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Digital Terminology Overview
Modulation Transfer Function is:
Window width controls:
Digital Terminology Overview
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1
Window width controls:
Image brightness
Image contrast
Density
Overall darkness
2
Modulation Transfer Function is:
a function of exposure
the controlling factor of contrast resolution
a measure of the ability of an imaging system to preserve signal contrast
a function of pixel density
3
In PSP imaging, what is prevented by flooding the erased IP with bright light?
noise
image fog
overexposure
ghosting
4
What is a bit?
Number of 2-3
Short for hexadecimal digit
Just like a byte
Short for binary digit
5
which has improved contrast resolution?
more bits per pixel
fewer bits per pixel
6
Which detector uses amorphous selenium
CR detector
Direct detector
Film detector
Indirect detector
7
what is CCD/CMOS
camera image chip; optical images electronic signals
camera class director that control cameras
camera monitor operating system
converts cameras to computers
8
when a PSP is exposed to a laser reader how does it obtain the manifest image?
energy is released & converted to a digital signal
electrons become trapped in the conduction band
a signal is sent to the PACS unit
phosphor atoms are ionized & remain in the conduction band
9
Exposure index is defined as:
the response of the IR to radiation falling on it
a numerical value to indicate exposure to the detector
the difference in image brightness
the numerical values of the pixels
10
PSP is exposed to what color light for erasure of remaining electrons?
Bright White light
Pink fluorescent light
Black fluorescent light
Gray fluorescent light
11
Gain calibration is used to correct flaws in the detector
False
True
12
Amorphous selenium is used
photodector for direct capture cassette-less DR
photoconductor for direct capture cassette-less DR
photoconductor for indirect capture cassette-less DR
photodetector for indirect capture cassette-less DR
13
What is Modulation Transfer Function (MTF)?
Luminous flux
ratio of image to object; spatial resolution
Dynamic Range
Inverse square law
14
Signal-to-noise ratio
Multiples of the fundamental frequency
Adding additional tracks to previously recorded material
The speed of the music
Level of wanted signal compared to level of unwanted noise
15
Barium fluorohalide is used in:
direct DR
PSP plates
the filament
image intensifiers
16
MTF determines _____?
image detail
image density
image size
image contrast
17
The result of low-pass filtering is:
a sharp image
The result of low-pass filtering is:
smoothing
subtraction
18
Window Width controls
Image Contrast
Image Density
19
what is dynamic range?
the degree of sharpness on an image
the difference between various shades of gray on an image
contrast as it's displayed on a digital monitor
black & white shades on an image
20
Amorphous silicon?
the ability to produce light
amorphous selenium
converts light directly to an analog using sensor chip lens or fiberoptics
IDR with TFT technology
21
As collimation _________ , exposure to the IR _________.
increases; decreases
decreases; decreases
decreases; increases
increases; increases
22
A histogram is
a report on exposure values
an examination of the chest
a graphic representation of x-ray exposure
another name for exposure indicator value
23
High signal-to-noise ratio =
high noise= low image quality
high signal= high image quality
24
Window width represents
quality
brightness
detail
shades of gray
25
The barcode label is used by the reader to identify the PSP plate.
True
False
26
The artifact on the image is:
grid tilt
grid lines
grid cut off
motion
27
Pixel pitch refers to the:
angle of the pixel
center of one pixel to another
size of the pixel
tone value of pixels
28
Detective Quantum Efficiency
Unwanted random variations in shades of grey
◦Prior image cannot be erased
Graphical representation of the signal intensity of pixels
% of the xray energy that strikes the detector/converted to the final image
29
spatial resolution is
the degree of geometric sharpness
accuracy of the structural lines actually recorded in radiographic image
all of the above
definition
30
In indirect conversion, the xray photons are converted to ____ and then into electrical signal.
light
protons
electrons
heat
31
What is a photodetector
Converts light to electrical signal
Converts light to thermal signal
Converts light to mechanical signal
Converts electrical signal to light
32
What is this artifact?
grid cut off
motion
incorrect SID
grid tilt
33
Name the artifact:
Shading
Backscatter
Dirt/debris
IR plate reader
34
The purpose of the photomultiplier tube is
To filter out photons which strike the crystal from oblique angels
To minimize the amount of scattered radiation in the final image
To convert light into an electrical signal and to magnify that signal
To convert radioactivity into light
35
Automatic rescaling means that images are produced, regardless of the amount of exposure, with
variable size and shape.
uniform contrast and density.
variable contrast and density.
uniform size and shape.
