1
Q
Increased visibility of details is a pros of ___ kVp
A
Variable
2
Q
Decreased patient dose is a pros for ___ kVp
A
Fixed
3
Q
Increased consistent of IR EXPOSURE is a pros of ___ kVp
A
Fixed
4
Q
Small increments change in exposure to compensate for body parts is a pros for ___ kVp
A
Variable
5
Q
Lengthen exposure latitude is a pro for ___ kVp
A
Fixed
6
Q
Increased contrast images is a pros for ___ kVp
A
Variable
7
Q
Increased resolution is a pro for ___ kVp
A
Variable
8
Q
Decreased xray tube wear is a pro for___ kVp
A
Fixed
9
Q
Decreased patient motion & time settings are pros for ___ kVp
A
Fixed
10
Q
Which of the following is/are cons for fixed kVp
A. More scatter
B. Increased image contrast
C. Decreased image contrast
D. Increased tube wear
E. A & B
F. A & C
G. C & D
A
F- more scatter and decreased contrast
11
Q
What are the pros for FIXED kVp (6)
A
- Decreased dose
- More image information
- Increased consistent IR exposure
- Lengthen exposure latitude
- Decreased xray tube wear
- Decreased time setting & pt motion
12
Q
Which of the following are pros for VARIABLE kVp?
A. Decreased contrast
B. Increase contrast
C. Increase resolution
D. Decrease resolution
E. A & D
F. B & C
A
F. - increase contrast & resolution
13
Q
What does a fixed kVp provide?
A
- Uniform contrast
2.easily remembered kV series to add mAs
14
Q
To achieve an appropriate image, what is being kept constant, and what is varied
A
Constant - kVp
Varied - mAs
15
Q
Technique factors function best when ___
A
LARGE # being kept constant while a SINGLE factor is varied
16
Q
What is the goal of exposure systems
A
Provide method of consistency in quality of images
17
Q
Variables of exposure systems changes to ___
A
Thickness of body part
18
Q
What required that the technical factors for each exposure be recorded, regardless of whether the image is within acceptance limits
A
Fine- tuning
19
Q
Variable mAs system depend on ___ (2)
A
IR Exposure & body thickness
20
Q
To establish a variable kVp system, what are the three criteria?
A
- All contrast is acceptable
- Small-part size kVp provide adequate penetration
- Large-part size kVp avoid xs scatter fog
21
Q
Small-part size kVp ____
A. Provide Adequate penetration
B. Avoid excess scatter fog
A
A
22
Q
Large-part size kVp ____
A. Provide Adequate penetration
B. Avoid excess scatter fog
A
B
23
Q
What component within AEC measured exposure to IR?
A
Ionization chamber
24
Q
What does ionization chamber controlled?
A. Contrast
B. IR Exposure
C. Brightness
D. Kvp
A
B
25
What eliminate the radiographer’s need to set mAs
AEC
26
What is direct action
ionizing particles interact directly with macromolecules (DNA) = inactive or functionally altered
27
Is direct or indirect action more common? Why?
Indirect --> water more abundant
Direct --> random 1% chance
28
Effects of direct action
direct energy exchange to DNA = DSB/SSB = apoptosis
29
What is indirect action
radiolysis of water (breakdown of water from radiation)
30
How does indirect action occur
x-ray interacts with water = ionization = breaks apart = free radicals --> secondary radiation
31
What is a free radical
atom with single unpaired electron
32
Characteristic of free radical
Highly reactive
short life span (1millisecond)
causes cell death
33
Ways free radicals causes damage
ionization
excitation
creation of toxic substances --> peroxide and superoxide
34
What is high LET associated with? Is damage repairable?
direct action --> DSB
Repairable? unlikely
35
What is low LET associated with? Is damage repairable?
