What is detective quantum efficiency (DQE)

Ability of an IR to capture information

A single point of color of a larger image, A picture element, A fundamental unit of a digital image, A smartphone made by Google

contrast resolution is a digital systems ability to

show small differences in gray leves

What is spatial resolution?

The ability of an imaging system to render small objects

Exposure index is defined as:

a numerical value to indicate exposure to the detector / IR

The optical mirror in the reader

directs the laser beam to the imaging plate surface.

Collimation to a smaller area:

decreases Compton interactions.

Grid frequency is defined as:

The amount of lead in the grid (the number of lead strips per cm/in)

Which of the following does determine PSP resolution?

Pixel size, Number of pixels, Phosphor layer thickness

AKA Normalization. Re-mapping brightness and grayscale of the digital image

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Ch 4 Digital Review

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Questions 90

Answers

1
The use of a grid will
reduce the effect of scatter radiation on the radiograph
increase contrast
all of the answers
reduce film fog
2
Less kVp is needed with conventional radiographic screens than is necessary for PSP systems.
False
True
3
PSP phosphor speed and radiographic film speed are always equivalent.
True
False
4
The analog to digital converter
Makes the electrical signal understandable to the computer
All of the above
Determines the contrast resolution of the system
Determines the image matrix
5
The active portion of the computed radiography imaging plate (IP) is the
C. silver halide crystals.
D. rare earth phosphor.
B. photostimulable phosphor.
A. intensifyng screen phosphor.
6
Which of the following require more critical beam centering
low ration grids
parallel grids
focused grids
low frequency grids
7
What is detective quantum efficiency (DQE)
Ability to tell differences in grays
Ability of an IR to capture information
Ability to tell difference between contrasts
8
A pixel is ___.
A single point of color of a larger image
A picture element
A fundamental unit of a digital image
A smartphone made by Google
9
It is acceptable to replace collimation with shuttering.
True
False
10
Ideally we would like to have a modulation transfer function value of:
2
1
.75
.5
11
contrast resolution is a digital systems ability to
show small differences in gray leves
record noise interference
allow lower KVP and higher MAS values
separate structures from noise
12
Quantum mottle is caused by?
excessive mAs
excessive kVp
insufficient distance
insufficient mAs
13
When insufficient light is produced by the imaging plate phosphor, the image will appear:
grainy
dark
14
The phosphor layer is made of phosphors from the ______ family
calcium fluorohalide
barium fluorohalide
barium sulfate
halide calcium
15
In the PSP reader, a laser scans the imaging plate in a:
random pattern
raster pattern
circular pattern
horizontal pattern
16
Increased collimation =
Decreased exposure
Increased exposure
Increased image contrast
Decreased image contrast
17
Less kVp is needed with conventional radiographic screens than is necessary for PSP systems.
False
True
18
The size of the pixel is determined by the
byte
matrix
bit depth
19
Grid lines projected onto the imaging plate will not interfere with the image.
True
False
20
The k-edge of phosphor imaging plates ranges from ____keV.
100-110
40-60
30-50
20-30
21
During laser beam formation, both ends of the laser reflect energy back and forth so that the atoms
absorb each other.
lose energy.
create x-ray energy.
bombard each other.
22
It is acceptable to replace collimation with shuttering.
True
False
23
What is the typical grid frequency range?
30-100 lines/inch
100-500 lines/inch
40-200 lines/inch
60-150 lines/inch
24
A higher ratio grid
increases contrast
absorbs more scatter radiation
all of the answers
requires increased patient dose
25
What is spatial resolution?
portion of the image forming xrays that represent anatomy
The ability of an imaging system to render small objects
ability of an imaging system to render different contrasts
ratio of image to object as a function of spatial frequency
26
Grid lines projected onto the imaging plate will not interfere with the image.
True
False
27
