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Oral Radiology > Production of X-rays- Lecture 3 & 4 > Flashcards

Production of X-rays- Lecture 3 & 4 Flashcards

1
Q

Label the following image:

A

A) Control Panel
B) Control Panel
C) PID
D) Tubehead
E) X-ray Tube
F) Power Supply (Generator)
G) Extension Arm

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2
Q

The tube head of the x-ray machine is made up of:

A
  1. x-ray tube
  2. power supply (generator)
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3
Q

What component of the X-ray machine does this image show?

A

Control Panel

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4
Q

What can be viewed/ adjusted on the control panel:

A
  1. exposure time
  2. kVp selector
  3. mA selector
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5
Q

What type of exposure button do we have on our control panel?

A

Dead-man type

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6
Q

The ____ light and ____ signal must both be present on the control panel

A

indicator light; audible signal

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7
Q

Label the following components of the X-ray tube head:

A

a) x-ray tube
b) step-down transformer
c) step-up transformer
d) cathode (-)
e) anode (+)
f) filament circuit
g) tube head seal
h) aluminum discs
i) lead collimator
j) position indicating device (PID)
k) unleaded glass window of X-ray tube
l) insulating oil
m) metal housing of X-ray tube head

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8
Q

label the following image

A

a) tube head
b) PID

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9
Q

Label the following image:

A

a) x-ray tube
b) yoke
c) oil
d) power supply
e) collimator
f) aiming cylinder
g) x-ray beam
h) aluminum filter
i) power supply

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10
Q

List the important components of the X-ray tube head: (6)

A
  1. glass envelope
  2. insulating oil
  3. metal housing
  4. tube window
  5. aluminum filters
  6. lead collimator
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11
Q

Label the following image:

A

a) film & electron cloud
b) focal spot on tungsten target
c) glass envelope
d) vacuum
e) copper stem
f) anode (+)
g) useful x-ray beam
h) tube window
i) cathode (-)
j) electronic focusing cup

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12
Q

The cathode contains:

A
  1. filament
  2. focusing cup
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13
Q

The cathode filament is made of:

A

tungsten

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14
Q

What part of the cathode is made of tungsten?

A

the filament

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15
Q

Source of electrons in the X-ray tube:

A

cathode filament

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16
Q

Is heated with a low voltage source and emits electrons at a rate proportional to its temperature (thermionic emission)

A

cathode filament

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17
Q

The cathode filament is heated with a ___ voltage source and emits ___ at a rate proportional to ___.

A

low voltage source; electrons; its temperature

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18
Q

The cathode filament emits electron through:

A

thermionic emission

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19
Q

The cathode focusing cup is made of:

A

molybdenum

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20
Q

What is the charge of the cathode focusing cup?

A

negatively charged

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21
Q

Focuses the electrons into a narrow beam directed to the focal spot (+)

A

cathode focusing cup

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22
Q

The cathode focusing cup focuses the electrons into a ____ directed to the ____.

A

narrow beam; focal spot

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23
Q

What is the charge of the focal spot?

A

positive

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24
Q

The anode contains:

A
  1. Tungsten target
  2. Copper stem
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25
Q

The tungsten target of the anode functions to:

A

transform the kinetic energy of the colliding electrons into x-ray photons

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26
Q

Functions to transform the kinetic energy of the colliding electrons into x-ray photons:

A

Anode tungsten target

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27
Q

Highly inefficient: produces 99% heat and 1% x-rays:

A

Anode tungsten target

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28
Q

Describe the efficiency of the anode tungsten target:

A

Highly inefficient: produces 99% heat and 1% x-rays

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29
Q

Works as a thermal conductor to remove the heat from the tungsten avoiding target melting:

A

Anode copper stem

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30
Q

The anode copper stem works as a ____ to remove that from the tungsten, avoiding ___.

A

thermal conductor; target melting

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31
Q

Why is tungsten a good target material? (5)

A
  1. High atomic number
  2. High melting point
  3. High thermal conductivity
  4. Low vapor pressure
  5. Cheap
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32
Q

What does the high atomic number of tungsten allow for?