point mutation
Repairable? yes --> action of repair enzymes
36
What is non-threshold relationship
any radiation dose has the capability of producing a biologic effect
37
What is threshold relationship
below a certain radiation level or dose, no biologic effects are observed
38
Which relationship best fits
"No radiation dose can be considered absolutely safe"
non-threshold
39
List cellular effects of irradiation (7)
instant death
reproductive death
apoptosis
mitotic death
mitotic delay
Permanent or temporary interference with function
Chromosome breakage
40
What causes cellular effects of irradiation
Type of cell reaction from amount of transferred energy to cell's nucleus
41
Instant death
given 1000+Gy/s, disrupts cellular form, structure, and chemistry
42
Reproductive death
given 1-10Gy
43
What does AEC permits?
adjustment of radiation amount to send termination signal
44
Many ionization chambers are activated to control_____
exposure
45
which component of the ionization chamber terminate exposure when appropriate Voltage reached
operation amplifier
46
to establish exposure system, a variety of technical factor combinations are used, but which factor is being kept the same?
a. mAs
b. kVp
mAs
47
___kVp provide uniform contrast and easily remembered kV series to add mAs
a. fixed
b. varied
c. optimal
FIXED
48
What does optimal kVp produce?
lower contrast and minimum patient exposure
49
What is the objective to establish optimal kVp
determine highest kVp and lowest contrast within acceptable limits
50
What should be avoided near chamber location for AEC?
too tight and too wide collimation
51
Why avoid tight collimation near chamber location of AEC
to avoid overexposed image since the chamber will mistake the tissue to be extremely dense
52
Why avoid wide collimation near chamber location of AEC
avoid underexposed image since wide collimation results in scatter radiation, causing AEC to terminate early
53
Which of the following will result in underexposed image?
a. tight collimation
b. wide collimation
c. too short back-up timer
d. too long back-up timer
e. A & B
f. B & C
g. A & D
F - wide collimation & too short timer
54
Which of the following will result in overexposed image?
a. tight collimation
b. wide collimation
A
55
Which AEC component can prevent overexposure
back-up timer
56
How much % is anticipated manual exposure time?
150
57
Because displayed images do not proved any visual cues of overexposure, manufacturers developed:
a. Rescaling
b.Target Exposure
c. Deviation Index
d. Exposure Indicators
Exposure Indicators
58
The Target Exposure Indicator is derived from the:
a. Pixel Value
b. Log of Median
c. Speed Class
d. Look Up Table (LUT)
a. Pixel Value
59
What does exposure indicator represent?
a. LUT
b. speed class
c. IR exposure
C - IR exposure
60
high EI = ____ exposure
low EI = ____ exposure
excess
insufficient
61
Target EI represents _____ at ____ for specific ____
exposure
IR
speed class
62
______ can be used by all manufactures regardless of their specific method for calculating EI
deviation index
63
what is the unit for DI?
microgray
64
microgray unit must be included in ____
dicom header
65
What information must be included in DICOM HEADER for every image
1. DI readout
2. EI delivered (in microgray)
66
What can lead to a corrupted DI and EI
errors in histogram analysis
67
Can a corrupted EI cause corrupted DI readout?
yes
68
Deviation Index is ____
a. direct measurement of patient dose
b. direct indicator of IR dose
c. direct measurement of IR dose
B - direct indicator of IR dose
69
Which of the following can be roughly extrapolated (estimated)?
a. IR dose
b. pt dose
B - pt dose
70
What are the factors that can raise or lower the deviation index (4)
1. poor collimation
2. unusual body habitus
3. presence of prosthetic device
4. presence of gonadal shielding
71
What does speed class express
its sensitivity to radiation exposure
72
what made up of speed class
inherent speed of IR & digital processing speed
73
When is inherent speed important
at the image acquisition state
74
which speed class assume average exposure of 20 microgray?
