1
Q
Unit for effective dose
A
Sv & REM
2
Q
Unit for absorbed dose
A
Gy & RAD
3
Q
Becquerel is a unit of
A
radioactivity
4
Q
Coulombs/kg is a unit of
A
exposure
5
Q
equation for inverse square law
A
I1/I2 = (D2)^2/ (D1)^2
6
Q
equation for grid ratio
A
h/d
7
Q
equation for GCF (nongrid –> grid)
A
mAs (grid)/ mAs (w.o grid)
8
Q
Higher grid ratio means ___ (2)
A
better scatter clean up
better contrast
9
Q
equation for GCF (grid –> another)
A
mAs1/mAs2 = GCF1/GCF2
10
Q
equation for wavelength
A
w = c/f
11
Q
equation for frequency
A
f = c/ w
12
Q
ionization radiation = ___ wavelength = _____ frequency
A
short, high
13
Q
unit for frequency
A
hertz (Hz)
14
Q
rank longest to shortest wavelength
A
radiowave
microwave
infrared light
visible light
UV light
xray
gamma rays
cosmic rays
15
Q
5 characteristics of Xray
A
- highly penetrating (short wave, high frequency)
- cannot be reflected or focused
- neutrally charge
- no mass
- travels in straight line
16
Q
high penetrating, low ionization is ___
A
gamma
17
Q
low penetrating, high ionization
A
alpha
18
Q
which radiation produced at the anode
A
primary
19
Q
beams with different energy is called ___ (aka ___ radition)
A
heterogenous - primary
20
Q
What are considered primary radiation
A
Brems & characteristics
21
Q
Brems produced ____ xray spectrum
A
continuous
22
Q
Characteristics produced ___ xray spectrum
A
discrete
23
Q
primary beam photons have keV energy of ___
A
30-40% kVp
24
Q
What are considered secondary radiation
A
scatter & leakage
25
what is produced by the energy of primary beam redirected after interacting with matter
scatter
26
scatter radiation does not produce __
quantum mottle
27
scatter radiation effect on images (3)
produce noise
reduce contrast resolution
makes image less visible
28
how do we reduce scatter (4)
1. decrease volume of tissue
2. decrease kVp
3. increase collimation
4. increase atomic #
29
decrease kVp = ___ scatter
reduce
30
increase atomic # = ___ scatter
decrease
31
what devices are used to reduce scatter (3)
collimator
beam-restring devices
grid
32
which beam-restring devices is the simplest? and which is the most effective in scatter cleanup
simplest: aperture diaphragm
effective: cone
33
which of the following is not beam-restricting devices:
a. aperture diaphragm
b. grid
c. collimator
d. cones
e. all of the above are beam-restring devices
B
34
what is the purpose of grid
reduce scatter radiation that reached IR
35
what is beam restrictors and grid have in common
reduce scatter
36
reduction in total # of xray photons remaining in beam after passing thru given thickness of material is ___
a. HVL
b. attenuation
B
37
thickness of absorbing material required to reduce x-ray intensity to half of its original value is ___
a. HVL
B. attenuation
A
38
what does HVL measures?
a. quantity
b. quality
A
39
2 ways to remove low-energy photons
filteration
hardening of beam
40
remove low-energy photons = ___ patient dose
decrease
41
High-voltage generator is ___ circuit
secondary
42
Components of primary circuit (5)
1. power supply
2. autotransformer
3. kVp meter
4. timer
5. step-up transformer
43
what controlled autotransformer?