A

efficient production of x-rays

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33
Q

Tungsten has a high melting point of ____. What does this allow for?

A

3422 celcius; to withstand the heat produced

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34
Q

What is the significance of the high thermal conductivity displayed by tungsten?

A

Allows it to dissipate the heat produced away from the target

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35
Q

The low vapor pressure of tungsten helps to:

A

maintain vacuum in the tube at high temps

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36
Q

Conditions necessary for x-ray production include: (4)

A
  1. separation of electrons
  2. production of high speed electrons
  3. concentration of electrons
  4. sudden stoppage of electron steam
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37
Q

What gives the energy to heat the filament?

A

The step-down transformer

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38
Q

Low voltage filament current heats the tungsten filament to incandescence with resultant:

A

separation of outer shell electrons from tungsten atom (boiling off)

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39
Q

Low voltage filament current heats the tungsten filament to incandescence with resultant separation of outer shell electrons from the tungsten atom (boiling off). This separation of electrons is called:

A

thermionic emission

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40
Q

Label the following image:

A

a) step-down transformer
b) 6-12 volts
c) focusing cup
d) tungsten filament
e) electron cloud

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41
Q

The ____ is produced between the cathode and anode by applying a high voltage between them

A

high potential difference

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42
Q

The high potential difference between the cathode and anode contributes to:

A

Production of high-speed electrons

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43
Q

The high potential difference is produced between the cathode and anode by:

A

Applying a high voltage between them

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44
Q

By producing a high potential difference between the cathode and anode, the electrons are accelerated to approximately:

A

0.5x the speed of light

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45
Q

What makes the potential difference between the anode and cathode sufficient enough to accelerate the electrons?

A

step-up transformer

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46
Q

Label the following image:

A

a) 6-12 volts
b) 60k-90k volts
c) 60-90 kVp
d) 60k-90k volts

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47
Q

After electrons are accelerated toward the target, what occurs?

A

concentration of electrons

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48
Q

The electron beam is focused by the _____ (____ charge) and directed towards the ____.

A

focusing cup (negative charge); focal spot

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49
Q

In what step is the electron beam focused by the focusing cup (negative charge) and directed towards the focal spot?

A

Concentration of electrons

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50
Q

Following the concentration of electrons, is the:

A

sudden stoppage of electron steam

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51
Q

X-rays are produced whenever high speed electrons are suddenly _____ or brought to a stop when they pass close to the nuclei of a ______ such as ____.

A

decelerated; high Z absorbing material; Tungsten

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52
Q

What are the four basic steps to the production of an x-ray?

A
  1. Separation of electrons
  2. Production of high-speed electrons
  3. Concentration of electrons
  4. Sudden stoppage of electron stream
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53
Q

What step of x-ray production is being described below?

Low voltage filament current heats the tungsten filament to incandesce with resultant separation of outer shell electrons from tungsten atom (“boiling off”).

A
  1. Separation of electrons
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54
Q

What step of x-ray production is being described below?

High potential difference is produced cathode and anode by applying high voltage between them

A
  1. Production of high speed electrons
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55
Q

What step of x-ray production is being described below?

Electron beam is focused by the focusing cup (negatively charged) and directed towards the focal spot (positively charged)

A
  1. Concentration of electrons
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56
Q

What step of x-ray production is being described below?

Upon striking the focal spot in the anode, the electron stream is stopped abruptly and kinetic energy of the electron stream undergoes conversion to greater than 99% heat and less than 1% radiation. Copper stem removes the heat from the tungsten

A
  1. Sudden stoppage of electron stream
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57
Q

The low voltage supply for the separation of electrons comes from the:

A

step-down transformer

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58
Q

During the separation of electrons (step 1) the low voltage filament current heats the tungsten filament to incandesce with resultant:

A

separation of outer shell electrons from tungsten atom (“boiling off”)

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59
Q

During the separation of electrons (step 1), the low voltage filament current heats the tungsten filament to incandesce with resultant separation of outer shell electrons from tungsten atom (“boiling off”). This separation is called:

A

thermionic emission

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60
Q

The separation of electrons is accomplished through:

A

thermionic emission

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61
Q

During the production of high-speed electrons (step 2), the high potential difference is produced between:

A

the cathode and the anode

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62
Q

During the production of high-speed electrons (step 2), the high potential difference produced between the cathode and anode occurs by:

A

applying high voltage between them

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63
Q

During the concentration of electrons (step 3), the electron beam is focused by the ___.

