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Radiology > Semester 2 physics exams > Flashcards

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

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2
Q

Electron emission from a heated source

A

Thermionic emission

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3
Q

A radiographic technique calls for 800 MA, 1/20 s exposure what is the mAs

A

40

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4
Q

The difference between x-rays and gamma rays is

A

Their origin

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5
Q

Three main parts of the x-ray imaging system are the x-ray tube, _______, and ______

A

Operating console high-voltage generator

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6
Q

When considering the electromagnetic spectrum photons of a radio broadcast have relatively

A

Low energy and long wavelengths

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7
Q

Regarding the induction motor on the x-ray tube the only part to rotate is the

A

Rotor

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8
Q

Radio waves, light, and x-rays are all examples of ______ energy

A

Electromagnetic

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9
Q

Convert AC to DC

A

Rectifier

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10
Q

A diode allows electrons to flow _____

A

From cathode to anode

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11
Q

Which of the following principles of rectification produces the maximum efficiency of x-ray production

A

High frequency

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12
Q

As compared with particulate radiation, electromagnetic radiation Is

A

More penetrating

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13
Q

In modern imaging systems the components for rectification are

A

Solid state semi conductors

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14
Q

According to quantum mechanics the energy of an x-ray is

A

Inversely proportional to its wavelength

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15
Q

When a step up transformer is in use

A

The secondary voltage is greater than the primary voltage

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16
Q

The development of modern quantum mechanics is attributed to

A

Max Planck

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17
Q

Which of the following has a constant value for all electromagnetic radiation

A

Velocity

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18
Q

The mAs timer is usually set to give the ______ mA at the _____ time

A

Highest, shortest

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19
Q

Voltage across the x-ray tube is most constant with

A

High frequency generator’s

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20
Q

In AEC device can

A

Use an ionization chamber between the patient and the image receptor

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21
Q

The high-voltage generator contains a high-voltage transformer and the

A

Rectifiers

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22
Q

The difference in the waveform between the primary and secondary sides of the high-voltage transformer is the

A

Amplitude

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23
Q

When compared with visible light x-rays have shorter

A

Wavelength

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24
Q

Voltage across the x-ray tube is most constant with

A

High frequency generator’s

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25
Q

X-ray tube current is usually measured in which of the following

A

Amperes

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26
Q

Smallest quantity of any type of electromagnetic radiation is a

A

Photon

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27
Q

The four properties of photons are

A

Frequency, wavelength, velocity, amplitude

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28
Q

The principal purpose of the high-voltage transformer is to do which of the following

A

Increase voltage

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29
Q

Line compensation is

A

Required to stabilize voltage

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30
Q

X-ray transformers operate on the principle of

A

Mutual induction

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31
Q

The x-ray generator with the lowest power rating is the ______ imaging system

A

Single phase

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32
Q

Variations in power distribution do the x-ray machine Are corrected by The

A

Line voltage compensator

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33
Q

For any electromagnetic radiation and increase in frequency result in

A

An increase in energy

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34
Q

X-rays and gamma rays are both examples of electromagnetic radiation in addition they both have

A

No electrostatic charge

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35
Q

X-rays have ____ mass and _____ charge

A

No mass no charge

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36
Q

The most accurate type of timer is the

A

Electronic timer

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37
Q

A transformer operates on

A

AC NOT DC

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38
Q

What is the removal of an electron from an Atom called

A

Ionization

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39
Q

A single-phase waveform has a ______ ripple

A

100%

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40
Q

If an automatic exposure control device ____ is required

A

Back up timer

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41
Q

The energy of an x-ray photon is directly proportional to its

A

Frequency

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42
Q

Bone that absorbs x-radiation is called

A

Radiopaque

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43
Q

The inverse square law states that

A

Intensity is inversely proportional to the square of the distance

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44
Q

The auto transformer has _____ windings

A

1

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45
Q

The exposure timer on a three phase radiographic imaging system will

A

Be electronic

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46
Q

Which of the following is greater for a 30 KEV x-ray then a 60 KEV x-ray

A

Wavelength

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47
Q

In radiographs of bony structures in bedded in soft tissue the bone is

A

Radiopaque

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48
Q

The inverse square law involving distance could be applied to

A

All of the above

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49
Q

The automatic exposure control terminates the exposure when

A

Sufficient radiation reaches the image receptor

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50
Q

Thermionic emission at the filament determines the _______ across the x-ray tube during an exposure

