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Slockett's Rad Exposures > Ch 10 Radiographic Quality > Flashcards

Ch 10 Radiographic Quality Flashcards

(71 cards)

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1
Q

What is radiographic quality?

A

The exactness of representation of the anatomic part of interest in the finished radiograph

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2
Q

What are the (3) types of radiographic quality factors?

A
  1. Film factors (not allot of control over)
  2. Geometric factors (little bit of control over)
  3. Subject factors (no control over)
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3
Q

What quality factor do we have no control over?

A

Subject matter

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4
Q

What are the film factors?

A

Characteristic Curve

  • Speed
  • Latitude
  • Density
  • Contrast

Processing:

  • Time
  • Temperature
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5
Q

What are the Geometric Factors?

A
  • Distortion
  • Magnification
  • Blur
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6
Q

What are the Subject Factors?

A 
Contrast
Thickness
Density
Atomic #
Motion
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7
Q

Quality is the same for everyone? T/F

A

False

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8
Q

What is the criteria for evaluating quality?

A
  • Spatial resolution
  • Contrast resolution
  • Artifacts
  • Noise
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9
Q

What is spatial resolution?

A

Everything is in it’s appropriate place

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10
Q

What is contrast resolution?

A

Scales of gray

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11
Q

Spatial resolution is the ability to image objects that have ____ subject contrast.

A

High

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12
Q

Contrast resolution is the ability to detract or distinguish objects that have _____ subject contrast.

A

Similar

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13
Q

Which modality best demonstrates spatial resolution?

A

Diagnostic

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14
Q

What is noise?

A

The undesirable fluctuation of the OD of the image

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15
Q

Which modality best demonstrates contrast resolution?

A

CT, MRI

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16
Q

How do we get noise on an image?

A
  • Film graininess
  • Structure mottle- phosphor intensity screen
  • Quantum mottle-
  • Scatter Radiation-impact OD
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17
Q

What is Quantum Mottle?

A

Freckled appearance

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18
Q

What is the quality rule?

A

Fast image receptors have high noise and low spatial & contrast resolution

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19
Q

What is another name for the D max?

A

Shoulder

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20
Q

What is the Characteristic curve?

A

The graphic relationship between optical density and radiation exposure

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21
Q

What are the two pieces needed to contract a characteristic curve?

A

Sensitometer

Densitometer

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22
Q

What is the highest portion of the Characteristic curve?

A

Shoulder (D max)

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23
Q

What is the lowest portion of the Characteristic curve?

A

Toe

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24
Q

What is another name for the Characteristic curve?

A

H & D curve

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25
What is the most useful part of the characteristic curve?
Straight line portion
26
Is D max useful?
- No, it's black - Densest part - Burnt out
27
Is the Toe useful?
No, too white - Washed out - Loss of density
28
Where do you find your grays on the Characteristic curve?
In the straight line portion
29
What is the portion below the toe called?
Base + Fog (B+F)
30
What is B+F?
- What is inherent in the film and hasn't been exposed | - Anything outside the range of exposure
31
In B+F, what is Base?
What the manufacturer put in the film
32
In B+F, what is F?
Fog in the dark room
33
What is optical density?
Measurement of light incident on a processed film and the level of light transmitted through the film
34
What chemical produces the black?
Hydroqonone
35
What chemical produces the shades of gray?
Phenedone
36
Base + Fog= ?
Optical Density
37
Base + Fog should not exceed...
0.3
38
B + F (below toe) falls ______ the exposure range.
Outside
39
What is the OD range of the unexposed and processed radiographic films?
0.1- 0.3
40
Hydroqonone and phenedone work _______ to produce the blacks and grays.
Synergistically
41
Optical density is looking at what's _____ and what passes through
Inherent
42
B+F is the _______ and processed part of the processed radiographic film.
Unexposed
43
What is the base density?
0.1
44
What is the Fog density?
Doesn't exceed 0.2
45
What is the useful range of optical density?
0.25- 2.5 LRE
46
What are some reasons you might get an OD greater than 0.3?
- Aging of the film - Processor temp - Chemical fumes - Light - Radiation
47
What does LRE stand for?
Log Relative Exposure
48
What are the OD ranges dependent on?
- Viewbox illumination - Viewing conditions - Shape of characteristic curve
49
Optical density is measured ________.
Log rhythmically
50
What are the (2) types of Radiographic Contrast?
1. Image receptor contrast | 2. Subject contrast
51
What is Image Receptor Contrast?
Inherent in the film and influenced by processing | Things we cannot control
52
What is Subject Contrast?
That which attenuates through our patient and the kVp we performed the image with (other than kVp we cannot control)
53
How do we have any control over radiographic contrast, when it's determined by things we have no control over?
By adapting
54
For the same film type a change in _____ will affect contrast only when above or below the straight line portion.
Density
55
Contrast is defined by the slope of the ______ _____ portion.
Straight line
56
When density impacts _____ it is above or below the straight line portion
Contrast
57
Contrast that is defined by the slope of the straight line portion is also know as...
Average gradient
58
When changing technique at the D max...
Cut mAs in half
59
When changing technique at the toe you...
Double mAs
60
What is the Average Gradient?
The slope of the straight line drawn between two points on the characteristic curve at 0.25 and 2.0 above B+ F
61
What is the useful range of average gradient?
0.25- 2.0
62
The B+ F should not exceed...
0.3
63
What are the average gradient constants?
0. 25 | 2. 0
64
What is the B+ F range?
0.1- 0.3
65
When connecting (2) points on an H & D curve, the line is called the...
- Average Gradient - Straight line portion - Useful portion
66
What is the formula to determine Average Gradient?
AG= OD2 - OD1 _________ LRE 2 – LRE 1
67
The speed point on a film is defined as:
B + F+1
68
How do you chart a speed point?
As an open circle
69
When looking at a speed chart, the faster film is usually on the ____.
Left - It has a shorter scale of contrast - Goes from white to black faster
70
Speed point is ___ point above B + F.
1
71
What is speed?
How fast a film develops

Slockett's Rad Exposures (8 decks)

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