a. kVp selector
b. mA adjusment
A
44
What operate autotransformer
self-induction
45
what component of the circuit directly determine V
autotransformer
46
AEC timer utilized ____ for exposure control
ionization chamber
47
cons of AEC backup timer
too short = underexposed image
48
AEC measures ___ of radiation reached IR
a. quantity
b. quality
A
49
mA selector controls ___ in the circuit
amperage
50
Rectifiers are located in ___ circuit
secondary
51
which component transform AC to DC
rectifiers
52
Rectifiers is ___ diode
solid state semiconductor
53
half wave have ____ diodies
full wave have __ diodes
0,1,2
4
54
ionization chamber is radio___
radiolucent
55
what does rectifier require to operate
voltage rectification
56
what does high-voltage transformer require to operate
AC
57
Which component increase voltage from autotransformer by a fixed amount
step-up transformer
58
what does filament circuit control
degree & saturation the filaments are heated
59
what activate step-down transformer
a. kVp seelctor
b. mA adjustment
B
60
3 parts of high-voltage generators
step-up transformer
filament transformer
rectifiers
61
increase amperage = increase in __
# of e- boiled off
62
the filaments are at which side of the tube
cathode
63
Tube housing can reduce ____
leakage radiation
64
Tube housing can prevent ___
electric shock
65
what is used in the tube housing as an insulator & thermal cushion
OIL
66
why glass is used for tube envelope
withstand heat
67
tube window for useful beam to exit is located in ___
glass envelope
68
TUbe current related to ___
mAs
69
what components are on the cathode side?
filament coil
focusing cup
70
function of filament coil
emits electrons when heated
71
function of focusing cup
confines electron beam to a small area of anode
72
what components are on the anode side
target
rotor
stator
73
functions of anode (3)
1. electrical conductor
2. mechanical support for target
3. thermal dissipater
74
Xray emission source is at __
a. effective focal spot
b. actual focal spot
B
75
why tungsten is chosen as material for target (3)
1. high atomic #
2. high thermal conductivity
3. high melting point
76
____ effective focal spot
____ actual focal spot
small
large
77
a sharper image will have ___ focal spot
small effective
78
pros & cons of small effective focal spot
pros: better spatial resolution
cons: more heat concentration
79
xray emission source is at ___
actual focal spot
80
xray are produced at ___
actual focal spot
81
Bremsstrahlung radiation interacts with
The nuclear field
82
Characteristic radiation interacts with
inner shell electrons
83
Characteristic radiation produced at ___ kVp
above 70
84
The xray primary beam most often consists of
Brems radiation
85
The energy of the beam can be changed through adjustments in
a. kvp
b. mas
c. quantity
d. distance
kVp
86
Off-foused radiation happend at the ___
anode
87
Target is on ___ side
anode
88
off focused radiation produced
ghosting effect
89
what helps reduce the amount of off-focused radiation
upper shutter of collimator
90
rotor is made up of ___
copper shaft & soft iron
91
stator consists of ___
electromagnet
92
Incident e- in photoelectric interacts with
inner shell e-
93
incident e- in compton interacts with
outer shell e-
94
what are ejected from photoelectric
photoelectron
95
what are ejected from compton
electron with ionizing capability
96
what happened when xray strike matter
1. absorbed (photoelectrically)
2. scatter
3. direct transmission
97
reduction in intensity results from ____
absorption & scattering
98
increase kVp = __ PE = ___ Compton
decrease / increase
99
decreased patient dose = ___ PE = ___ Compton
decrease/ increase
100
Which of the following is not required for xray production
a. accelerating of e-
b. slowing of e-
c. rotating target
d. source of free e-
c. rotating target
101
Compton scatter most likely occurs with
a. An xray interacting with an outer shell electron
b. projectile electron interacting with outer shell e-
A
102
The anode heel effect causes
a. An x ray field with lower intensity on the anode side
b. xray with lower contrast
c. xray with higher quality on anode side
An x ray field with lower intensity on the anode side
103
thicker body part is placed on which side of xray tube
cathode
104
increase anode heel effect = ____ angle
small
105
increased anode heel effect = ___ SID
decreased
106
The line focus principle explains the relationship between:____
