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2403 Physics > Chapter 9 Exam > Flashcards

Chapter 9 Exam Flashcards

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1
Q

A quality radiograph must include:
a. Accuracy of structural lines displayed
b. Minimal sharpness
c. Visibility of anatomic structures
d. All of the above

A

d. All of the above

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2
Q

Visibility factors of a quality radiograph include:
a. Brightness
b. Spatial resolution
c. Contrast
d. a and c

A

d. a and c

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3
Q

Which of the following results in a poor-quality digital image because of improper processing due to extreme over exposure to the image receptor
a. Distortion
b. Saturation
c. Quantum noise
d. Modulation transfer function

A

b. Saturation

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4
Q

What feature provides a numeric value indicating the level of radiation exposure to the digital image receptor?
a. Exposure indicator
b. Saturation
c. Pixel density
d. Grayscale

A

a. Exposure indicator

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5
Q

Anatomic tissues that attenuate the x-ray beam equally are said to have:
a. Quantum noise
b. High contrast
c. Low subject contrast
d. Less unsharpness

A

c. Low subject contrast

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6
Q

An imaging system that can resolve 10 Lp/mm instead of 6 Lp/mm is said to have:
a. Less distortion
b. More unsharpness
c. More distortion
d. Improved sharpness

A

d. Improved sharpness

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7
Q

Unwanted scatter exposure to the image receptor will likely increase:
a. Unsharpness
b. Brightness
c. Fog
d. Saturation

A

c. Fog

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8
Q

What is defined as “the range of exposure intensities an image receptor can accurately detect”?
a. Resolution
b. Contrast
c. Window level
d. Dynamic range

A

d. Dynamic range

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9
Q

For a given field of view (FOV), a _____ matrix size will result in _____ pixels
a. Large, fewer
b. Large, more
c. Small, more
d. None of the above

A

b. Large, more

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10
Q

In digital imaging, which of the following determines the range of grayscale available for display?
a. Pixel density
b. Matrix size
c. Pixel bit depth
d. Exposure indicator

A

c. Pixel bit depth

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11
Q

During digital image display, the contrast can be lowered (decreased) by increasing ______
a. Pixel density
b. Grayscale
c. Window level
d. Window width

A

d. Window width

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12
Q

The ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly defines:
a. Dynamic range
b. Grayscale
c. insufficient detective quantum efficiency
d. Contrast resolution

A

d. Contrast resolution

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13
Q

Increasing the displayed field of view (FOV) for a fixed matrix size will result in:
a. Decreased pixel pitch
b. Increased pixel size
c. Decrease pixel size
d. Increased pixel bit depth

A

b. Increased pixel size

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14
Q

The visibility of anatomic structures is increased with:
a. Increased contrast-to-noise ratio (CNR)
b. Increased quantum noise
c. Increased signal-to-noise (SNR)
d. a and c only

A

d. a and c only

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15
Q

An imaging system with a higher detective quantum efficiency (DQE):
a. Is more efficient in converting x-ray exposure to a quality image
b. Produces images with decreased spatial resolution
c. Can display anatomic structures with less distortion
d. Produces images with decreased contrast resolution

A

a. Is more efficient in converting x-ray exposure to

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16
Q

Double exposing an image receptor will likely result in:
a. Pixel pitch
b. Foreshortening
c. Increased quantum noise
d. Image artifact

A

d. Image artifact

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17
Q

FOV/Matrix/pixel calculation

A

Pixel size (mm) = FOV (cm) / matrix size (mm)

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18
Q

the amount of luminance (light emission) of a display monitor

A

image brightness

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19
Q

The dynamic range in digital imaging is _____

A

linear

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20
Q

A _____ ______ _____ is only useful if the displayed image brightness can be optimized for human perception

A

wide dynamic range

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21
Q

The ability of the system to distinguish between small objects that attenuate the x-ray beam similarly