36
Photoconductors are materials that
absorb x-rays and produce electrical charges.
produce light when absorbing x-rays.
produce x-rays when absorbing light.
absorb light and produce electric charges.
37
what is byte
A series of steps used to perform an action
A series of steps used to perform an action.
information in a digital computer is represented by 0 and 1s
A set of privileges for allowed actions
38
High-pass filtering is useful for enhancing:
fine bone tissues
small structures
large bony structures.
organs and soft tissue
39
MIMPS= Medical Image Management and Processing System
False
True
40
Most popular type of amorphous silicon detector uses cesium iodide (CsI) scintillator.
False
True
41
Window level controls
Image Contrast
Image Brightness
42
Amorphous silicon?
amorphous selenium
converts light directly to an analog using sensor chip lens or fiberoptics
IDR with TFT technology
the ability to produce light
43
What is another name for gain calibration?
flat fielding
fill factor
accrument
detector incubation
44
DQE?
Measurement that determines how efficient the IP converts photons into data
causes a HALO effect due to high pass filtering
Distance between the centers of two pixels
caused by low pass filtering. Reduces noise
45
CCD/CMOS is :
direct DR
indirect CR
indirect PSP
indirect DR
46
Detective Quantum Efficiency (DQE)
measurement of the percent of x-rays that is absorbed through the IR
all of the above
High DQE produces higher quality images at a lower dose
how efficiently a system converts the x-rays into a useful output image
47
Ideally we would like to have a modulation transfer function value of:
.5
1
.75
2
48
What is spatial resolution?
ability of an imaging system to render different contrasts
The ability of an imaging system to render small objects
portion of the image forming xrays that represent anatomy
ratio of image to object as a function of spatial frequency
49
Quantum mottle or quantum noise is produced by which of the following technical factor settings?
low kilovoltage
high kilovoltage
highmilliampere seconds
low milliampere seconds
50
The Moiré effect can be caused by
using a grid cassette in the bucky
grid w/ frequency similar to the CR laser scanning frequency
grid cassette in the bucky & frequency similar to CR freq.
using a focused grid upside down in the bucky
51
Spatial resolution
amount of detail present in any image
as # of pixels increases, the spatial resolution increases
the smaller the pixels the greater the spatial resolution
ALL
52
purpose of photomultiplier tube is to
increase amount of radiation exiting the pt
decreases the amount of radiation exiting the pt
produce a small multiple of electrons
produce a large multiple of electrons
53
What is a matrix?
Combination of rows or columns
A small, usually square, "picture element"
Number of bits that control the pixel brightness
54
Contrast Resolution =
Dynamic range÷#gray shades
#rows×#columns×#bits per pixel
55
Increasing bit depth ____________ contrast resolution.
increases
decreases
56
Why/how is a plate artifact generated?
Attenuation through different tissues causes scattering
All of the above
Target is too truncated, causing blips on imaging
Memory on the flat panel affects the subsequent imaging
57
Amorphous silicon (a-Si) is a semi-conductor used in
Indirect DR
Direct DR
Ms. Ross made that word up
58
The reader scans the plate in a zigzag or _________ pattern.
raster
wavy
roster
Moire
59
amorphous selenium
phosphorescence
RS 400
photodetector
direct panel photoconductor
60
Window level determines _, and window width determines _.
image density; image color
image density; image contrast
image dense; image controversy
image weight; image contrast
61
Digital radiography using an amorphous selenium layer:
Is part of a two-step process
Is referred to as indirect digital radiography
Converts x-ray photons to lie and then an electrical
Directly converts x-ray photons into an electrical signal
62
Digital radiography using an amorphous selenium layer:
Converts x-ray photons to lie and then an electrical
Is referred to as indirect digital radiography
Is part of a two-step process
Directly converts x-ray photons into an electrical signal
63
Barium fluorohalide with europium is used:
as phosphor that absorbs x-ray energy in flat-panel detector
in the CR reader to remove the image and process it.
in the CR reader to erase the image.
as phosphor that absorbs x-ray energy in the imaging plate.
64
Offset correction is used to remove inherent signal in a detector.