A

focusing cup

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64
Q

Describe the charge of the focusing cup:

A

negatively charged

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65
Q

During the concentration of electrons (step 3), the electron beam is focused by the focusing cup (negatively charged) and directed towards the:

A

focal spot (positively charged)

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66
Q

During the sudden stoppage of electron stream (step 4), upon striking the focal spot in the anode, the electron stream is:

A

stopped abruptly

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67
Q

During the sudden stoppage of electron stream (step 4), upon striking the focal spot in the anode, the electron stream is stopped abruptly and the kinetic energy of the electron stream undergoes conversion to:

A

greater than 99% heat and less than 1% radiation

68
Q

During the sudden stoppage of electron stream (step 4), what removes the heat from the tungsten?

A

copper stem

69
Q

During the sudden stoppage of electron stream (step 4), the copper stem removes the heat from:

A

tungsten

70
Q

Label the cathode and anode:

A

A) Cathode
B) Anode

71
Q

What are the two main parts of the cathode?

A
  1. filament
  2. focusing cup
72
Q

The filament of the cathode is made of:

A

tungsen

73
Q

The filament of the cathode is the:

A

source of electrons

74
Q

The filament of the cathode is heated with:

A

a low voltage source

75
Q

The filament of the cathode is heated with a low voltage source and emits:

A

electrons at a rate proportional to its temperature

76
Q

The filament of the cathode is heated with a low voltage source and emits electrons at a rate proportional to its temperature. This is known as;

A

thermionic emission

77
Q

The focusing cup of the cathode is made of:

A

molybdenum

78
Q

What is the charge of the focusing cup of the cathode?

A

negatively charged

79
Q

Focuses electrons into a narrow beam directed to the focal spot (+):

A

focusing cup of cathode

80
Q

The focusing cup of the cathode focuses the electrons into a narrow beam directed to the:

A

focal spot (+)

81
Q

What are the two main parts of the anode?

A
  1. tungsten target
  2. copper stem
82
Q

The tungsten target of the anode is responsible for:

A

transforming the kinetic energy of the colliding electrons into x-ray photons

83
Q

Describe the efficiency of the tungsten target at transforming the kinetic energy of the colliding electrons into x-ray photons:

A

highly inefficient: produces 99% heat and 1% x-rays

84
Q

Where are x-rays produced?

A

The tungsten target of the anode

85
Q

Why is tungsten a good target material? (Anode) (4)

A
  1. high atomic number
  2. high melting point
  3. high thermal conductivity
  4. low vapor pressure
86
Q

What is the function of the copper stem in the anode?

A

works as a thermal conductor to remove the heat from the tungsten avoiding target melting/ overheating

87
Q

The copper stem in the anode works as a thermal conductor to remove heat from the tungsten avoiding:

A

target melting/overheating

88
Q

What are the two ways to prevent overheating of the tungsten target?

A

stationary anode and rotating anode

89
Q

Angling the target to achieve a smaller effective focal spot than the actual focal spot. Results in a sharper radiographic image

A

stationary anode

90
Q

What type of image is the result of a stationary anode:

A

shaper radiographic image

91
Q

What principle is described by having a stationary anode:

A

line focus principle

92
Q

Projection of the focal spot perpendicular to the target:

A

actual focal spot

93
Q

Projection of the focal spot perpendicular to the electron beam:

A

effective focal spot

94
Q

The effective focal spot is always ____ than the actual focal spot

A

smaller

95
Q

What is the purpose of a transformer?

