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Radiologic Physics > for the final > Flashcards

for the final Flashcards

(65 cards)

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1
Q

sampling breaks an image into _____

A

pixels

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2
Q

a byte consists of ______ bits

A

8

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3
Q

bit depth determines the imaging systems _____

A

contrast resolution

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4
Q

as spatial frequency increases, spatial resolution _____

A

increases

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5
Q

as matrix size gets bigger, spatial resolution _____

A

increases

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6
Q

a 4-bit system would display ___ shades of gray?

A

16

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7
Q

digital fluoroscopy systems with hybrid capabilities use both _____

A

temporal and energy subtraction

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8
Q

the computed radiography image has

A

Wide exposure latitude and improved contrast resolution

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9
Q

the dynamic range determines the degree of _____ in the image.

A

contrast resolution

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10
Q

an increase in mAs

A

effect on x-ray energy: none
x-ray intensity: increased

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11
Q

an increase in kVp

A

effect on x-ray energy: increased
x-ray intensity: increased

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12
Q

an increase in distance

A

effect on x-ray energy: none
x-ray intensity: reduced

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13
Q

an increase in filtration

A

effect on x-ray energy: increased
x-ray intensity: reduced

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14
Q

the number of gray shades that an imaging system can reproduce is called its

A

dynamic range

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15
Q

each pixel of information in the CT image contains numerical information in ____ units

A

Hounsfield

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16
Q

the CT scanner must be calibrated so that the CT number for water is zero?

A

True

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17
Q

a pixel is

A

2-d image cell

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18
Q

as signal-to-noise increases, image quality

A

increases

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19
Q

if an image receptor has a high probability of interacting with the x-ray beam, then it

A

DQE - detective quantum efficiency

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20
Q

the ability to distinguish different shades of gray or brightness levels is called?

A

contrast resolution

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21
Q

as spatial resolution increases, lp/mm

A

increases

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22
Q

currently, the imaging modality with the highest spatial resolution

A

mammography

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23
Q

when doing soft tissue radiography, the differential absorption between _____ and _____

A

glandular;fat;muscle

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24
Q

Which has the lowest spatial resolution?

A

Nuclear Medicine or Sonography

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25
image noise limits
contrast resolution
26
Which of the following is a high contrast modality.
C. A. CT B. MRI C. radiography D. All of the above
27
the highest occupational exposure of diagnostic x-ray personnel occurs during
fluoroscopy
28
In digital radiography images are made up of discrete picture elements called?
pixels
29
the greater the dynamic range, the better the contrast resolution.
True
30
computed tomography has better ______ resolution than radiography.
contrast
31
For the digital image, the grid of rows and columns is called
matrix
32
The process of creating a series of pixels is called?
sampling
33
increasing the sampling rate...
increases spatial resolution
34
In digital radiography, spatial resolution is improved with increased
matrix size
35
The larger the voxel the ___________ the spatial resolution.
voxel size doesn't affect
36
Spatial frequency is used to describe the quality of spatial resolution in terms of _____________
line pairs
37
image detail is also called
spatial resolution
38
Of all radiographic imaging systems, _____________ has the best contrast resolution
CT has the best contrast resolution of all x-ray imaging systems because of x-ray beam collimation and the resultant reduction in scatter radiation
39
The image intensifier improved fluoroscopy by increasing
image brightness
40
The _______ in the retina are stimulated by _______ light; the _______ are stimulated by _______ light.
rods, low; cones, bright
41
The principal drawback of the first-generation CT scanner was the _______________
long scanning time
42
The third generation of CT scanners allowed for further reduction in _____________
scanning time and scattered radiation
43
CT imaging has excellent ______________ because of the narrow beam collimation
contrast resolution
44
Each sweep of the source-detector around the body during CT is called a __________
translation
45
As discussed in class, an advantage of digital fluoroscopy is it ________________ patient radiation dose
decreases
46
Noise can affect image quality in what way?
decreased contrast resolution
47
As image noise decreases, contrast resolution.......
increases
48
Quantization is the same as sampling.
False
49
As DQE is increased, the amount of radiation necessary to produce an image ______________
decreases
50
Bit depth determines the imaging systems ......
contrast resolution
51
DF have faster image acquisition and _______ to enhance image contrast.
post processing
52
The higher the spatial frequency, the ______ the spatial resolution
HIGHER
53
Select all of the following which can image in 'realtime'?
fluoroscopy and sonography
54
An imaging system bit depth determines what aspect of image quality?
contrast resolution
55
Perfusion is associated with which imaging modality?
SPECT
56
A gamma camera records...
gamma rays
57
The only difference between x-rays and gamma rays is their ____.
origin
58
Which modality utilizes rectangular pixels?
MRI
59
Perfusion imaging is typically done by which modality?
SPECT
60
Of the following, which is the dominant radioisotope used in NM?
technicium
61
Today, new MR scanners are typically
3.0 Tesla
62
Which of these are contrast materials/media for radiography and CT?
barium and iodine
63
more shades of gray is
better contrast resolution
64
Requires the highest spatial resolution of ALL imaging modalities
Mammography
65
____ resolution image loses detail; _____ resolution image shows detail
low; high

Radiologic Physics (6 decks)

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