Detective Quantum Efficiency (DQE)
all of the above
how efficiently a system converts the x-rays into a useful output image
High DQE produces higher quality images at a lower dose
measurement of the percent of x-rays that is absorbed through the IR
28
PSP imaging plates are erased by flooding the plate with:
light
electrons
radiation
phosphors
29
Which of the following does not determine PSP resolution?
pixel size
the number of pixels
laser scan speed
phosphor layer thickness
30
Selection of the incorrect body part from the examination menu may result in?
proper density and contrast
no difference in image sharpness
image misinterpretation
no image
31
Exposure index is defined as:
the numerical values of the pixels
the difference in image brightness
the response of the IR to radiation falling on it
a numerical value to indicate exposure to the detector / IR
32
The optical mirror in the reader
Produces lava
Creates laser beam
directs the laser beam to the imaging plate surface.
33
Cracks in the imaging plate appear as areas of _______ on the image?
All of the above
densities
radiolucency
artifact
34
The PSP imaging plate does not require periodic erasure because of its ability to record background radiation.
True
False
35
The purpose of the barcode label is to match the image information with the
Imaging plate
Patient identifier
Patient Number
36
Collimation to a smaller area:
decreases resolution.
decreases Compton interactions.
increases amount of tissue irradiated
increases scatter
37
mAs directly controls all of the following except:
quantity of x-rays produced
quality of x-rays produced
IR exposure
intensity of x-ray beam
38
The process of scanning the moving imaging plate in known as
digitization
translation
raster scanning
transition
39
Grid frequency is defined as:
How often a grid is used
The amount of contrast improvement factor
The amount of lead in the grid (the number of lead strips per cm/in)
The same as grid ratio
40
The number of pixels making up the digital image is the
Pixel pitch
Pixel depth
Field of view
Matrix size
41
A focused grid.......?
Has angled strips.
Makes you glow in the dark if you stand in the wrong place.
Has variated strips.
Has parallel strips.
42
The _________ layer of the plate is considered the active layer.
support
protective
phosphor
light reflective
43
PSP phosphor speed and radiographic film speed are always equivalent.
False
True
44
Which of the following does determine PSP resolution?
Pixel size
Laser scan speed
Number of pixels
Phosphor layer thickness
45
Which of the following should be considered when selecting the PSP cassette?
type and speed.
none of these.
size and speed.
size and type.
46
Improper PSP erasure can be caused by:
too little time in erasure chamber
loss of lamp intensity
burned out bulbs
all of the above
47
coherent light is formed by the laser because the photons
travel in all directions
are at varying frequencies
travel in the same direction
are at the right angle
48
define pixel
picture elongation
picture equivalent
picture equation
picture element
49
Rescaling?
the incidence that a particular exposure value has occurred.
AKA Normalization. Re-mapping brightness and grayscale of the digital image
amount of exposure
graphical representation of numerous shades of gray within an image
50
The PSP plate is erased:
Manually by selecting the proper eraser method
By flooding it with bright light
After the plate is read
All of the above
51
Shuttering is a replacement for pre exposure collimation
True
False
52
Grid use for PSP examinations is more critical than in film/screen radiography because CR:
examination produce more scatter.
imaging plates record less scatter.
examinations require much higher kVp values.
imaging plates record more densities.
53
The amount of detail present in any image is known as ______ resolution.
density
contrast
optical
spatial
54
Quantum mottle is caused by?
insufficient distance
insufficient light
excessive mAs
excessive kVp
55
What is a matrix?
Number of bits that control the pixel brightness
A small, usually square, "picture element"
Combination of rows or columns
56
If SID is doubled what may be said about receptor exposure?
Receptor exposure doubles
Receptor exposure is reduced by one half
Receptor exposure is reduced to one fourth
Receptor exposure is reduced by by new mas^2
57