True
False
65
Possible causes of image lag include all but
overexposure
lack of beam attention
underexposure
rapid succession images
66
Histogram is
History of exposure values for the entire hospital
History of exposure values for this exposure ONLY
History of exposure values for this machine
67
Amorphous Selenium is both the capture element and coupling element in direct DR.
True
False
68
What is low-pass filtering?
averaging the frequency of each pixel w/surrounding pixel values
technique for the enhancement of contrast
a reduction in spatial resolution
amplification of the frequencies of the areas of interest
69
The moire effect
that gif is giving me a headache! nExt qUEStIoN!
Happens when the sampling frequence of CR matches with grid frequency
is an artifact that can only happen in Direct Capture Radiography
Yellow
70
Which of these does not cause dead pixels?
chemical corrosion
static discharge
software programs
age
71
The exposure indicator number on the monitor is an indication of radiation absorbed by the imaging plate.
True
False
72
High-pass filtering results in
decreased spatial resolution
increased contrast and edge enhancement
decreased contrast and image blurring
increased patient dose
73
What is the function of the CCD, TFT and CMOS?
converts a digital signal into an analog signal
converts light into an electrical signal
converts an electrical signal into light
converts an analog signal into a digital signal
74
define pixel
picture element
picture equation
picture equivalent
picture elongation
75
Which radiographic imaging process uses a receptor plate and a plate reader?
Digital Radiography (DR)
Computer Tomography (CT)
Computed Radiography (CR)
FIlm
76
Bit depth is
The number of samples per bit
The number of bits per sample
The number of ones and zeroes per bit
The number of measurements per sample
77
Signal to noise ratio
Does not affect echo strength
Is not affected by output power
Compares the meaningful info in an image to the contaminated
Is high when the noise is stronger than the signal
78
Window level
gray-scale
brightness
contrast
density
79
edge enhancement is also known as?
histogram scaling
contrast scaling
spatial frequency
edge enhancement
80
Possible causes of image lag are
rapid succession images
lack of beam attenuation
overexposure
all of the above
81
The capture element of an IR is Amorphous Selenium (a-Se), what type of radiography imaging is referred to?
PSP (CR)
Indirect DR
Direct DR
Conventional S/F
82
What limits contrast resolution?
Spatial resolution
Image noise
Scatter
Image blur
83
Digital radiography using an amorphous selenium layer:
Converts x-ray photons to lie and then an electrical
Is part of a two-step process
Directly converts x-ray photons into an electrical signal
Is referred to as indirect digital radiography
84
Spatial frequency describes the quality of spatial resolution in
pixel size
contrast resolution
MTF
line pairs
85
Dead Pixels = ____ areas where pixels are damaged
Black
White
86
DQE measures what?
time
x-ray absorption effiiciency
distance
noise
87
What is contrast resolution?
ability to distinguish between 2 objects
ability to distinguish many shades of gray from black &white
number of gray shades that an imaging system can reproduce
ability to determine image noise
88
High-Pass Filtering is also called?
Quantization
Edge Enhancement
Smoothing
Equalization
89
Look-up Table?
the incidence that a particular exposure value has occurred.
amount of exposure
Provides contrast adjustment
graphical representation of numerous shades of gray within an image
90
Name the artifact:
Quantum mottle
Double exposure
Backscatter
Aliasing
91
Plate reader artifacts are caused by:
Debris on the mirror
Dirt, dust, scratches on the light guide
Choosing wrong technical factors
Cracks in the plate
92
All Quantum Mottle is Quantum Noise
False
True
93
What is annotation?
aka / shuttering
highlighting area on xray
note of explanation added to an xray
94
In the PSP reader, a laser scans the imaging plate in a:
circular pattern
horizontal pattern
raster pattern
random pattern
95
Gain calibration will remove inherent detector artifacts from an image.
true
false
96
Signal to noise ratio describes
how useful information is
the amount of information provided
how one thing is caused from another
a sample bias
97
Spatial frequency?
What shade of gray? and Where is it?
complex mathematical methods used to created computerized digital images.
Measures image sharpness with units of lp/mm
Enables viewer to see anatomy in areas that are lighter in appearance.
98
Which detector uses amorphous selenium
CR detector
Indirect detector
Direct detector
Film detector
99
edge enhancement:
decreases spatial resolution
decreases image noise
blurs an image
increases visualization of small, high contrast strucures
100
Edge enhancement:
decreases spatial resolution.
blurs an image.
decreases image noise.
increases visualization of small, high contrast structures.