A

Contrast Resolution

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22
Q

a control that adjusts the contrast

A

Window width

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23
Q

the image has lower contrast, or more shades of gray

A

Wide window width

24
Q

the image has higher contrast, or fewer shades of gray

A

Narrow window width

25
Q

sets the midpoint of the range of brightness levels visible in the image, changing the this on the monitor allows the image brightness to be increased or decreased throughout the entire range of brightness levels

A

Window level

26
Q

When an image is underexposed excessive _______ ______ may be visible

A

quantum noise

27
Q

differential absorption, difference in brightness levels

A

Contrast

28
Q

the combined result of multiple factors associated with the anatomic structure, quality of the radiation, capabilities of the image receptor

A

Radiographic contrast

29
Q

refers to the absorption characteristics of the anatomic tissue radiographed and the quality of the x-ray beam

A

Subject contrast

30
Q

What makes a good radiograph?

A

Accurately represents the anatomic area of interest. The characteristics evaluated for image quality are density or brightness, contrast, recorded detail or spatial resolution, distortion, and noise

31
Q

The brightness of the image can be adjusted using the window level on the monitor to make the image looks better

A

Monitor brightness

32
Q

Provides a numeric value indicating the level of radiation exposure to the digital image receptor

A

Exposure indicator

33
Q

Distance measured from the center of a pixel to an adjacent pixel

A

Pixel pitch

34
Q

Number of pixels per unit area

A

Pixel density

35
Q

Measure of the imaging system’s ability to display the contrast of anatomic objects varying in size, measured 0 and 1.0

A

Modulation Transfer Function

36
Q

in Modulation Transfer Function 0 =

A

no difference in brightness level

37
Q

in Modulation Transfer Function 1.0 =

A

maximum difference in brightness levels

38
Q

Modulation Transfer Function equation

A

MTF = (maximum intensity - minimum intensity) / (maximum intensity + minimum intensity)

39
Q

Adds unwanted exposure to the radiographic image as a result of compton interactions
Decreases contrast

A

Scatter

40
Q
  • A concern in digital imaging, photon-dependent, is visible as brightness fluctuations on the image
  • The fewer the photons reaching the IR to form the image, the more this will be visible on the digital image
  • Fix this by increases mAs
A

Quantum noise

41
Q
  • A method of describing the strength of the radiation exposure on the comparison to the amount of noise apparent in the digital image
  • Increasing this means that the strength of the signal is high compared to the amount of noise
  • Increasing this will improve the quality of the digital image
A

Signal-to-Noise Ratio (SNR)

42
Q
  • Any unwanted brightness level on a radiographic image
  • Can result from doubling exposing and IR, improper use of equipment, or patient clothing
A

Artifacts

43
Q

results from the radiographic misrepresentation of either the size (magnification) or the shape of the anatomic part

A

Distortion

44
Q

term used to evaluate accuracy of the anatomic structural lines
- A radiographic image cannot be an exact reconstruction of the anatomic structure
- Diagnostic quality is achieved by maximizing resolution and minimizing image distortion

A

Spatial resolution

45
Q

A measurement of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image

A

Detective Quantum Efficiency (DQE)

46
Q

The higher the DQE of a system, the _____ the radiation exposure to produce a quality image, thereby _________ patient exposure

A

lower, decreasing

47
Q

refers to an increase in the image size compared with the object’s actual size

A

Size distortion

48
Q

Shape distortion can appear in two different ways radiographically:

A

elongation & foreshortening

49
Q

images of objects that appear longer than the true objects

A

elongation

50
Q

images that appear shorter than the true objects

A

foreshortening

51
Q

high-contrast =

A

short scale, fewer gray tones

52
Q

low-contrast =

A

long scale, many gray tones

53
Q

An imaging system that can resolve a greater number of line pairs per mm (higher spatial frequency) has increased ______ _______

A

spatial resolution

54
Q

A pixel pair can be equivalent to a ____ ____

A

line pair

55
Q

Coherent scatter =

A

radiationless scatter

56
Q

_______ ________ is expressed in line pairs per mm of pixel size

A

Spatial frequency

57
Q
A

2403 Physics (8 decks)

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