range of kVp values for CR (PSP)
65 kVp to 105 kVp
60 kVp to 110 kVp
55 kVp to 125 kVp
45 kVp to 120 kVp
58
The imaging plate layer that absorbs stimulating light and reflects emitted light is the ______ layer.
backing
reflective
color
active
59
Felt material protects against static buildup, dust collection and mechanical damage to imaging plate
True
False
60
Milliampere-seconds (mA-s) is selected for the
amount of penetration needed.
longest time possible.
shortest time possible.
number of electrons needed.
61
What does detective quantum efficiency (DQE) do?
Collects data to help keep patient exposures low
Determines the matrix size of the digital image
Represents the K-shell binding energy of the x-ray photon
Predicts radiation exposure needed to produce optimal image
62
Collimation to a smaller area:
decreases scatter.
increases amount of tissue irradiated.
decreases resolution.
63
What is Modulation Transfer Function (MTF)?
ratio of image to object; spatial resolution
Inverse square law
Luminous flux
Dynamic Range
64
The wavelength of the PSP reader laser is ______ nm.
366
636
336
633
65
Cracks in the imaging plate can be caused by
excessive kVp.
removing and replacing the plate in the reader.
scatter through the back of the cassette.
improper erasure.
66
The higher number of pixels in a matrix, the:
lower the spatial resolution
higher the spatial resolution
decreased amount of magnification
increased amount of magnification
67
What do the parallel or focused grids do?
moves electrons from cathode to anode
decrease tube heat
help decrease scatter radiation
limit motion artifact
68
Shuttering, a post exposure image manipulation technique, is ____
added to the screen image
changes the amount of scattter
placed on the cassette
placed on the patient
69
Translation is the process of scanning the moving imaging plate
True
False
70
When the imaging plate is irradiated, stimulated electrons enter the ______ layer.
Conductive
Active
Support
71
Each light photon is assigned a number during:
digitization
amplification
laser scanning
sampling
72
The active layer of the imaging plate traps______?
Electrons
barium fluorohalide
X rays
light
73
To reduce patient exposure, post exposure shuttering can be used:
false
true
74
Focused grids are designed in relation to...
SID
grid ratio
mAs
kVp
75
The PSP cassette is backed by aluminum that:
reflects x-rays
absorbs backscatter x-rays
captures the image
transmits x-rays
76
A look up table maps
latent images
grayscale values
subject contrasts
densities
77
The wavelength of the PSP reader laser is ______ nm.
336
633
636
366
78
how is pixel size determined
Matrix + FOV
Matrix/FOV
FOV/Matrix
FOV x Matrix
79
Right and Left markers should be placed on the
thyroid protector
IR
patient
80
shuttering the digital image will reduce the exposure to the patient
False
True
81
It is acceptable to replace collimation with shuttering.
False
True
82
The range of kVp that can be used with PSP systems is
55-130.
65-120.
75-130.
45-120.
83
The laser scans the imaging plate in a ______ pattern.
horizontal
raster
circular
random
84
Modulation Transfer Function is:
a measure of the ability of an imaging system to preserve signal contrast
the controlling factor of contrast resolution
a function of exposure
a function of pixel density
85
Kilovoltage peak (kVp) should be chosen
to provide the least contrast possible.
for the type and amount of contrast desired.
To provide penetration
86
Grid ratio is defined as:
The ratio of the distance between the strips over the height of Pb strips
The thickness of the Pb strips / by the thickness of the Al interspaces
The ratio of the height of lead strips over the distance between the strips
The ratio of the # of lead strips to the space between them
87
A histogram is
a report on exposure values
another name for exposure indicator value
a graphic representation of x-ray exposure
an examination of the chest
88
Intermittent extraneous line patterns are _____ artifacts.
Printer
Plate reader
Imaging plate
Processor
89
What layer sends light in a forward direction?
The backing layer
The color layer
The conductive layer
The reflective layer
90
Histogram is
History of exposure values for the entire hospital
History of exposure values for this machine
History of exposure values for this exposure ONLY

Ch 4 Digital Review Flashcards | StudBud