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Physics 2 > Ch 26-29: Photographic & Geometric Properties > Flashcards

Ch 26-29: Photographic & Geometric Properties Flashcards

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1
Q

Window Level =

A

Brightness

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2
Q

Window Width =

A

Contrast

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3
Q

Where does contrast from?

A

Post processing - window width
Preprocessing - LUTs

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4
Q

DI =

A

Deviation Index - color coded

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5
Q

EI =

A

Exposure Index - a value

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6
Q

What are the two photographic properties of radiography

A

IR Exposure & Contrast

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7
Q

Where does visibility of detail come from

A

Sufficient IR exposure & contrast allow anatomical details to be seen

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8
Q

Where does IR exposure come from

A

Mas + contrast

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9
Q

If an image is overexposed, what can you do

A

You can use window level to brighten the image

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10
Q

If an image is underexposed, what can you do

A

You must repeat to correct

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11
Q

How are mas & IR exposure related (inversely or directly)

A

Directly

If you increase your MAs, you increase IR exposure

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12
Q

In order to see a visible difference between two images, how much must you increase your mas factor

A

25% - 35%

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13
Q

What is the rule of thumb for increasing or decreasing MAs

A

You half it or double it. If it doesn’t need either of those, it doesn’t truly need to be repeated

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14
Q

What is rule of thumb for increasing or decreasing KVP

A

15% rule.

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15
Q

If you increase kvp by 15% without a compensation in MAs, what are you doing to your overall exposure

A

Doubling it

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16
Q

If you decrease your kvp by 15% without a compensation in MAs, what are you doing to your overall exposure

A

Halfing it

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17
Q

When you increase KVP, what are you creating more of

A

Scatter - Compton

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18
Q

Is KVP & IR exposure directly or indirectly related

A

Directly

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19
Q

How much ripple does a single phase generator create

A

100%

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20
Q

How much ripple does 3 phase generators make

A

4% - 14%

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21
Q

How much ripple does a high frequency generator make

A

Less than 1%

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22
Q

The higher the frequency of generator used, the more photon energy is made. What does this do to IR Exposure

A

Increases it.

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23
Q

What does Focal Spot Size effect

A

Spatial Resolution/Detail

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24
Q

What does anode heel effect do to Ir Exposure

A

You end up with a higher exposure on the cathode side.

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25
Q

How do you combat anode heel effect when it comes to IR Exposure

A

Collimate

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26
Q

How is SID & IR exposure related - indirectly or directly

A

Indirectly

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27
Q

If you increase SID, what does it do to Exposure

A

Decreases

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28
Q

What do you do to maintain good IR exposure when increasing SID

A

Increase Mas to compensate- exposure maintenance formula

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29
Q

How are OID & IR exposure related - directly or indirectly

A

Indirectly

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30
Q

If you increase OID what does it do to your IR exposure

A

Decreases it

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31
Q

How are filtration and IR exposure related - directly or indirectly

A

Indirectly

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32
Q

The more filtration used = the _____ IR Exposure

A

Less - filters out soft photons

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33
Q

How does air effect exposure

A

^ air = ^ exposure

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34
Q

How does a grid effect ir exposure

A

^ grid = less exposure

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35
Q

What kind of latitude does digital imaging have

A

A wide latitude and dynamic range

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36
Q

What is the primary controller of subject contrast

A

Kvp

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37
Q

What does increased field size do to subject contrast

A

Decreases - a bigger field size causes more scatter

38
Q

What does a higher part density do to subject contrast

A

Increases - more absorption into one part

39
Q

Can subject contrast be improved by post processing

A

No

40
Q

Does kvp have any effect on image contrast

A

No

41
Q

What does contrast come from

A

LUT

42
Q

Does MAs effect contrast

A

Yes

43
Q

How does mas effect contrast

A

More mas - more contrast

44
Q

how does anode heel effect contrast

A

There’s more contrast on the cathode end - need to collimate - very little effect

