this will not fix it.
111
Motion unsharpness; Film density is satisfactory and IR exposure is satisfactory. What are the adjustments that could be made?
Maintain mAs, but increase mA and decrease s
OR
Increase kVp by 15% and decrease s by decreasing mAs by a factor of 2 to maintain density.
112
If the beam intensity at 1 foot is 9mR, what is the intensity at 3 feet?
1mR
113
Beam intensity is 100 R at 80", what is the intensity at 40"?
400R
114
At 80" the exposure is 200 mR. What is the exposure at 160"?
50mR
115
The exposure at 100 cm is 100 mR. What is the exposure at 90 cm?
123.5 mR
116
If the exposure is 150 mR at 10 feet, at what distance is the exposure 1000 mR?
3.9 feet
117
A radiograph s produced using 30 mAs and 40" SID. If the SID is changed to 30", what mAs should be used to maintain film density or digital IR exposure?
16.9 mAs
118
A radiograph is obtained at 40" SID using 12.5 mAs. What mAs would maintain IR exposure or film density if the SID is changed to 60"?
28.1 mAs
119
A radiograph is obtained using 5 mAs at 100 cm. Film density or IR exposure is satisfactory. What mAs should be used if the SID changes to 200 cm?
20 mAs
120
A radiograph is produced using 22.5 mAs and 40" SID. What mAs would maintain IR exposure if the SID is changed to 80"?
90 mAs
121
A radiograph is produced using 60" SID and 60 mAs. What mAs would maintain IR exposure if the SID is changed to 45"?
33.8 mAs
122
```
As mAs is increased: (choose all that apply)
Film density is decreased
Film density is increased
Contrast is decreased
Contrast is increased
Detail sharpness is decreased
Detail sharpness is increased
Quantum mottle is decreased
Quantum mottle is increased
```
Film density is increased
| Quantum mottle is decreased
123
Increasing kVp will decrease subject contrast. True or False?
True
124
Decreasing kVp by 15% and doubling mAs will maintain film density and increase contrast. True or False?
True
125
A technologist can determine if a digital IR has been properly exposed by its density. True or False?
False
126
High contrast is also known as short scale contrast. True or False?
True
127
A digital image with wide window width has low contrast. True or False?
True
128
```
Which of the following technical factors will produce the shortest scale?
90 kVp and 8 mAs
80 kVp and 15 mAs
70 kVp and 30 mAs
60 kVp and 60 mAs
```
60 kVp and 60 mAs
129
What controls the brightness of digital images?
Automatic rescaling?
Signal difference?
Automatic rescaling and signal difference?
IR exposure?
Automatic rescaling
130
Which of the following will increase both patient and IR exposure?
Increasing mA while maintaining the same mAs
Increasing mAs
Increasing time while maintaining the same mAs
Increasing kVp
Increasing mAs
AND
Increasing kVp
131
```
Which of the following technical factors will produce the least contrast?
70 kVp and 30 mAs
80 kVp and 15 mAs
60 kVp and 60 mAs
90 kVp and 8 mAs
```
90 kVp and 8 mAs
132
```
What are the effects of scatter radiation on image quality? (choose all that apply)
Decreased film density
Increased film density
Decreased contrast
Increased contrast
Decreased detail sharpness
Increased detail sharpness
Decreased distortion
Increased distortion
```
Increased film density
| Decreased contrast
133
Low kVp should be used with body parts that have low subject contrast. True or False?
True
134
The contrast of a digital image can e adjusted after processing by changing the image window level. True or False?
False
135
```
As kVp is increased: (choose all that apply)
Film density is decreased
Film density is increased
Contrast is decreased
Contrast is increased
Detail sharpness is decreased
Detail sharpness is increased
Exit scatter is decreased
Exit scatter is increased
```
Film density is increased
Contrast is decreased
Exit scatter is increased
136
When SID increases with no change in technical factors, IR exposure:
Increases
Decreases
Does not change
Decreases
137
When SID is increased with no change in technical factors, film density:
Increases
Decreases
Does not change
Decreases
138
```
When SID is increased, to maintain lR exposure and film density:
mAs should be increased
mAs should be decreased
kVp should be increased
kVp should be decreased
There should be no change in mAs or kVp
```
mAs should be increased
139
What is the Inverse Square Law?
I1/I2= (SID2/SID1)^2
140
What is the Density Maintenance Formula?
mAs1/mAs2= (SID1/SID2)^2
141
With an increase in SID, what happens to detail sharpness?
It increases
142
With an increase in SID, what happens to size distortion?
It decreases
143
```
When SID decreases from 200 cm to 100 cm with no change in technical factors, IR exposure:
Increases by a factor of 2
Increases by a factor of 4
Decreases by a factor of 2
Decreases by a factor of 4
There is no change
```
Increases by a factor of 4
144
When SID decreases with no change in technical factors, film density:
Increases
Decreases
There is no change
Increases
145
```
When SID increases from 100 cm to 200 cm, to maintain IR exposure and film density:
Increase mAs by a factor of 2
Decrease mAs by a factor of 2
Increase mAs by a factor of 4
Decrease mAs by a factor of 4
Increase kVp by 15%
Decrease kVp by 15%
Don't change mAs or kVp
```
Increase mAs by a factor of 4
146
When SID increases, both image sharpness and magnification increase. True or False?
False (magnification decreases, sharpness increases).
147
```
Which of the technical factors will produce the least contrast?
60 kVp, 60 mAs
70 kVp, 30 mAs
80 kVp, 15 mAs
90 kVp, 8 mAs
```
90 kVp, 8 mAs
| look for highest kVp only, ignore mAs
148
```
Which of the technical factors will produce the shortest scale?
60 kVp, 60 mAs
70 kVp, 30 mAs
80 kVp, 15 mAs
90 kVp, 8 mAs
```
60 kVp, 60 mAs
| look for lowest kVp only, ignore mAs
149
Which will produce the greatest density?
70 kVp, 100 mA, 8/10s
70 kVp, 200 mA, 1/10s
70 kVp, 100 mA, 8/10s (80 mAs would produce the most density, kVp is the same in both)
150
Which will produce the least density?
70 kVp, 100 mA, 8/10s
80 kVp, 800 mA, 1/10s
70 kVp, 100 mA, 8/10s
| mAs is the same, 80 for both, so look for the lowest kVp
151
Which of the following will produce the most density?
70 kVp, 100 mAs
80 kVp, 80 mAs
```
80 kVp
(use 15% rule to make both kVps 80, then the mAs for the first one would be 50 to maintain density, which is lower than the 80 mAs)
```
152
```
Which will produce the greatest density?
60 kVp, 80 mAs
70 kVp, 20 mAs
80 kVp, 30 mAs
80 kVp, 20 mAs
```
80 kVp, 30 mAs
(Rule out 80 kVp/20 mAs because it's going to produce less density than the 80/30. Raise 70/20 to 80/20 and rule it out for less density. Raise 60/80 to 80 by raising 60 twice to 80/20 and rule it out for less density)
153
```
Which will produce the least density?
60 kVp, 80 mAs
70 kVp, 20 mAs
80 kVp, 30 mAs
80 kVp, 20 mAs
```
70 kVp, 20 mAs
(convert them all to 70 kVp, the first becomes 70/40, the second stays 70/20, the third becomes 70/60 and the fourth becomes 70/40)