a. 100
b. 200
c. 400
100
75
which speed class has remnant xray beam exposure at 10 microgray
a. 100
b. 200
c. 400
200
76
which speed class has remnant xray beam exposure at 5 microgray
a. 100
b. 200
c. 400
400
77
What is the speed class manufacture usually set to reduce chance of quantum mottle
a. 100
b. 200
c. 400
200
78
An underexposed image will have a DI ___
a. less than -1
b. more than 1
c. less than 0
A - less than -1
79
An underexposed image should not be repeated unless:
a. radiologist finds unacceptable amount of mottle present
b. saturation present
c. supervising technologist tells u to repeat
d. exposure indicator number indicated underexposed
a. radiologist finds unacceptable amount of mottle present
80
An overexposed image should not be repeated unless:
a. The radiologist finds an unacceptable amount of mottle present
b. When the lead technologist tells you to repeat it
c. When saturation occurs and there is a loss of data
d. The exposure indicator number indicates an overexposure
c. When saturation occurs and there is a loss of data
81
overexposed images can be fixed through ____
windowing
82
how do you tell if an image is over-processed but not saturated
if details can be seen in dark portions of the image
83
an electrical phenomenon that occurs at the detector when the dexels in a particular area have reached the maximum electrical charge that they can store is termed:
a. saturation
b. overexposure
c. underexposure
d. quantum mottle
A - saturation
84
Nearly all DR & CR machines can operated at a speed class of 350-400 without the appearance of ____
a. substantial saturation
b. substantial mottle
c. distortion
d. spatial resolution
B
85
What does saturation represent
complete loss of data
86
Where and when does saturation occur
where - at detector
when - dexels reach maximum electrical charge they can store
87
why further increase in exposure cannot be measured?
all dexels reach max electrical charge AND tissues display as pitch black
88
Is true saturation often occur?
no
89
why true saturation is rare occurence
bc it requires 10 times normal radiographic technique
90
A deviation index of 3.0 would show:
a. 26% overexposure
b. 100% overexposure
c. 63% of target exposure
d. 59% overexposure
100% exposure
91
A deviation index of 1.0 would show:
a. 26% overexposure
b. 100% overexposure
c. 50% of target exposure
d. 59% overexposure
a. 26% overexposure
92
A deviation index of -1 would show:
a. 100% underexposure
b. 50% underexposure
c. 63% underexposure
B - 50% underexposure
93
Which exposure indicators would be repeated if radiologist dictates?
a. +1 to +3
b. greater than 3
c. -1 to -3
d. less than -3
e. -0.5 to + 0.5
c. -1 to -3
94
Which exposure indicators would not need to be repeated unless saturation occur?
a. +1 to +3
b. greater than 3
c. -1 to -3
d. less than -3
e. -0.5 to + 0.5
A & B
95
Which exposure indicators would describe the target range?
a. +1 to +3
b. greater than 3
c. -1 to -3
d. less than -3
e. -0.5 to + 0.5
E -0.5 to + 0.5
96
The image quality of grayscale/contrast is mainly controlled by:
a. Look Up Table (LUT)
b. mAs
c. Rescaling
d. kVp
a. Look Up Table (LUT)
97
The image quality of brightness/ density is mainly controlled by:
a. Look Up Table (LUT)
b. mAs
c. Rescaling
d. kVp
c. Rescaling
98
The image quality of sharpness(Spatial resolution) is mainly controlled by:
a. Look Up Table (LUT)
b. matrix size
c. pixel size
d. kVp
c. pixel size
99
The image quality of magnification is mainly controlled by:
a. Field of View
b. matrix size
c. pixel size
d. part alignment
A & B
100
The image quality of shape distortion is mainly controlled by:
a. part alignment
b. matrix size
c. pixel size
d. kVp
a. part alignment
101
Apoptosis
cell death without dividing → with or without radiation
102
Mitotic death
cell die after 1 or 2 divisions
103
Mitotic delay
given 0.01Gy → cell failed to divide in time
104
Chromosome breakage
loss of genetic material leads to mutation from radiation interacting with DNA
105
What is Skin Erythema Dose (SED)
amount of radiation given caused diffuse redness over an area of skin
106
What was SED used for?
1900-1930 Used to determine radiation exposure but was inaccurate → reaction varied by person
107
What is tolerance dose also known as?
Threshold dose
108
What is tolerance dose
continuous radiation dose in occupational workers without any apparent harmful acute effects
109
What was tolerance dose used for?