a. The actual focal spot and the effective focal spot
b. The large focal spot and small focal spot
c. The large focal spot and actual focal spot
A. The actual focal spot and the effective focal spot
107
Line focus principle results in greater ____ & ____
heat capacity
image sharpness
108
For line focus principle, what needed to be angled for heating while maintaining small focal spot
TARGET
109
Quantity aka ____ (3)
xray output
intensity
exposure
110
quantity is affected by ____ (4)
kvp
mas
distance
filtration
111
quantity is measured by _____
milliroentgens
112
Quantity is also known as all of the following except :____
a. xray output
b. exposure
c. energy
d. intensity
C
113
IR exposure is measured by ___
numeric exposure value
114
Quality aka ___
penetrability
115
HIGH penetration in material of ____ atomic #
LOW
116
quality is affected by ____ (2)
kvp
filtration
117
increase mAs = ____ quantity
increase
118
increase kVp = ____ quantity
increased 4x
119
increase distance = ___ quantity
decrease
120
increase filtration = ____ quantity
decrease
121
intensity is _____
a. quantity
b. quality
A
122
increase kVp = ____ speed + energy of photons
increase
123
what can remove low-energy photons
increase filtration
124
increase filtration = ___ resolution
increase
125
Beam quality is a measurement of
a. Half-value layer
b. beam divergence
c. amount of radioactivity
d. amount of xray in primary beam
A
126
What are the prime factors
kvp
mas
distance
127
what material is used for filtration
aluminum
128
thicker filters = ___ atomic # = ____ reduction of output
high
high
129
purpose of filtration
remove low-energy xray photons
130
filtration ____ intensity of beam AND ____ photon energy
decrease
increase
131
total filtration is combination of ____
a. inherent & added
b. inherent & compensating
c. added & compensating
A
132
purpose of grid
improve contrast by absorbing scatter
133
when to use grid
body thickness over 13cm or 10 for film
kvp > 70
134
grid is made up of ____ strips & ____ interspace
radiopaque
radiolucent
135
Grid lines could be visible in all of the following except ___
a. when using stationary grid
b. when the bucky oscillates
c. when CR is not perpendicular to IR
B
136
which type of grid has the tube angled with length of grid without cut-off
parallel
137
which type of grid has focal range
focused
138
grid with wide focal range = ____
low grid ratio
139
better scatter cleanup = ____ grid raatio
high
140
narrow focal range = ____ grid ratio
high
141
which type of grid has 2 linear grids perpendicular to one another
crosshatch
142
which type of grid is best at scatter cleanup
crosshatch
143
if primary beam is angled into lead and leads to decrease in density along periphery of film, what error occured?
grid cut-off
144
how to fix off-level grid
grid perpendicular to CR
145
when does off-focused error occur
when used at SID out of focal rang
146
which type of error is describes:
" focused grid not aligned with labeled tube side facing ray tube"
upside down
147
what is the effect caused by upside-down grid error
uneven exposure
148
What caused moire effect
grid lines captured & parallel to scan lines
149
moire effects occured in ____ grid
stationary
150
HVL is a measurement of beam ____
a. quantity
b. quality
A
151
5 image characteristics
brightness
contrast
noise
distortion
spatial resolution
152
brightness is measured by ____
candela
153
brightness is controlled by ____
a. postprocessing
b. preprocessing
a
154
window level adjusts ___
a. brightness
b. contrast
A
155
increase window level = ___ brightness
decrease
156
why we dont adjust window width for brightness
data from original histogram is lost
narrow dynamic range --> misdiagnosed
157
contrast is ____ of pixel
bit depth
158
contrast describes:
a. visibility
b. sharpness
A
159
distortion describes:
a. visibility
b. sharpness
B
160
brightness & contrast corresponds to :
a. visibility
b. sharpness
A
161
distortion & spatial resolution corresponds to :
a. visibility
b. sharpness
B
162
sharpness is determined by ____ (3)
matrix size
pixel size
bit depth
163
sharpness is measured by ___ (4)
PSF
LSF
MTF
system noise
164
increased kVP = ___ scale
short
165
decreased kVp = ____ scale
long
166
short scale is for which structure
skin
bone
167
long scale is for which structure
soft tissue
168
Window width adjusts ____
a. brighness
b. contrast
B
169
What is the amount of mAs that can compensate for kVp
NONE
170