A

Milliamperage

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51
Q

Approximately ______% of the kinetic energy of the projectile electrons is converted to x-rays at the target

A

1%

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52
Q

Characteristic x-rays are produced by

A

Released binding energy

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53
Q

Most of the x-rays produced at the target are

A

Bremsstrahlung

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54
Q

An increase in mAs would ______ the ______ of the emission spectrum

A

Increase, amplitude alone

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55
Q

When electrons bombard the target _____% Of their kinetic energy is converted to heat

A

99

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56
Q

What is produced when the project electron excites an outer shell electron

A

Heat

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57
Q

In a tungsten targeted x-ray tube operated at 90 KVP the most abundant x-ray would be a

A

30 kev Brem X-ray

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58
Q

Which of the following is an advantage of the rotating anode tube over the stationary anode tube

A

Higher heat capacity

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59
Q

The x-ray tube current is

A

Controlled by the filament current

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60
Q

How does added filtration affect the emission spectrum

A

Reduced amplitude and a shift to the right

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61
Q

To maintain exposure on a radiograph and increase of 15% in KVP must be accompanied by a _____ reduction in mAs

A

50%

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62
Q

At 55KVP ______ of the x-rays produced Are bremsstrahlung

A

100%

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63
Q

An increase in KVP would _______ the ______ of the emission spectrum

A

Increase, amplitude and position

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64
Q

The wavelength of an x-ray

A

Becomes longer as projectile electron kinetic energy is reduced

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65
Q

When distance is increased x-ray quantity at that distance

A

Decreases in proportion to the distance squared

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66
Q

If radiographic technique is 74 KVP and 80 mAs

A

Brem x-ray energy increases if the voltage is increased to 84 KVP

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67
Q

X-ray tube current is usually measured in which of the following

A

Milliamperes

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68
Q

An increase in KVP results in an increase in

A

Radiation quality

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69
Q

Bremsstrahlung x-rays are produced by ______ ______ at the target

A

Slowing electrons

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70
Q

The useful characteristic x-rays from tungsten targets are ______ xrays

A

K-shell

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71
Q

Bremsstrahlung radiation is produced by

A

Conversion of projectile electron kinetic energy to electromagnetic energy

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72
Q

The intensity of x-ray exposure is best represented by

A

The area under the emission spectrum

73
Q

In an average radiographic technique is used

A

Most x-rays are bremsstrahlung

74
Q

A 15% increase in KVP is equivalent to

A

Doubling the mAs

75
Q

The _____ is the source of radiation in the x-ray tube

A

Focal spot

76
Q

The formula for heat units HU In a single phase high voltage generator is

A

KVP x mA x s

77
Q

If the distance from the S ID is reduced by half how is the x-ray intensity at the image affected

A

It is increased four times

78
Q

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

A

It would shift to the left and the amplitude would be lower

79
Q

Which of the following factors principally accounts for the reduced x-ray intensity at low energy

A

Added filtration

80
Q

The heel effect occurs because of

A

X-ray absorption in the anode

81
Q

Which is the most appropriate measure of x-ray beam quality

A

HVL

82
Q

Which characteristic is reduced as x-ray energy increases

A

X-ray wavelength

83
Q

The number of x-rays in the useful beam defined x-ray

A

Quantity

84
Q

Normally the x-ray emission spectrum contains

A

Both characteristic and bremsstrahlung x-rays

85
Q

The x-ray intensity is lower on the anode side of the tube because of the

A

Heel affect

86
Q

Thermionic emission refers to

A

Electron emission from a heated source

87
Q

The amplitude of the bremsstrahlung x-ray emission spectrum has

A

Maximum value at energy approximately 1/3 of the KVP

88
Q

As the x-ray tube ages the inside can become coated with tungsten which can cause ____ in the tube

