Unit 2 Quality Factors III: Details and Distortion Flashcards

1
Q

Spatial Resolution

A

Degree of sharpness of structural lines in a radiographic image

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2
Q

Distortion

A

Misrepresentation of the size shape of the part being examined

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3
Q

Controlling factors for Recorded Details

A

-Geometric Factors: Focal Spot Size, Imaging Distances
-Image Receptor: Equipment Speed
-Motion: Patient movement, Equipment movement

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4
Q

Controlling factors for Distortion

A

Geometric factors: Imaging Distances, Part/IR/CR Alignment

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5
Q

Does a small or large Focal Spot size produce images with better detail?

A

Small

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6
Q

Spatial Resolution is improved at a ______ SID

A

Long

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7
Q

________ angle produces higher spatial resolution

A

Smaller

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8
Q

Penumbra

A

-Image blur, not detailed/sharp

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9
Q

How do you asses exposure?

A

With the S number

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10
Q

Penumbra Formula

A

GU = FS (OID)
————
SOD

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11
Q

An increased SID = ___________ spatial resolution
A decreases SID = ___________ spatial resolution

A

Increased;
Decreased

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12
Q

Source to Object Distance (SOD) equation

A

SID-OID = SOD

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13
Q

Screen Speed

A

Describes how sensitive the IR is to radiation
-Higher Speed = More Sensitive to radiation = Less radiation needed to produce quality images

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14
Q

What is the trade off for higher screen speed?

A

Reduced Spatial Resolution/Detail at higher speeds

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15
Q

Spatial Resolution is measured using

A

Line pair test tool

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16
Q

Line pair test tool

A

-Measures Focal Spot resolution
-More visible line pairs = better spatial resolution

17
Q

Types of Motion

A

-Voluntary:
• Under direct control of patient
• Communication
-Involuntary:
• Not under conscious control of patient
• Reduced Exposure times & Immobilization
-Equipment:
• Ensure equipment is stable for exposure

18
Q

How do you reduce exposure time for Involuntary Motion

A

-Increase mA, cut down time
-Increase kVp by 15%

19
Q

RECORDED DETAIL VS. VISIBILITY OF DETAIL

A

Recorded detail:
• FS
• SID/OID
• Screen Speed
• Motion

Visibility of detail:

• Scatter
• Artifacts

20
Q

If an image has good spatial resolution, what 2 factors might cause reduced visibility of detail

A

Scatter and Artifact

21
Q

What is the ONLY possible size distortion in radiography?

A

Magnification

22
Q

Size Distortion

A

• Misrepresentation of the size of an object
• Magnification

23
Q

Is minimization possible for magnification/distortion?

24
Q

Size distortion controlling factors

A

• SID
• OID

25
Magnification is reduced at a _______ SID
Long
26
Magnification is increased at a _______ SID
Short
27
Magnification Factor Equation
M = I — 0 I = SID or Image Size 0 = SOD or Obiect Size M = Magnification Factor
28
SHAPE DISTORTION
Elongation: Project objects so they appear longer than they are -Tube and IR not aligned Foreshortening: Project objects so they appear shorter than they are -Part and IR not aligned