subject contrast depends on ____
kvp & irradiated material
171
subjected contrast resulted from ____
differential absorption
172
increased subject contrast = ___ kVp
decrease
173
spatial resolution aka ____ (3)
definition, sharpness, recorded detail
174
short wavelength = __ frequeny & resolution
increase
175
short wavelength is for ___ objecct
small
176
problems with spatial resolution (4)
no motion
decreased OID
decreased focal spot size
increase SID
177
if SNR increased = ____ image quality
increased
178
how do you optimize SNR
noise intolerance
set exposure value
monitor
179
noise intolerance = ____
exposure creep
180
lack of attention to wide dynamic range = ____
dose creep
181
decreased noise will ___
increase pt dose
182
difference bw optimal image and best image
optimal: balance of noise & pt dose
best: no noise & high pt dose
183
what caused size distortion
magnification
184
decreased magnification = ___ spatial resolution
increase
185
increase visualization = increased in ___ while maintaining____
OID
SID
186
minimize OID = ____ distortion
decrease
187
maximize SID = ____ distortion
increase
188
why shape distortion happen
object plane & image plane not parallel
189
shape distortion depends on what factors (3)
thickness
position
shape
190
how to decrease shape distortion
body // IR and perpendicular to CR
minimize OID
191
elongation is a type of ___ distortion
shape
192
elongation is caused by ____
a. tube angle
b. body part
tube angle
193
foreshortening is a type of ___ distortion
shape
194
foreshortening is cause by ____
a. tube angle
b. body part
body apart
195
Attenuation varies depend on ____ (2)
pt thickness & composition
196
differential absorption & attenuation depend on ____ (3)
1. atomic #
2. mass density
3. xray energy
197
increase atomic # = ____ attenuation
increase
198
pathology will cause changes in _____ (3)
thickness
effective atmoic #
density
199
Additive is a condition in which ___
there is an increase in thickness, effective atmoic #, and/or density
200
additive conditions ____ attenuation
increase
201
as additive disease worsens, IR exposure ____
decreases
202
Destructive is a condition in which ____
there is an decrease in thickness, effective atmoic #, and/or density
203
destructive conditions ____ attenuation
decrease
204
as destructive disease worsens, IR exposure ____
increase
205
Which of these pathologies result in the increased attenuation of the beam
a. osteoporosis
b. emphysema
c. pneumothorax
d. congestive heart failure
D
206
Which of these pathologies result in the decreased attenuation of the beam
a. tuberculosis
b. pneumonia
c. cardiomegaly
d. emphysema
D
207
tuberculosis
additive
208
pneumothorax
destructive
209
atelectasis
additive
210
pagets disease
additive
211
emphysema
destructive
212
bowel obstruction
destructive
213
osteoporosis
destructive
214
What is being described:
highest actual atomic #
low effective #
low density
AIR
215
What is being described:
lowest effective #
low density
similar tissue to water
FAT
216
What is being described:
high actual atomic #
high effective #
higher density than FAT
MUSCLE
217
highest attenuator is ___
BONE
218
fat has tissue similar to ___
water
219
which one has higher density
a. muscle
b. fat
A
220
How can a technologist tell if an image is overexposed
a. the exposure indicator number will be out of range
b. loss of contrast
c. image show quantum mottle
d. image show saturation
A
221
what is dexel
Rounds average attenuation coefficient to nearest preset value in dynamic range
222
3 components of dexel
A-Se
TFT
Capacitor
223
A pixel corresponds to ___
area of pt's tissue
224
pixel size depends on ____
matrix size
225
___ pixel size = more details
small
226
what is subset of bit depth
dynamic range
227
what is subset of dynamic range
grayscale
228
how to calculate # shade of grays
2^bit depth
229
large matrix size = ____ quality
high
230
voxel is collected by ___
dexel
231
The main image capture component of all dr detectors is the
a. Active matrix array
b. pixel
c. voxel
d. flat panel IR
A
232
AMA is main image capture of ____
a. DR
B. CR
DR
233
What made up of AMA (2)
flat panel & dexel
234
function of AMA
convert remnant xray to electrical signal
235
A cassette-based is used in ___
a. CR
b. DR
CR
236
IR type for DR & CR
DR: TFT
CR: PSP
237
function of PSP
stores xray energy as latent image
238
PSP is sensitive to ___
BG radiation
239
CR imaging plates use which of the following?
