Semester 2 physics exams Flashcards
1
Q
If an x-ray imaging system is operated at 600 MA, 100 MS, the total MAS will be?
A
60mAs
2
Q
Electron emission from a heated source
A
Thermionic emission
3
Q
A radiographic technique calls for 800 MA, 1/20 s exposure what is the mAs
A
40
4
Q
The difference between x-rays and gamma rays is
A
Their origin
5
Q
Three main parts of the x-ray imaging system are the x-ray tube, _______, and ______
A
Operating console high-voltage generator
6
Q
When considering the electromagnetic spectrum photons of a radio broadcast have relatively
A
Low energy and long wavelengths
7
Q
Regarding the induction motor on the x-ray tube the only part to rotate is the
A
Rotor
8
Q
Radio waves, light, and x-rays are all examples of ______ energy
A
Electromagnetic
9
Q
Convert AC to DC
A
Rectifier
10
Q
A diode allows electrons to flow _____
A
From cathode to anode
11
Q
Which of the following principles of rectification produces the maximum efficiency of x-ray production
A
High frequency
12
Q
As compared with particulate radiation, electromagnetic radiation Is
A
More penetrating
13
Q
In modern imaging systems the components for rectification are
A
Solid state semi conductors
14
Q
According to quantum mechanics the energy of an x-ray is
A
Inversely proportional to its wavelength
15
Q
When a step up transformer is in use
A
The secondary voltage is greater than the primary voltage
16
Q
The development of modern quantum mechanics is attributed to
A
Max Planck
17
Q
Which of the following has a constant value for all electromagnetic radiation
A
Velocity
18
Q
The mAs timer is usually set to give the ______ mA at the _____ time
A
Highest, shortest
19
Q
Voltage across the x-ray tube is most constant with
A
High frequency generator’s
20
Q
In AEC device can
A
Use an ionization chamber between the patient and the image receptor
21
Q
The high-voltage generator contains a high-voltage transformer and the
A
Rectifiers
22
Q
The difference in the waveform between the primary and secondary sides of the high-voltage transformer is the
A
Amplitude
23
Q
When compared with visible light x-rays have shorter
A
Wavelength
24
Q
Voltage across the x-ray tube is most constant with
A
High frequency generator’s
25
X-ray tube current is usually measured in which of the following
Amperes
26
Smallest quantity of any type of electromagnetic radiation is a
Photon
27
The four properties of photons are
Frequency, wavelength, velocity, amplitude
28
The principal purpose of the high-voltage transformer is to do which of the following
Increase voltage
29
Line compensation is
Required to stabilize voltage
30
X-ray transformers operate on the principle of
Mutual induction
31
The x-ray generator with the lowest power rating is the ______ imaging system
Single phase
32
Variations in power distribution do the x-ray machine Are corrected by The
Line voltage compensator
33
For any electromagnetic radiation and increase in frequency result in
An increase in energy
34
X-rays and gamma rays are both examples of electromagnetic radiation in addition they both have
No electrostatic charge
35
X-rays have ____ mass and _____ charge
No mass no charge
36
The most accurate type of timer is the
Electronic timer
37
A transformer operates on
AC NOT DC
38
What is the removal of an electron from an Atom called
Ionization
39
A single-phase waveform has a ______ ripple
100%
40
If an automatic exposure control device ____ is required
Back up timer
41
The energy of an x-ray photon is directly proportional to its
Frequency
42
Bone that absorbs x-radiation is called
Radiopaque
43
The inverse square law states that
Intensity is inversely proportional to the square of the distance
44
The auto transformer has _____ windings
1
45
The exposure timer on a three phase radiographic imaging system will
Be electronic
46
Which of the following is greater for a 30 KEV x-ray then a 60 KEV x-ray
Wavelength
47
In radiographs of bony structures in bedded in soft tissue the bone is
Radiopaque
48
The inverse square law involving distance could be applied to
All of the above
49
The automatic exposure control terminates the exposure when
Sufficient radiation reaches the image receptor
50
Thermionic emission at the filament determines the _______ across the x-ray tube during an exposure
Milliamperage
51
Approximately ______% of the kinetic energy of the projectile electrons is converted to x-rays at the target
1%
52
Characteristic x-rays are produced by
Released binding energy
53
Most of the x-rays produced at the target are
Bremsstrahlung
54
An increase in mAs would ______ the ______ of the emission spectrum
Increase, amplitude alone
55
When electrons bombard the target _____% Of their kinetic energy is converted to heat
99
56
What is produced when the project electron excites an outer shell electron
Heat
57
In a tungsten targeted x-ray tube operated at 90 KVP the most abundant x-ray would be a
30 kev Brem X-ray
58
Which of the following is an advantage of the rotating anode tube over the stationary anode tube
Higher heat capacity
59
The x-ray tube current is
Controlled by the filament current
60
How does added filtration affect the emission spectrum
Reduced amplitude and a shift to the right
61
To maintain exposure on a radiograph and increase of 15% in KVP must be accompanied by a _____ reduction in mAs
50%
62
At 55KVP ______ of the x-rays produced Are bremsstrahlung
100%
63