Used in 1930 to measure exposure in air (Roentgen)
110
When would a dosimeter be required to be worn?
Receiving 10% or more of annual limit of 5rem (50mSv)
111
Types of dosimeters?
Personnel
Area monitoring
112
Types of personnel dosimeters (4)
Optically stimulated luminescence dosimeters (OSL)
Film badges
Thermoluminescent dosimeters (TLDs)
Pocket ionization chambers
113
Optically stimulated luminescence dosimeters (OSL)
Pro? (5)
Con? (1)
Pro: lightweight, easy to carry, not affected by heat, moisture or pressure
Con: can only monitor area if worn
113
Film badges
Pro? (2)
Con? (1)
Pro: film is legal document of radiation exposure and can differentiate between different types of radiation
Con: heat + moisture can cause fogging over time
114
Thermoluminescent dosimeters (TLDs)
Pro? (4)
Con? (2)
Pro: monitors dose accurately, humidity, pressure and is unaffected by temperature
Con: expensive and can only be read once
115
Pocket ionization chambers
Pro? (4)
Con? (2)
Pro: immediate exposure readings, compact, convenient and easy to carry
Con: most expensive, can give inaccurate readings if not read everyday
116
Which type of personnel dosimeter is the most sensitive?
A. OSL
B. Film badges
C. TLDs
D. Pocket ionization chambers
D. Pocket ionization chambers
117
Which of the following is true of proper dosimeter wear?
A. It is mandatory to wear your dosimeter when working
B. Dosimeters can be worn under a jacket
C. When wearing a lead apron it can be worn under the apron on the collar area
D. Always keep your dosimeter at the workplace and never bring to another institution
D
118
How much radiation exposure should a pregnant technologist recieve?
0.5mSv/month
119
Types of area monitoring detector
Ionization chamber-type survey meter (cutie pie)
proportional counter
geiger-muller detector
120
How does area monitoring instruments work?
responds to radiation interacting with and ionizing gas (air)
121
Pros to radiation survey instruments for area monitoring (5)
portable
durable/reliable
interacts with radiation similar to human tissue
detects all types of radiation
cost effective
122
Law of Bergonie and Tribondeau
Radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation
123
The more a cell reproduces/divides the more _______
Radiosensitive the cell is
124
What type of somatic effect is an acute radiation syndrome
early deterministic somatic effect
125
How does acute radiation syndrome occur
when given large doses of radiation in a short period of time
126
4 stages of acute radiation syndrome in order
Prodromal → latent → manifest illness → recovery or death
127
Syndromes that contribute to acute radiation syndrome
hematopoietic
gastrointestinal
cerebrovascular
128
Stochastic effect
probability that the effect happens depends on received dose but severity of effect does not
129
Deterministic effect
both probability and severity are dependent on dose
130
Examples of stochastic and deterministic
stochastic: carcinogenesis and embryologic effects (birth defects)
deterministic: cataractogenesis
131
AAPM position on gonadal and fetal shielding
Support ending shielding specifically during abdominal and pelvic radiography because it can increase repeat exposure risk
132
Pros of a fixed kVp chart (6)
decrease patient dose
gives more image information
increase consistency of IR exposure
lengthens exposure latitude
reduces xray tube wear
decrease time settings/patient motion
133
Cons of a fixed kVp chart (2)
more scatter
lower contrast
134
Pros of variable kVp system (5)
allows small changes in exposure to compensate for body part thickness variations
finer adjustments settings than mAs
higher contrast image
enhances visibility fine details
increases resolution
135
what is AEC and what does it stand for?
Uses ionization chambers to measure exposure to IR
Automatic exposure controls
136
Pros of AEC (2)
Eliminating need to set exposure time (mAs)
mA and kVp can still be set manually
137
What is the structure of LCD monitor
front glass --> polarizing film --> color filter --> liquid crystal --> polarizing film --> back light
138
What is the material of the thin layer liquid crystal
hydrogenated amorphous silicon
139
What does the polarizing glass include to conduct electricity?
flat wires
140
Which workstation has higher-resolution monitor?
a. display
b. diagnostic
b. diagnostic
141
Which workstation can save changes into picture archive & PACs?
a. display
b. diagnostic
a. display
142
What can pass through polarizing lens?
light waves with electrical component parallel to molecular chains
143
What cannot pass through polarizing lens? Why?