a. barium fluorohalide
b. amorphous silicon
c. amorphous selenium
d. barium sulfate
A
240
dexel material for direct capture
amorphous selenium
241
dexel material for indirect capture
amorphous silicon
242
xray strikes the scintillator in ___
a. direct capture
b. indirect capture
c. CR
B
243
which IR type has 7 layers
a. PSP
b. TFT
PSP
244
what is quantization
3rd step of digitizing images
level out brightness level for pixel to nearest gray available in preset dynamic range
245
Histogram shows ___
a. brightness value
b. grayscale.
brightness value
246
histogram has ____ that can recognize false densitities
light field recognition
247
Histogram analysis do 2 things: _____
compare histograms
eliminate data that skew with rescaling
248
5 histograms selection errors
▫Segmentation
▫Matching
▫Prosthetic & lead apron in collimated area
▫Pre-fogging of IR from BG radiation
▫Extreme scatter radiation
249
An image with appropriate spatial resolution could be said to have:___
a. sharpness
b. visibility
c. distortion
d. noise
e. quantum mottle
a. sharpness
250
The total number of pixel values that can be produced by the digital system is the ____
a. bit depth
b. dexel
c. exposure latitude
d. dynamic range
a. bit depth
251
The range of exposures that can be captured by a detector is the ____
a. dynamic range
b. grayscale
c. contrast
d. window level
a. dynamic range
252
The ability to produced quality images within a range of acceptable techniques is _____
a. exposure latitude
b. dynamic range
c. rescaling
d. DQE
a. exposure latitude
253
A graphic representation of the recorded signals received by the IR is known as
a. DR
b. histogram
c. rescaling
d. image sampling
Histogram
254
Spatial resolution is controlled by ___
a. bit size
b. mas
c. kvp
d. pixel size
a. bit size
255
Interpolation can fix ___
a. dead pixels
b. image ghosting
c. effects of scatter
d. segmentation errors
a. dead pixels
256
LUT gives _____
just right amount of brightness & contrast
257
adjustments to LUT
output pixels adjusted to same output Q values
258
LUT adjustments happened during____
image rescaling
259
4 steps to preprocessing?