An increase in KVP would _______ the ______ of the emission spectrum
Increase, amplitude and position
64
The wavelength of an x-ray
Becomes longer as projectile electron kinetic energy is reduced
65
When distance is increased x-ray quantity at that distance
Decreases in proportion to the distance squared
66
If radiographic technique is 74 KVP and 80 mAs
Brem x-ray energy increases if the voltage is increased to 84 KVP
67
X-ray tube current is usually measured in which of the following
Milliamperes
68
An increase in KVP results in an increase in
Radiation quality
69
Bremsstrahlung x-rays are produced by ______ ______ at the target
Slowing electrons
70
The useful characteristic x-rays from tungsten targets are ______ xrays
K-shell
71
Bremsstrahlung radiation is produced by
Conversion of projectile electron kinetic energy to electromagnetic energy
72
The intensity of x-ray exposure is best represented by
The area under the emission spectrum
73
In an average radiographic technique is used
Most x-rays are bremsstrahlung
74
A 15% increase in KVP is equivalent to
Doubling the mAs
75
The _____ is the source of radiation in the x-ray tube
Focal spot
76
The formula for heat units HU In a single phase high voltage generator is
KVP x mA x s
77
If the distance from the S ID is reduced by half how is the x-ray intensity at the image affected
It is increased four times
78
How would the bremsstrahlung spectrum change of operation at 80 KVP 200 MA 100 ms or change to 64 KVP 200 MA and 100 ms
It would shift to the left and the amplitude would be lower
79
Which of the following factors principally accounts for the reduced x-ray intensity at low energy
Added filtration
80
The heel effect occurs because of
X-ray absorption in the anode
81
Which is the most appropriate measure of x-ray beam quality
HVL
82
Which characteristic is reduced as x-ray energy increases
X-ray wavelength
83
The number of x-rays in the useful beam defined x-ray
Quantity
84
Normally the x-ray emission spectrum contains
Both characteristic and bremsstrahlung x-rays
85
The x-ray intensity is lower on the anode side of the tube because of the
Heel affect
86
Thermionic emission refers to
Electron emission from a heated source
87
The amplitude of the bremsstrahlung x-ray emission spectrum has
Maximum value at energy approximately 1/3 of the KVP
88
As the x-ray tube ages the inside can become coated with tungsten which can cause ____ in the tube
Arcing
89
The primary purpose of the glass envelope of an x-ray tube is to
Provide a vacuum
90
Which of the following statements applies to the x-ray emission spectrum
The target material affects the amplitude of bremsstrahlung x-rays
91
When the mass is increased x-ray quantity
Increases proportionately
92
Electron interactions at the inner shell of the target Atoms produce ____ radiation
Characteristic
93
It is often stated that mAs Controls quantity and KVP controls
Quality
94
An x-ray beam that could pass through dense tissue would have high
Both A & B
95
However it should be clear that mAs controls quantity and kVP controls
Quality and quantity
96
High capacity to rotators revolve at
10,000 RPM
97
Characteristic k shell x-ray is having an effective energy of
69KEV
98
The penetrability of an x-ray beam is called x-ray
Quality
99
The external structure of the x-ray tube includes a support structure of the protective housing and the
Glass envelope
100
The output intensity of an x-ray tube
Is primarily due to Brem x-rays
101
In ______ there is complete absorption of the incident x-ray photon
Photoelectric interaction
102
In the x-ray department patients receive more exposure (tissue ionization) with _______ Than with other forms of radiation - tissue interaction
Photoelectric interaction
103
When creating a radiograph
Low KVP is necessary when imaging soft tissue because it leads to high photo electric effect
104
High KVP in chest radiography will
Reduce patient dose
105
In a Compton interaction the scattered x-ray usually has
Less energy than the incident x-ray
106
Interaction that does not cause ionization
Classical scattering
107
The reduction of the intensity of an x-ray beam after passing through tissues is called
Attenuation
108
A negative contrast agent example would be
Air
109
Do use of contrast agents increases the amount of
All of the above
110
Which interaction creates the most occupational exposure and diagnostic radiography
Compton scattering
111
Basically an x-ray image results from
A & c
112
The results of photoelectric interaction are
One electron and a characteristic x-ray
113
Differential absorption is dependent on the
All above
114
As KVP ______ The probability of photoelectric absorption ______
Increases, decreases
115
The photo electric effect is
Complete absorption of an x-ray with the subsequent emission of an electron
116
Which of the following interactions involves no energy exchange
Classical scattering
117
Which of the following has the highest mass density
Bone
118
The probability of an increase in photoelectric interaction will occur with
Increasing atomic Number absorbers
119
Only at energies above 10 MEV can ________ take place
Photo disintegration
120
The Compton effect result in
A scattered x-ray whose wavelength is greater than that of the incident x-ray
121
The incident x-ray interacts with an outer shell electron ejected and continues in an altered direction the interaction is