A

Electromagnetic device that either increases or decreases the voltage in a circuit

96
Q

Electromagnetic device that either increases or decreases the voltage in a circuit

A

transformer

97
Q

What are the three types of transformers?

A
  1. step-down transformer (filament transformer)
  2. step-up transformer (high voltage)
  3. autotransformer
98
Q

What transformer is used to heat the filament?

A

step-down transformer

99
Q

Converts 110 or 220 volts to 3-5 volts:

A

step-down transformer

100
Q

The step-down transformer converts ____ volts to ____ volts

A

110 or 220 volts to 3-5 volts

101
Q

What transformer is involved in the low voltage circuit?

A

step-down transformer

102
Q

The step-down transformer is regulated by the:

A

mA switch

103
Q

What does increasing mA do to the step-down transformer?

A

increasing mA increases the NUMBER of electrons emitted

104
Q

What is powered by the step-down transformer?

A

Cathode

105
Q

What transformer converts 110 or 220 volts to 60k-100k volts?

A

step-up transformer

106
Q

Why does the step-up transformer increase the voltage so substantially?

A

to move electrons across the tube (high-voltage circuit)

107
Q

What transformer is involved in the high-voltage circuit?

A

step-up transformer

108
Q

The step-up transformer is regulated by:

A

kVp setting

109
Q

What does increasing the kVp setting do to the step-up transformer?

A

increases the ENERGY of electrons traveling from cathode to anode

110
Q

The ___ is powered by the step-up transformer

A

anode

111
Q

Each half cycle (1/120 of a second) the anode is positive and attracts the electrons from the cathode

A

x-radiation is produced

112
Q

Each alternate half cycle (1/120 of a second) the anode is negative and therefore there is no attraction for electrons

A

no x-radiation is produced

113
Q

X-radiation is produced when the anode is:

A

positive

114
Q

No x-radiation is produced when the anode is:

A

negative

115
Q

Wave of periods of producing and not producing x-rays:

A

alternating current

116
Q

The cathode and anode alternate between positive and negative which causes x-rays to be produced only half of the time

A

alternating current

117
Q

During an alternating current, x-rays are produced:

A

half of the time

118
Q

During an alternating current, the cathode and anode alternate between:

A

positive and negative

119
Q

Current is always running in the same direction and always producing x-rays:

A

direct current

120
Q

Direct current keeps the:

A

cathode negative and anode positive

121
Q

During a direct current, the current is always running in ____ and always producing ___.

A

same direction; x-rays

122
Q

Functions to decrease radiation dose and exposure time:

A

direct current/constant potential

123
Q

Direct current/constant potential function too:

A

decrease radiation dose and exposure time

124
Q

Diamond that redirects alternating pathways/non-producing x-rays from the filament to the target anode regardless of + or -:

A

rectifier

125
Q

The rectifier (diamond) redirects alternating pathway/ non-producing x-rays from the filament to the target anode regardless of:

A

+ or - charge

126
Q

Flow of electrons through an electrical conductor:

A

electricity

127
Q

Amount of electrons flowing through a conductor per second. Measured in amperes (A)

A

current

128
Q

Path of electrical current:

A

circuit

129
Q

Difference in electrical potential energy between two points in an electrical circuit. Measured in volts (V)

A

Voltage (potential difference)

130
Q

Current is measured in:

A

amperes (A)

131
Q

Voltage is measured in:

A

Volts (V)

132
Q

Low voltage filament current heats the tungsten filament to incandescence with resultant separation n of outer shell electrons from tungsten atom (“boiling off”):

A

thermionic emission

133
Q

Controls heating of the filament. This controls the number of electrons emitted and number of x-rays produced:

A

mA

134
Q

Controls the acceleration/energy of electrons from cathode to anode:

A

kV

135
Q

How does mA effect x-ray production?

A

controls heating of the filament which controls the number of electrons emitted and the number of x-rays produced

136
Q

How does kVp effect x-ray production?