1. Field uniformity
2. Dexel & noise correction
3.Histogram & analysis
4.Rescaling
260
field uniformity has this computer software called ____ that compensate areas out of range of uniformity
electronic amplification
261
Anode heel effect is partially compensated by ____
field uniformity
262
purpose of field uniformity
correct uneven distribution of BG density
263
What is segmentation failure
When individual exposure cant be separated
264
when will segmentation failure happen
CR
265
interpolation is ___
a. postprocessing
b. preprocessing
B
266
how does interpolation reduce noise
through software KERNEL
267
purpose of interpolation
give dead pixels the gray surrounding it
268
DQE stands for ___
detective quantum efficiency
269
purpose of DQE
measure the efficiency of IR in converting xray into radiographic image
270
DQE =1 means ___
100% of information is converted
271
increase DQE = ___ IR exposure AND ____
decrease
pt dose
272
which of the following provide ideal brightness & balanced grayscale regardless of technique
a. rescaling
b. field uniformity
c. LUT adjustment
RESCALING
273
process of rescaling
S --> Q --> placed in permanent LUT
274
amorphous selenium absorbs _____
a. xray
b. light
a. xray
275
amorphous silicon absorbs _____
a. xray
b. light
b. light
276
which phosphor is in scintillator layer for indirect capture
cesium iodide
277
what is the phosphorescent screen of indirect capture DR
scintillation layer
278
immediate light emission by some types of stimulation is ____
Fluorescence
279
delayed emission of light is ____
Phosphorescence
280
what is the second stimulation to phosphorescence
laser beam
281
latent image becomes ___ after exposure
manifest image
282
underexposure cause ____
quantum mottle
283
overexposure caused ____
saturation
284
windowing affects ___ of images
visibility
285
3 functions of PSP
1. Ionize phosphors
2. Trap e- & convert to electric signals
3. Stores xray energy as latent image
286
exposure latitude controls ____
brightness & contrast
287
wide exposure latitude = ____
low contrast
288
narrow exposure latitude = ____
high contrast
289
what is exposure indicator number
indicate level of radiation exposure to IR
290
if out of exposure indicator range it will cause ____
NOISE
291
what is dynamic range
range of exposure intensities to IR
292
what is dynamic range compression
remove darkest to lightest pixel values from grayscale
293
DRC allows __
windowing
294
spatial domain operation is __
a. preprocessing
b. postprocessing
POSTPROCESSING
295
what is point processing
performs specific pixels in sequence
296
image substraction is an example of ___
a. point processing
b. area processing
c. global operations
A
297
what is area processing
Execute mathematical function on a subsection of image
298
magnification is an example of ___.
a. point processing
b. area processing
c. global operations
b. area processing
299
image orientation is an example of ____
a. point processing
b. area processing
c. global operations
c. global operations
300
with global operations, middle column is being ____ while corresponding columns are ____
translated
inverted
301
detail processing is in which domain operation
frequency
302
windowing is in which domain operation
intensity
303
high frequency = ____ pixel size
increase
304
high wavelength = ____ pixel size
decrease
305
what is submatrix
spatial detail processing with kernels
306
what allows frequency processing to separate structure
fourier transformation
307
4 postprocessing features of detail processing
1. smoothing
2. BG suppression
3. local contrast of fine details
4. edge enhancement
308
mid-size structures suppressed by contrast reduction & move into BG happened in ____
detail processing
309
pro and con of edge enhancement
Pro: increase local contrast for small pathology changes
Cons: increase image noise
310
if over enhance local contrast = ___
loss of details
311
BG suppression reduce contrast of ____ structures
larger mid-frequency and low-frequency
312
pro & con of BG suppression
Pros: effective in tissues like fat pads
Cons: Result is similar to edge enhancement
313
Smoothing removes ___ structures
highest-frequency
314
which 2 postprocessing features give the same result
BG suppression & edge enhancement
315
soft edge is due to ___
decrease in local contrast
316
noise is reduced by ___
interpolation
317
purpose of smoothing
corrects for dead pixels in IR + amount of mottle
318
severe mottle = ___
gross underexposure
319
Cons of smoothing
lose small details that contribute to diagnostic information
320
decoupling local contrast is ____
fine details visible
whole image has same contrast
321
if we eliminate noise, we need to accept the fact that
some fine details are gonna be lost
322
soft tissue technique can be stimulated by ___
DRC
323
adjust pixel values to fit average histogram & small exposure error is _____
rescaling
324
segmentation doesnt occur in ___
a. CR
b. DR
B.
325
what can correct quantum mottle
a. kernel
b. frequency filtering algorithm
c. none
kernel
326
what can correct electric mottle
a. kernel
b. frequency filtering algorithm
c. none
frequency filtering algorithm
327
What is imaging cycle in order
exposure –> histogram –> permanent LUT (rescaling) –> anatomical LUT (gradation) –> default detail processing –> displayed image
rad 350 - Physics
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