A

Arcing

89
Q

The primary purpose of the glass envelope of an x-ray tube is to

A

Provide a vacuum

90
Q

Which of the following statements applies to the x-ray emission spectrum

A

The target material affects the amplitude of bremsstrahlung x-rays

91
Q

When the mass is increased x-ray quantity

A

Increases proportionately

92
Q

Electron interactions at the inner shell of the target Atoms produce ____ radiation

A

Characteristic

93
Q

It is often stated that mAs Controls quantity and KVP controls

A

Quality

94
Q

An x-ray beam that could pass through dense tissue would have high

A

Both A & B

95
Q

However it should be clear that mAs controls quantity and kVP controls

A

Quality and quantity

96
Q

High capacity to rotators revolve at

A

10,000 RPM

97
Q

Characteristic k shell x-ray is having an effective energy of

A

69KEV

98
Q

The penetrability of an x-ray beam is called x-ray

A

Quality

99
Q

The external structure of the x-ray tube includes a support structure of the protective housing and the

A

Glass envelope

100
Q

The output intensity of an x-ray tube

A

Is primarily due to Brem x-rays

101
Q

In ______ there is complete absorption of the incident x-ray photon

A

Photoelectric interaction

102
Q

In the x-ray department patients receive more exposure (tissue ionization) with _______ Than with other forms of radiation - tissue interaction

A

Photoelectric interaction

103
Q

When creating a radiograph

A

Low KVP is necessary when imaging soft tissue because it leads to high photo electric effect

104
Q

High KVP in chest radiography will

A

Reduce patient dose

105
Q

In a Compton interaction the scattered x-ray usually has

A

Less energy than the incident x-ray

106
Q

Interaction that does not cause ionization

A

Classical scattering

107
Q

The reduction of the intensity of an x-ray beam after passing through tissues is called

A

Attenuation

108
Q

A negative contrast agent example would be

A

Air

109
Q

Do use of contrast agents increases the amount of

A

All of the above

110
Q

Which interaction creates the most occupational exposure and diagnostic radiography

A

Compton scattering

111
Q

Basically an x-ray image results from

A

A & c

112
Q

The results of photoelectric interaction are

A

One electron and a characteristic x-ray

113
Q

Differential absorption is dependent on the

A

All above

114
Q

As KVP ______ The probability of photoelectric absorption ______

A

Increases, decreases

115
Q

The photo electric effect is

A

Complete absorption of an x-ray with the subsequent emission of an electron

116
Q

Which of the following interactions involves no energy exchange

A

Classical scattering

117
Q

Which of the following has the highest mass density

A

Bone

118
Q

The probability of an increase in photoelectric interaction will occur with

A

Increasing atomic Number absorbers

119
Q

Only at energies above 10 MEV can ________ take place

A

Photo disintegration

120
Q

The Compton effect result in

A

A scattered x-ray whose wavelength is greater than that of the incident x-ray

121
Q

The incident x-ray interacts with an outer shell electron ejected and continues in an altered direction the interaction is

A

Compton scattering

122
Q

Mass density is

A

Best described in B and C

123
Q

During photoelectric interaction

A

An electron is emitted from the atom

124
Q

Which x-ray interaction involves the ejection of the K shell electron

A

Photoelectric absorption

125
Q

Which of the following occurs in Compton interaction

A

And Atom is ionized

126
Q

Two primary forms of x-ray interaction in the diagnostic range are

A

Compton scattering and photoelectric absorption

127
Q

When very high energy x-rays escape interaction with electrons and the nuclear electrostatic field

A

All of the above

128
Q

Compton scatter is directed at _____ angle from the incident beam

A

Any

129
Q

The photo electric affect is principally associated with which of the following

A

Absorption of an x-ray

130
Q

The scattered x-ray from a constant interaction has a _______ wavelength than the incident photon

A

Longer

131
Q

In which of the following tissues does differential absorption most depend on differences of mass density

A

Lung and bone

132
Q

Differential absorption although a complicated process is basically the result of differences between

A

Photo electric affect and transmission

133
Q

Increasing KVP an x-ray imaging well

A

Reduce skin dose

134
Q

Which of the following is not one of the five basic x-ray interactions with matter

