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

Ch 10 Radiographic Quality Flashcards

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
Q

What is the most useful part of the characteristic curve?

A

Straight line portion

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26
Q

Is D max useful?

A
  • No, it’s black
  • Densest part
  • Burnt out
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27
Q

Is the Toe useful?

A

No, too white

  • Washed out
  • Loss of density
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28
Q

Where do you find your grays on the Characteristic curve?

A

In the straight line portion

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29
Q

What is the portion below the toe called?

A

Base + Fog (B+F)

30
Q

What is B+F?

A
  • What is inherent in the film and hasn’t been exposed

- Anything outside the range of exposure

31
Q

In B+F, what is Base?

A

What the manufacturer put in the film

32
Q

In B+F, what is F?

A

Fog in the dark room

33
Q

What is optical density?

A

Measurement of light incident on a processed film and the level of light transmitted through the film

34
Q

What chemical produces the black?

A

Hydroqonone

35
Q

What chemical produces the shades of gray?

A

Phenedone

36
Q

Base + Fog= ?

A

Optical Density

37
Q

Base + Fog should not exceed…

A

0.3

38
Q

B + F (below toe) falls ______ the exposure range.

A

Outside

39
Q

What is the OD range of the unexposed and processed radiographic films?

A

0.1- 0.3

40
Q

Hydroqonone and phenedone work _______ to produce the blacks and grays.

A

Synergistically

41
Q

Optical density is looking at what’s _____ and what passes through

A

Inherent

42
Q

B+F is the _______ and processed part of the processed radiographic film.

A

Unexposed

43
Q

What is the base density?

A

0.1

44
Q

What is the Fog density?

A

Doesn’t exceed 0.2

45
Q

What is the useful range of optical density?

A

0.25- 2.5 LRE

46
Q

What are some reasons you might get an OD greater than 0.3?

A
  • Aging of the film
  • Processor temp
  • Chemical fumes
  • Light
  • Radiation
47
Q

What does LRE stand for?

A

Log Relative Exposure

48
Q

What are the OD ranges dependent on?

A
  • Viewbox illumination
  • Viewing conditions
  • Shape of characteristic curve
49
Q

Optical density is measured ________.

A

Log rhythmically

50
Q

What are the (2) types of Radiographic Contrast?

A
  1. Image receptor contrast

2. Subject contrast

51
Q

What is Image Receptor Contrast?

A

Inherent in the film and influenced by processing

Things we cannot control

52
Q

What is Subject Contrast?

A

That which attenuates through our patient and the kVp we performed the image with
(other than kVp we cannot control)

53
Q

How do we have any control over radiographic contrast, when it’s determined by things we have no control over?

A

By adapting

54
Q

For the same film type a change in _____ will affect contrast only when above or below the straight line portion.

A

Density

55
Q

Contrast is defined by the slope of the ______ _____ portion.

A

Straight line

56
Q

When density impacts _____ it is above or below the straight line portion

A

Contrast

57
Q

Contrast that is defined by the slope of the straight line portion is also know as…

A

Average gradient

58
Q

When changing technique at the D max…

A

Cut mAs in half

59
Q

When changing technique at the toe you…

A

Double mAs

60
Q

What is the Average Gradient?

A

The slope of the straight line drawn between two points on the characteristic curve at 0.25 and 2.0 above B+ F

61
Q

What is the useful range of average gradient?

A

0.25- 2.0

62
Q

The B+ F should not exceed…

A

0.3

63
Q

What are the average gradient constants?

A
  1. 25

2. 0

64
Q

What is the B+ F range?

A

0.1- 0.3

65
Q

When connecting (2) points on an H & D curve, the line is called the…

A
  • Average Gradient
  • Straight line portion
  • Useful portion
66
Q

What is the formula to determine Average Gradient?

A

AG= OD2 - OD1
_________
LRE 2 – LRE 1

67
Q

The speed point on a film is defined as:

A

B + F+1

68
Q

How do you chart a speed point?

A

As an open circle

69
Q

When looking at a speed chart, the faster film is usually on the ____.

A

Left

  • It has a shorter scale of contrast
  • Goes from white to black faster
70
Q

Speed point is ___ point above B + F.

A

1

71
Q

What is speed?

A

How fast a film develops

Slockett's Rad Exposures (8 decks)

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