Xray because its electrical component is perpendicular to its magnetic component
144
What orientation of polarizing lens will block all light from passing through?
a. 2 lens parallel
b. 2 lens perpendicular
B
145
What is the arrangement used to construct LCD monitor screen?
a. iodine chain molecules perpendicular to each other
b. iodine chain molecules parallel to each other
A
146
Which component is in between 2 polarizing lens?
a. front glass
b. liquid crystal
c. backlight
b. liquid crystal
147
What does the imaging monitor must have?
fast response and refresh time
148
Which of the characteristic of imaging monitor change brightness?
a. fast response
b. fast refresh time
A
149
Which of the characteristic of imaging monitor reconstruct next frame of a dynamic image?
a. fast response
b. fast refresh time
B
150
To achieve fast response and refresh time, what is required?
Active Matrix LCD (AMLCD)
151
What is the benefit of AMLCD?
read entire row of pixels at one time rather than a single pixel at a time
152
What does each hardware pixel possess
Thin Film Transistor (TFT)
153
What is the refresh rate of AMLCD?
a. 150 Hz (cycles per s)
b. 200 Hz (cycles per s)
c. 240 Hz (cycles per s)
d. 500 Hz (cycles per s)
C
154
What are the 3 problems of AMLCD?
input lag, dead pixels, dark spots
155
What caused input lag?
a. too much processing
b. electrical charge cant be applied across pixel
c. stucked pixels that receive constant electrical charge
A
156
What caused dead pixels?
a. too much processing
b. electrical charge cant be applied across pixel
c. stucked pixels that receive constant electrical charge
B
157
What caused dark spots ?
a. too much processing
b. electrical charge cant be applied across pixel
c. stucked pixels that receive constant electrical charge
C
158
which of the following problems of AMLCD will result in appearance of permanent white dots?
a. input lag
b. dead pixels
c. dark spots
B
159
If electrical charge cannot be applied across pixel, what is the result?
dead pixels - white spots
160
If electrical charge constantly applied across pixels, what is the result
dark spots
161
too much rescaling, noise reduction, and edge enhancement result in :
a. input lag
b. dead pixels
c. dark spots
A
162
Which of the following will require the monitor to be replaced?
a. less than 15 defective pixels
b. more than 3 defective pixels in any 1cm circumference
c. more than 2 defective pixels in any 1cm circumference
d. more than 10 defective pixels
B
163
if there are more than 15 defective pixels, will the monitor need to be replaced?
YES
164
If there are less than 3 defective pixels next to each other, will the monitor need to be replaced?
NO - Replace if more than 3
165
What does LCD monitor replace?
cathode-ray tube monitor & viewbox
166
4 pros of LCD monitor that improve image quality
1. no distortion or change in sharpness
2. no glare & minimal reflection of ambient light
3. no flicker
4. uniform & consistent brightness
167
4 cons of LCD monitor
1. pixelation
2. substantial limited contrast to 600:1
3. sensitive to change in temperature
4. viewing angle dependence
168
what does the radiologist frequently do if contrast is limited
windowing
169
How long does it take to warm up the monitor to reach full luminance
15minutes
170
Increased angle of observer = ____ brightness of monitor
decreased
171
Which of the following is the monitor sensitive to:
a. radiologist
b. temperature
c. kVp
d. brightness
B
172
Which components determine the sharpness of image?
pixel and dexel size
173
what does pixel size used for
process image
174
what does dexel size used for
record latent image
175
what determine monitor's inherent resolution capability
a. hardware pixel
b. hardware dexel
a
176
decreased in hardware pixel size = _____ sharpness
increased
177
increased sharpness = _____ inherent spatial resolution
increased
178
Which pixel size will give high resolution image?
