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2016FA PHYSICS (K. Greene) > EXAM #6 Tutor Questions > Flashcards

EXAM #6 Tutor Questions Flashcards

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1
Q

• Overall resolution for imaging is measured as physicists as

A

MTF

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2
Q

• If in the remnant beam signal, what can reduce subject contrast and gray scale

A

Scatter

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3
Q

• How do you measure spatial frequencies

A

LP/mm

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4
Q

• Mathematically, the ratio of an images recorded contrast to the real subject contrast defines what

A

o MTF, closest to one as possible

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5
Q

• Which of the following is NOT a variable affecting sub contrast in remnant beam

A

o Focal spot

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6
Q

• For the computer to process an image, analog to digital is composed by a device called

A

o Analog to digital converter

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7
Q

• In general, digital imaging terms, brightness is what?

A

o Window level

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8
Q

• 1000x1000 matrix? How many pixels?

A

o 1mil pixels

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9
Q

• Compared to Work station, display stations can typically have

A

o Less resolution

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10
Q

• The selection of a narrow window width

A

o Increase contrast

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11
Q

• Dead pixels in the image is caused by failure of dead DELS

A

o Interpolation

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12
Q

• Flat field uniform corrections because of all the following except for what?

A

o Data clipping

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13
Q

• List of pixel values that make up a histogram, it’s called a permanent what?

A

o LUT

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14
Q

• A sub matrix that is passed over the original, executing a mathematical function is called what?

A

o Kernel

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15
Q

• Pattern recognition software is used for what?

A

o Segmentation

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16
Q

• Normalization is best described as the computer attempt to

A

o Make digital image look like a film image prior to any post processing

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17
Q

• Which of the following can a comp processing not do?

A

o Cannot change the pixel count

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18
Q

• Histogram correction errors are

A

o Not necessarily related to the radiographic technique used

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19
Q

• Histogram analysis failure is less common with DR, than CR, because DR algos include what

A

o Only the exposed DELS

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20
Q

• Histogram is the result when a digital image is sorted by

A

o Values contained by pixel

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21
Q

• Low freqs represent what?

A

o Large objects

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22
Q

• If you have dual energy subtraction, you either have variable filters or variable kVp

A

o High and low energy images (1 for bone and 1 for soft tissue)

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23
Q

• For all digital image systems, a restriction for lower limit for exposure

A

o Mottle

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24
Q

• Just as in conventional radiography, the what must have a high SNR

A

o Remnant beam

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25
Q

• In CR, substantial fog densities between 2 projections on the same plate can cause what

A

o Segmentation failure

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26
Q

• In any CR system, underexposure causes visible what?

A

o Mottle

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27
Q

• In the digital age, the main role of radiographic technique is what?

A

o Ensure proper SNR

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28
Q

• Which of the following is digital processing least capable of correction

A

o Pre-fogging on the CR plate

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29
Q

• Digital imaging system cannot compensate what

A

o Too low kVp

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30
Q

• Misunderstandings about radiographic technique, combined with broad exposure latitude in digital imaging systems

A

o Dose creep

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31
Q

• On a DR system. The field size for each image is what

A

o Adjusted by radiographer

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32
Q

• The weakest link in a radiographic imaging system chain

A

o Image display system

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33
Q

• How do you distinguish adjacent details from each other

A

o Visibility AND geometric

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34
Q

• What is not a form of image noise

A

o Signal

35
Q

• What size is the smallest object that can be resolved by 2.5LP/mm

A

o Object

36
Q

• As line pairs of a resolution template become smaller and closer together the overlapping of their penumbra causes loss of

A

o Contrast

37
Q

• When the pixels of a digital imaging systems are small than the object in the focal spot, what’s the limiting factor for spatial resolution

A

o Focal spot size

38
Q

• Which is the following is not a variable affecting noise

A

o Exposure time

39
Q

• For radiography the brightness of a certain pixel within the image matrix of a digital image is related to what

A

o Attenuation

40
Q

• In general, digital imaging terms, the range of gray scale is what?

A

o Window width

41
Q

• If you have a 12 bit, ADC each pixel will have what?

A

o 2^12

42
Q

• The larger the number of pixels in a matrix, what?

A

o Resolution

43
Q

• As a displayed FoV is increased in size, spatial resolution or sharpness does what?

A

o Decreases

44
Q

• The increased contrast res of digital imaging systems, allows demonstration of tissues with inherent subject contrast as low as what?

A

o 1%

45
Q

• Which of the following would result in a displayed image that would be brighter?