A

Bremsstrahlung

135
Q

Occurs only at the very high energy is used in radiation therapy in nuclear medicine PET imaging

A

Pair production

136
Q

The Compton effect is characterized by

A

Partial transfer of energy upon collision

137
Q

To optimize x-ray mammography

A

Low KVP is necessary to take advantage of the photo electric affect

138
Q

Attenuation is caused by

A

Both a and B

139
Q

As x-ray energy increases there is reduced

A

Reduced absolute photo electric effect

140
Q

X-rays transmitted without interaction contribute to

A

The radiographic image

141
Q

At low energy is the majority of x-ray interactions are

A

Photo electric

142
Q

Total absorption of the energy of the incident incoming photon occurs in

A

Photoelectric interaction

143
Q

Which of the following interactions contributes to Image noise

A

Compton

144
Q

The energy of a Compton scattered x-ray is equal to

A

The difference between the energy of the incident x-ray and the energy of the ejected electron

145
Q

Compton interactions photo electric absorption and transmitted x-rays all contribute to

A

Differential absorption

146
Q

Barium is a good contrast agent because of its

A

High atomic number

147
Q

When the mass density of the absorber is ______ it results in ______ Compton scatter

A

Increased, increased

148
Q

Anatomic structures that readily transmit x-rays

A

Are radio Lucent

149
Q

The photo electric affect

A

A & C are true

150
Q

Feeling the fluoroscopic image in magnification mode increases

A

All of the above

151
Q

Magnifying the viewed area on the patient by decreasing the image intensifier field size will do what your skin dose

A

Increase

152
Q

The maximum allowed absorbed equivalent dose for radiographers is

A

5 rem

153
Q

For those units where possible increasing the kilovoltage (penetrating power) of the beam will do what to patient dose

A

Decrease

154
Q

A medical physicist will remeasure typical dose rates for each fluoroscopy unit every

A

Year

155
Q

Nationwide the most common operator error for the C-arm units that unnecessarily increase patient dose is

A

Having the image intensifier too close to the skin

156
Q

After a lead apron the most effective device for reducing the radiation risk to an individual is

A

Thyroid shield

157
Q

The fluoroscope was invented by

A

Thomas Edison

158
Q

Compared with a radiographic exam the purpose of fluoroscopy PE exams are to visualize

A

Dynamic images

159
Q

Automatic brightness stabilization (ABS) is designed to compensate for changes in which of the following

A

Patient composition

160
Q

Where are the rods located in the eye

A

Cornea

161
Q

What is the function of the iris

A

Control the light level

162
Q

The cones in the eye are

A

Photo optic vision

163
Q

Rods are used principally for which of the following

A

Dim lighting

164
Q

In general during fluoro exams as compared to radiography use

A

Lower ma

165
Q

Which of the following describes the fluoroscopy system used to maintain constant image intensity

A

ABS

166
Q

Emission of electrons from an illuminated source

A

Photo electric emission

167
Q

At what stage of the image intensified fluoro is the number of image forming photons the lowest

A

Entering input phosphor

168
Q

Image intensifier brightness gain increases with increasing

A

Flux gain

169
Q

When an image intensifier receives x-rays at the input phosphor what is admitted at the output phosphor

A

Visible light

170
Q

Which of the following is the input phosphor of the image intensifier

A

Cesium iodide

171
Q

Which of the following is the output phosphor of the image intensifiers

A

Zinc cadmium sulfide

172
Q

The photocathode converts

A

Visible light into electrons

173
Q

Which of the following is a component of the image intensifier responsible for focusing the electron beam

A

Electrostatic lens

174
Q

The ability of an image intensifier to enhance image illumination is called

A

Brightness gain

175
Q

An image that displays vignetting

A

Dim around the periphery

176
Q

What is the camera tube most used in television fluoroscopy

A

Vidacon

177
Q

What is the principal disadvantage of the couple in TV camera to the image intensifier with the use of fiber optics

A

Photo spot camera can’t be used

178
Q

What is the most important component of a television monitor

A

Cathode x-ray tube

179
Q

What is the electron beam of the television camera tube

A

Modulated

Radiology (13 decks)

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