a. 1-2mm
b. 0.1-0.2mm
c. 0.5 - 1mm
d. 0.01 - 0.002 mm
B
179
a pixel size of 0.1-0.2mm = _____ spatial resolution
increased
180
dot pitch aka ____
pixel pitch
181
what is pixel pitch
distance bw 2 centers of any 2 adjacent hardware pixels
182
smaller pixel pitch = ____ sharpness
sharper
183
smaller pixel pitch = _____ pixel size
smaller
184
___ focal spot = more blur than display monitor
large
185
distal extremities should be done on _____ focal spot
small
186
using a large focal spot on distal extremities will ____
more blurry images
187
soft pixel display ___ image
light
188
soft pixels can be changed by _____
zooming FOV in or out
189
What is luminance
rate of light/brightness emitted from a source (LCD monitor)
190
which of the following gives a standardized area to measure and compare brightness?
a. luminance
b. illuminance
c. contrast
A
191
which of the following describe rate of light emitted in all directions
a. lux
b. lumen
c. candela
C
192
Which of the following is a measure of illluminance
a. lux
b. lumen
c. candela
A
193
which of the following refers to brightness of light within one single steradian
a. lux
b. lumen
c. candela
B
194
luminous flux = _____
a. lumens
b. candela
A
195
luminous intensity = ____
a. lumens
b. candela
B
196
1Cd = 1 __
a. lux
b. lumen
B
197
What is the minimum brightness capability for display system?
a. 200 Lm
b. 250 Lm
c. 300 Lm
d. 400 Lm
B
198
Photometer use which of the following effect
a. compton scattering
b. photoelectric effect
B
199
How much Lm radiologists typically prefer?
500-600Lm
200
What is illuminance
rate of light striking a surface measured in lux
201
for accurate diagnosis, ambient light should not exceed ___
a. 25 Lm
b. 25 Lux
c. 30 Lm
d. 30 Lux
B
202
1-quarter of normal office light = ____ lux
25
203
What is DICOM
digital imaging and communication in medicine
204
Who developed DICOM
ACR
205
What is PACS
picture archiving and communication system
206
DICOM is the groundwork for ___
PACs
207
What is archiving
permanent location for digital images arranged by computers & storage space
208
Which method keeps a complete copy of archive in another location that is immediately available in the event that the front-line archive goes down
a. disaster recovery
b. long-term storage
A
209
Hospitals use ____ for long-term storage
a. application service provider
b. application service user
A
210
What does PACs consist of (3)
digital acquisition
display workstation
storage devices
211
An electronic version of the radiologist reading room and file room is ____
a. PACs
b. DICOM
A
212
Which is the most interactive part of PACs?
a. display workstation
b. digital acquisition
A
213
What are the 3 common PACs
1. client/server based system
2. distributed systems
3. web-based systems
214
What do you do for monthly quality assurance testing? (4)
erase all plates
acquire QC phantom image
implement QC measurement
monitor calibration for QC workstations
215
What are the 3 steps for monitoring calibration for QC workstation
1. check spatial resolution
2. grayscale and brightness
3. SMPTE pattern
216
Types of CR artifacts (6)
white specks/traces
vertical band artifact
visible plastic support
moire or aliasing
latent imaging --> double exposure/ghosting
incorrect image processing
217
Types of DR artifacts (4)
pixel defects
ghosting
moire or aliasing
incorrect image processing
218
how to correct white speck/traces
clean dust or hair off plates
219
how to correct vertical band artifact
Foreign material on light collection guide
220
how to correct visible plastic support
imaging plate and cassette upside down in cassette holder
221
how to correct moire/aliasing in CR
grid scan frequency mismatched
222
how to correct latent image
erase detector
short erase time or dim/burnt out bulb
223
how to correct incorrect image processing CR
incorrect positioning/ wrong body view selected
histogram,LUT, or rescaling error
224
how to correct pixel defects
cannot the inherent detector is defective
225
how to correct ghosting in DR
memory effect
electrical charge is trapped
Raad 354 - Physics
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