45
Q

How does SID effect contrast

A

Increased SID = less contrast

46
Q

How does OID effect contrast

A

Increased OID = decreases contrast UNLESS using air gap technique

47
Q

How does filtration effect contrast

A

Decreases contrast

48
Q

How does increased collimation effect contrast

A

Increases contrast - reduces scatter

49
Q

How does an increased part size effect contrast

A

Decreases contrast - increases scatter

50
Q

How does a grid effect contrast

A

Increases - grids clean up scatter

51
Q

What are the two types of geometric properties

A

Spatial resolution
Distortion

52
Q

What are the names for spatial resolution

A

Detail
recorded detail
Sharpness
Definition

53
Q

How is spatial resolution measured in

A

Line pairs per millimeter
Lp/mm

54
Q

T or F: good detail exists even when it cannot be seen due to poor visibility

A
55
Q

What do geometric properties do

A

Control detail

56
Q

What do photographic properties do

A

Control visibility of detail

57
Q

Grayscale bit depth range

A

8-32 bytes

58
Q

High frequency spatial resolution

A

Short wavelength
High contrast
High resolution
Low kvp
Line pairs closer

59
Q

Low frequency spatial resolution

A

Longer wavelength
Low contrast
Low resolution
High kvp
Line pairs further apart

60
Q

Quality Control Testing tools

A

Spread Function
Spatial Frequency

61
Q

Tiny hole drilled into sheet of lead QC

A

Point Spread

62
Q

Slit made into lead QC

A

Line Spread

63
Q

Sharp edge of lead QC

A

Edge Spread

64
Q

Tool that shows varying line pairs together to visualize smallest pairs QC

A

Spatial Frequency

65
Q

Used to measure the accuracy of an image to original object 0-1 scale

A

Modular Transfer Function (MTF)

66
Q

Do we do MTF testing

A

No - it’s in the system

67
Q

Noise - where does it come from

A

Ambient
System
Quantum

68
Q

Want what for SNR

A

High signal low noise

69
Q

What is CNR

A

Contrast to Noise Ratio - depends on contrast & SNR

70
Q

A processing algorithm that averages incoming analog data - measures distance between dels & is sampled twice each cycle

A

Nyquist Criterion- in the system

71
Q

Occurs when Nyquist Criterion is violated

A

Aliasing - misrepresentation of data

72
Q

What are the 3 critical distances we deal with

A

SOD
SID
OID

73
Q

How does SID effect resolution

A

Inc SID = Inc resolution - increasing SID creates less penumbra

74
Q

How does OID effect resolution

A

Inc OID = decreases resolution - due to penumbra

75
Q

How does FSS affect resolution

A

Increased FSS = decreased resolution - the bigger the FSS, the more penumbra

76
Q

Where is umbra

A

Inside penumbra - inner edge

77
Q

How does motion effect resolution

A

Increase motion = decrease detail

78
Q

How do you combat motion

A

Decrease exposure time

79
Q

Misrepresentation of the size or shape of the structure

A

Distortion

80
Q

What are types of distortion

A

Magnification
Elongation
Foreshortening

81
Q

Can you magnify & minimize objects on an image

A

No - only magnify

82
Q

How does magnification effect resolution

A

More magnified it is - the less detail you have

83
Q

How does SID effect magnification & detail

A

Increased SID - decreases magnification - increase detail

84
Q

How does OID affect magnification and detail

A

Increased OID - increased magnification - decreased detail

85
Q

How do you calculate size distortion

A

Magnification = SID/SOD

86
Q

Projects object to be longer than appears

A

Elongation

87
Q

Projects object to be shorter than appears

A

Foreshortening

88
Q

When is an object elongated

A

When the tube or IR is improperly aligned

89
Q

When is an object foreshortened

A

Only when the part is improperly aligned

90
Q

Does angulation of the tube affect SID

A

Yes & will cause a decrease in IR exposure

Physics 2 (6 decks)

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