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~RADT 171 > Image Analysis > Flashcards

Image Analysis Flashcards

1
Q

A post-processing manipulation that can be added to digital projections as a means of helping the viewer to better evaluate contrast resolution in the selected area is a:

A

Contrast mask

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2
Q

Additive disease processes that would require at least a 35% increase in mA include all of the following except:

A

Paget’s disease

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3
Q

T/F: Using the smallest possible IR and covering at least 50% of it is a guideline for producing optimal image histograms

A

False

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4
Q

All of the following are true about histogram analysis errors except:
a. histogram analysis errors result in erroneous exposure indicator numbers.
b. selecting the wrong body part or projection in the workstation menu will cause a histogram analysis error.
c. fog values outside the exposure field, but included in the VOI, do not cause widening of the histogram.
d. histogram analysis errors may occur as a result of poor central ray centering.

A

C

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5
Q

All of the following are true about quantum noise except:
a. quantum noise is demonstrated as a blotchy appearance on the image.
b. quantum noise is visualized when the exposure indicator number is higher than the ideal exposure values.
c. quantum noise results in excessive patient dose when present on the image.
d. when present, quantum noise requires an increase in exposure factors to reduce its visualization on the image.

A

B

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6
Q

All of the following are true about windowing except:
a. windowing is referred to as a post-processing manipulation procedure.
b. window level adjustments change the contrast of the image.
c. saving adjusted windowing settings to the PACS system narrows the dynamic range for future viewers.
d. windowing occurs after the image is displayed on the monitor.

A

B

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7
Q

Best practice guidelines for the use of automatic exposure control include all of the following except:
1. set the optimum kV for the body part.
2. set the backup timer to 150% to 200% of the expected manual exposure.
3. set the highest mA station for the focal spot size needed.
4. wide collimation will ensure IR coverage.

A

4

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8
Q

Examples of artifacts that must be accepted include all of the following except
1. pacemakers.
2. dental bridges.
3. pleural drainage tubes secured with safety pins.
4. endotracheal tubes.
5. heart monitoring lines.

A

3 and 5

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9
Q

How many shades of gray can each pixel in a digital matrix display?

A

One

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10
Q

The exposure indicator number represents all of the following except the:
a. measure of dose to the patient.
b. amount of exposure to the patient.
c. amount of light given off by the imaging plate.
d. amount of exposure to the imaging plate.

A

A

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11
Q

What is the location on a histogram graph of fat?

A

Right

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12
Q

What is the location on a histogram graph of bone?

A

Left

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13
Q

Which technical factor listed below is primarily used to regulate density?

A

mAs

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14
Q

Which of the following technical factors is primarily used to regulate subject contrast?

A

kVp

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15
Q

Which of the following is true about image markers?
1. They are radiopaque.
2. They should be reversed before being placed on the IR.
3. They should be positioned as close to the median plane as possible.
4. They will be magnified if positioned on the imaging table or patient.

A

1 and 4

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16
Q

Which of the following may occur as a result of the DI value greater than +3.0?
1. Excessive noise visible
2. Saturation
3. Patient overexposure

A

2 and 3

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17
Q

T/F: A DI of −0.75 reflects insufficient exposure to the IR.

A

False

18
Q

T/F: The deviation index (DI) is a value that reflects the difference between the desired or target exposure to the IR and the actual exposure to the IR.

A

True

19
Q

Which of the following may impact the location and shape of the histogram?
1. Exposure technique
2. Positioning
3. Collimation

A

1, 2 and 3

20
Q

Which of the following is not a numerical value indicating the level of radiation exposure to a digital image receptor (IR)?

A

Window level

21
Q

What process is employed to maintain consistent digital image brightness for over- or underexposure?

A

Automatic rescaling

22
Q

Image artifacts can be caused by
1. dirty CR IPs.
2. low sampling frequency.
3. increased pixel density.

A

1 and 2

23
Q

T/F: Decreasing the displayed FOV for a given matrix size will decrease the size of the pixels and increase spatial resolution.

A

True

24
Q

T/F: A lower signal-to-noise ratio (SNR) improves the quality of a digital image.

A

False

25
Q

______ refers to the range of exposures that should be used to produce a diagnostic image.

A

Exposure latitude

26
Q

Small anatomic detail has:
A. decreased pixel density
B. increased spatial resolution
C. high spatial frequency
D. low signal to noise ratio

A

C

27
Q

Which of the following pixel bit depths would display a greater range of shades of gray to represent anatomic tissues?
A. 8 bit
B. 10 bit
C. 14 bit
D. 16 bit

A

D

28
Q

What is the process of assigning a numerical value to represent a brightness value?

A

quantization

29
Q

Which of the following would improve the spatial resolution of the digital image for a given field of view (FOV)?

A. A fixed matrix size and larger IP
B. A decreased sampling frequency and larger IP
C. A small matrix size and larger pixel size
D. A fixed matrix size and small IP

A

D

30
Q

Which of the following will improve the spatial resolution of the digital image?
A. Decreased sampling frequency and increased sampling pitch
B. Decreased sampling frequency and decreased sampling pitch
C. Increased sampling frequency and increased sampling pitch
D. Increased sampling frequency and decreased sampling pitch

A

D

31
Q

What is a measurement of the efficiency of an IR in converting the x-ray exposure it receives to a quality radiographic image?

A

DQE

32
Q

A higher sampling frequency during CR latent image digitization will:

A

Increase spatial resolution

33
Q
  1. Which of the following would improve spatial resolution?
    A. Small matrix and large pixel size
    B. Decreased pixel density and increased pixel pitch
    C. Large matrix and large pixel size
    D. Large matrix and increased pixel density
A

D

34
Q

If the matrix size is increased for a fixed FOV:

A

the pixel size decreases

35
Q

Window and leveling changes the digital images:

A

Brightness and contrast

36
Q

What increases as matrix size increases?

A

Spatial resolution

37
Q

What digital process alters image brightness and grayscale to improve the visibility of anatomic structures?

A

LUTs

38
Q

T/F: Maintaining a low level of ambient lighting can improve soft-copy viewing of digital images.

A

True

39
Q

Display monitors used for soft-copy viewing of digital images should have __________.
A. increased ambient lighting
B. decreased matrix size
C. high pixel pitch
D. high luminance

A

D

40
Q
  1. Which of the following is not a function during postprocessing of a displayed digital image?
    A. Histogram analysis
    B. Electronic masking
    C. Windowing
    D. Edge enhancement
A

A

41
Q

Wider window width __________.
A. increases brightness
B. decreases brightness
C. increases contrast
D. decreases contrast

A

D

42
Q

What postprocessing technique suppresses image noise?

A

Smoothing

~RADT 171 (10 decks)

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