A

o Decreased window level

46
Q

• The general term for brightness and contrast is what?

A

o Windowing

47
Q

• The term pre-processing is for the computer algos which represent what?

A

o Correct for image flaws in image acquisition

48
Q

• In the active matrix array of a DR receptor plate, variations in alignment for multiple electronic amps and differences in resistance for varying lengths of wires coming from the hundreds of DELS

A

o Gain offsets

49
Q

• Which of the following flaws are unique by CR but not DR

A

o Light guide variations

50
Q

• Background exposure to a CR cassette and small amount of electronic current flowing through a DR system when no exposure is being taken

A

o Dark noise

51
Q

• In a digital histogram graph, the vertical height along the plotted curve is against the y-axis, what?

A

o Number of pixels per value

52
Q

• Which of the following systems req the greatest amount of preprocessing?

A

o DR

53
Q

• On an image histogram, an unusual spike to left is what?

A

o Metallic objects

54
Q

• In an algo designed to accentuate soft tissue densities will locate the VOI on a histogram

A

o Father to the right

55
Q

• Comp distinguishes anatomy of interest from background from what

A

o Auto field recognition

56
Q

• Segmentation failure is what?

A

o Partition pattern recognition

57
Q

• For a large abdomen which completely covers the image plate, the histogram will appear how?

A

o No spikes

58
Q

• Exposure field recog is normally done as what

A

o Histogram analysis

59
Q

• The steeper the S-curve, the what?

A

o Higher image contrast

60
Q

• The bins of data from the acquired image to be used for rescaling

A

o S-values

61
Q

• Because the range of the Q scale, is outside the range of the discernment of the human eye this allows for what of the image

A

o Windowing

62
Q

• Rescaling the image is primary the process of ____ which is the acquired data set

A

o Algebraically relabeling it

63
Q

• Histogram analysis can fail to ID key landmarks when a bizarre data set results in an unexpected what?

A

o Histogram shape

64
Q

• All of the following are general domains except what?

A

o Amplitude

65
Q

• Sorting an image by the location of its pixels results in a _____

A

o Matrix

66
Q

• Point area in global operations are all sub-cats for what domain

A

o Spatial

67
Q

• An example of an area of operation would be what?

A

o Zoom

68
Q

• Whenever a displayed image is windowed, which of the following default processes is reapplied

A

o Graduation processing

69
Q

• In dynamic range of the processing system is too limited, it is possible for what to occur when the displayed image is later windowed?

A

o Clipping

70
Q

• From selective midpoint in various gray levels, lighter areas in the image are progressively darkened while darker areas are progressively lightened, this describes what?

A

o Dynamic range compression

71
Q

• For the graduation processing curves developed by Fuji, the shape of a particular which a particular algebraic formula generates, is represented as the perimeter what?

A

o GT

72
Q

• Noise in the image caused by electronic malfunctions is normally periodic, occurring at regular intervals across the image, rather than random, such as quantum mottle. It’s best eliminated using what?

A

o Processing in a frequency domain

73
Q

• A small core matrix of mathematical values which is passed through the image matrix, multiplying the value of each pixel sequentially by the numbers in it

A

o Kernel

74
Q

• High-pass filtering only allows what to pass through?

A

o High frequency objects, small objects

75
Q

• The math method by which the complex wave representing one line of digital image can be broken down into a set, the individual wavelengths that make it up is known as the what?

A

o Fourier method

76
Q

• Dual energy subtraction takes average of what differences between soft tissues and bones

A

o Photoelectric

77
Q

• What across the board adj. in radiographic techniques is suggested to allow for CR operation at a 400 speed class, reduced pt exposure, avoid mottle

A

o Increase 15% kVp

78
Q

• If a dept. chooses to operate their CR/DR system at a 200 speed class, what general adj. in tech should be made form a 400 speed

A

o Double the technique

79
Q

• How much overexposure is required before oversaturation occurs?

A

o 8-10 times more

80
Q
  • Which of the following states is true regarding CR

* Which is false?

A

TRUE = Digital processing is able to compensate for scatter

FALSE = Scatter always results in dark images

81
Q

o For CR, as a general rule of thumb, what % of the receptor plat needs to be exposed to prevent errors

A

o At least thirty percent needs to exposure

82
Q

o Which of the following has the least amount of effect on scatter?

A

o kVp

83
Q

o Which of the following affects displayed image contrast?

A

o Windowing, gradation processing, rescaling

84
Q

o The increased exposure latitude includes all of the following options except?

A

o Using low kVp

2016FA PHYSICS (K. Greene) (13 decks)

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