A

Controls the acceleration/energy of electrons from cathode to anode

137
Q

The voltage difference between the filament/cathode and target/anode:

A

kVp

138
Q

Bremsstrahlung x-ray production describes:

A

electron to nucleus interaction

139
Q

High velocity electrons (directed towards target) either slow down or stop when they come close to the nucleus of the atoms and part of their energy is transferred as x-rays:

A

Bremsstrahlung x-ray production

140
Q

Bremsstrahlung x-ray production is also known as:

A

breaking radiation

141
Q

According to Bremsstrahlung x-ray production, the high velocity electrons (directed towards the target) either ____ or ____ when they come close to the nucleus of the atoms and part of their energy is transferred as ____.

A

slow down; stop; x-rays

142
Q

In Bremmsstrahlung x-ray production, all electrons do not attain the same ____.

A

velocity

143
Q

In Bremmsstrahlung x-ray production, all electrons do not attain the same velocity, why is this?

A

Because of wide distribution of wavelengths (heterogeneous)

144
Q

What happens to electrons when they interact with tungsten atoms in Bremsstrahlung x-ray production?

A

electrons lose their energies in random fashions

145
Q

In Bremsstrahlung x-ray production, when an electron has a head on collision with the nucleus, this causes:

A

electron to stop, producing a maximum energy photon

146
Q

Bremsstrahlung spectrum is a ____ spectrum

A

continuous emission spectrum

147
Q

Bremsstrahlung spectrum is a continuous emission spectrum because bremsstrahlung radiation:

A
  1. increases with increasing voltage and atomic number of the target
  2. different energies of of x-rays are emitted based on where electron hits the nucleus
148
Q

Bremsstrahlung spectrum is a continuous emission spectrum because bremsstrahlung radiation _____ with increasing voltage and atomic number of the target

A

increases

149
Q

Bremsstrahlung spectrum is a continuous emission spectrum because different energies of x-rays are emitted based on:

A

where electron hits the nucleus

150
Q

In Bremsstrahlung spectrum, maximum energy occurs when:

A

electron hits nucleus and is stopped completely

151
Q

The process of characteristic x-ray production involves ____ interaction

A

electron to electron

152
Q

In _____ x-ray production, a few electrons interact with the tungsten target orbital electron, imparting enough energy to ionize the tungsten. This removes an electron from the orbit and immediately electron is filled from outer shell and energy is emitted

A

characteristic x-ray production

153
Q

In characteristic x-ray production, the energy emitted by the electron is equivalent to:

A

the difference in the binding energies of the two shells/ orbitals

154
Q

Characteristic x-ray production:

L to K transition =

M to K transition =

A

L to K = 57,400 eV

M to K= 66,700 eV

155
Q

Explain why characteristic radiation is called discrete radiation:

A

discrete energy is imparted to the newly formed radiation which is “characteristic” of the atom type and orbital from which came

156
Q

_____ % of the diagnostic x-ray beam is characteristic radiation while ____% is Bremsstrahlung radiation.

A

30%; 70%

157
Q

The majority of the diagnostic x-ray beam is ___ radiation

A

Bremsstrahlung (70%)

158
Q

A rotating anode allows heat at the focal spot to spread out over:

A

A large surface area (dark band)

159
Q

What type of anode is used in medical devices?

A

rotating anode

160
Q

Determines the amount of time the high voltage circuit is applied across the X-ray tube (amount of time the x-rays are produced)

A

exposure timer

161
Q

Delay of 1/2 second to heat the filament:

A

time-delay circuit

162
Q

Actual time of exposure:

A

timing circuit

163
Q

What three controls are on the control panel?

A
  1. kV (kilovoltage)
  2. mA (milliamperage)
  3. Exposure time
164
Q

Controls the acceleration of the electrons from the cathode to the anode:

A

kV (kilovoltage)

165
Q

Controls heating of the filament:

A

mA (miliamperage)

166
Q

Controls the time in which x-rays are produced:

A

exposure time

Oral Radiology (21 decks)

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