Compton scattering
122
Mass density is
Best described in B and C
123
During photoelectric interaction
An electron is emitted from the atom
124
Which x-ray interaction involves the ejection of the K shell electron
Photoelectric absorption
125
Which of the following occurs in Compton interaction
And Atom is ionized
126
Two primary forms of x-ray interaction in the diagnostic range are
Compton scattering and photoelectric absorption
127
When very high energy x-rays escape interaction with electrons and the nuclear electrostatic field
All of the above
128
Compton scatter is directed at _____ angle from the incident beam
Any
129
The photo electric affect is principally associated with which of the following
Absorption of an x-ray
130
The scattered x-ray from a constant interaction has a _______ wavelength than the incident photon
Longer
131
In which of the following tissues does differential absorption most depend on differences of mass density
Lung and bone
132
Differential absorption although a complicated process is basically the result of differences between
Photo electric affect and transmission
133
Increasing KVP an x-ray imaging well
Reduce skin dose
134
Which of the following is not one of the five basic x-ray interactions with matter
Bremsstrahlung
135
Occurs only at the very high energy is used in radiation therapy in nuclear medicine PET imaging
Pair production
136
The Compton effect is characterized by
Partial transfer of energy upon collision
137
To optimize x-ray mammography
Low KVP is necessary to take advantage of the photo electric affect
138
Attenuation is caused by
Both a and B
139
As x-ray energy increases there is reduced
Reduced absolute photo electric effect
140
X-rays transmitted without interaction contribute to
The radiographic image
141
At low energy is the majority of x-ray interactions are
Photo electric
142
Total absorption of the energy of the incident incoming photon occurs in
Photoelectric interaction
143
Which of the following interactions contributes to Image noise
Compton
144
The energy of a Compton scattered x-ray is equal to
The difference between the energy of the incident x-ray and the energy of the ejected electron
145
Compton interactions photo electric absorption and transmitted x-rays all contribute to
Differential absorption
146
Barium is a good contrast agent because of its
High atomic number
147
When the mass density of the absorber is ______ it results in ______ Compton scatter
Increased, increased
148
Anatomic structures that readily transmit x-rays
Are radio Lucent
149
The photo electric affect
A & C are true
150
Feeling the fluoroscopic image in magnification mode increases
All of the above
151
Magnifying the viewed area on the patient by decreasing the image intensifier field size will do what your skin dose
Increase
152
The maximum allowed absorbed equivalent dose for radiographers is
5 rem
153
For those units where possible increasing the kilovoltage (penetrating power) of the beam will do what to patient dose
Decrease
154
A medical physicist will remeasure typical dose rates for each fluoroscopy unit every
Year
155
Nationwide the most common operator error for the C-arm units that unnecessarily increase patient dose is
Having the image intensifier too close to the skin
156
After a lead apron the most effective device for reducing the radiation risk to an individual is
Thyroid shield
157
The fluoroscope was invented by
Thomas Edison
158
Compared with a radiographic exam the purpose of fluoroscopy PE exams are to visualize
Dynamic images
159
Automatic brightness stabilization (ABS) is designed to compensate for changes in which of the following
Patient composition
160
Where are the rods located in the eye
Cornea
161
What is the function of the iris
Control the light level
162
The cones in the eye are
Photo optic vision
163
Rods are used principally for which of the following
Dim lighting
164
In general during fluoro exams as compared to radiography use
Lower ma
165
Which of the following describes the fluoroscopy system used to maintain constant image intensity
ABS
166
Emission of electrons from an illuminated source
Photo electric emission
167
At what stage of the image intensified fluoro is the number of image forming photons the lowest
Entering input phosphor
168
Image intensifier brightness gain increases with increasing
Flux gain
169
When an image intensifier receives x-rays at the input phosphor what is admitted at the output phosphor
Visible light
170
Which of the following is the input phosphor of the image intensifier
Cesium iodide
171
Which of the following is the output phosphor of the image intensifiers
Zinc cadmium sulfide
172
The photocathode converts
Visible light into electrons
173
Which of the following is a component of the image intensifier responsible for focusing the electron beam
Electrostatic lens
174
The ability of an image intensifier to enhance image illumination is called
Brightness gain
175
An image that displays vignetting
Dim around the periphery
176
What is the camera tube most used in television fluoroscopy
Vidacon
177
What is the principal disadvantage of the couple in TV camera to the image intensifier with the use of fiber optics
Photo spot camera can’t be used
178
What is the most important component of a television monitor
Cathode x-ray tube
179
What is the electron beam of the television camera tube
Modulated
