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RAD1418 > Unit 3: X-ray Production and Anode Heel > Flashcards

Unit 3: X-ray Production and Anode Heel Flashcards

1
Q

What is the negatively charged side of the tube?

A

Cathode

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2
Q

During exposure, the Cathode has a what type of potential?

A

Large Negative Potential

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3
Q

What material is the focusing cup made of?

A

Nickel
(has a high heat capacity)

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4
Q

What does the focusing cup do?

A

Focuses the Space Cloud

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5
Q

What kind of charge does the focusing cup possess?

A

Low negative charge

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6
Q

Why are the tungsten filaments coated in thorium?

A

Thorium allows for a more efficient thermionic emission process by burning off 2% more electrons.

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7
Q

What is thermionic emission?

A

The process of burning off electrons

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8
Q

What forms the focused electron cloud (space cloud)?

A

Thermionic emission

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9
Q

What type of energy does the space cloud possess?

A

Potential Energy

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10
Q

What is potential energy?

A
  • Energy at rest.
  • Ability to do work by virtue of position.
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11
Q

What is kinetic energy?

A
  • Energy in motion
  • Possessed by all matter in motion
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12
Q

Incident electrons moving toward the anode possess what type of energy?

A

Kinetic Energy

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13
Q

When the electrons hit the heavy metal atoms of the target, what happens to their kinetic energy?

A

Their kinetic energy is transferred to the target atoms.

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14
Q

What percentage of kinetic energy is turned into heat?

A

99.8%

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15
Q

What percentage of kinetic energy is turned into useful x-rays?

A

Less than 1%

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16
Q

What is the distance between the target and the filament?

A

1cm

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17
Q

What is the measure of the maximum electrical potential across an x-ray tube?

A

kVp

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18
Q

Potential Difference
Electromotive Force
Voltage

A

Different terms for kVp

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19
Q

When is kVp applied to the tube?

A

When the exposure button is pressed.

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20
Q

Does kVp control the temperature of the filament?

A

No

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21
Q

Does kVp control how many electrons are in the focusing cup?

A

No

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22
Q

Does kVp control how many electrons cross the tube?

A

No

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23
Q

kVp does not create a larger x-ray beam because more electrons are burned off.

A

kVp does not create a larger x-ray beam because more electrons are burned off.

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24
Q

When the exposure button is pressed, how does this affect the anode and cathode?

A

The anode becomes positively charged and the cathode becomes negatively charged.

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25
Q

Most radiographs use what range of kVp techniques?

A

50-120 kVp

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26
Q

How many volts is 1 kVp?

A

1,000 volts = 1 kVp

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27
Q

When kVp is increased, more electrons become attracted to the anode, which _____ the quantity of x-rays in the beam.

A

Increases

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28
Q

What increases the probability that all available electrons in the space charge will be attracted to the anode?

A

Increasing kVp

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29
Q

Increasing the kVp, results in the electrons possessing a greater kinetic energy when traveling from the cathode to the anode, this will make for a higher _______ beam.

A

Quality (penetrating)

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30
Q

What is it called when all possible electrons are attracted to the target?

A

Saturation Current

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31
Q

Does increasing kVp make x-ray photon production more efficient or inefficient?

A

More efficient

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32
Q

Does tube current have an effect on the efficiency of x-ray photon production?

A

No

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33
Q

mAs controls ____

A

Quantity

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34
Q

What is selected by the tech as the maximum voltage of a photon beam during an x-ray exposure?

(kVp vs. keV)

A

kVp

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35
Q

X-ray tube voltage describes ___?

(kVp vs. keV)

A

kVp

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36
Q

X-ray tube potential between the cathode to the anode describes ___?

(kVp vs. keV)

A

kVp

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37
Q

What does the unit eV describe?

A

The kinetic energy of the electrons in the x-ray tube and the photons produced at the target.

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38
Q

What determines the top keV value of the incident electron or x-ray photon produced?

A

kVp

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39
Q

What describes how fast an object is traveling?

A

Velocity

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40
Q

How fast are the electrons traveling from the cathode to the anode?

A

at half the speed of light

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41
Q

Tube voltage is expressed in ___?

A

kVp

42
Q

Tube current is expressed in __?

A

mA

43
Q

What is the tube current determined by?

A

The number of electrons emitted by the filament during thermionic emission.

44
Q

Apply kVp (potential difference) to the x-ray tube converts the ______ energy of the electron cloud into ______ energy of the electrons in motion.

A

Apply kVp (potential difference) to the x-ray tube converts the POTENTIAL energy of the electron cloud into KINETIC energy of the electrons in motion.

45
Q

X-ray photon production follows the acceleration of electrons.

A

X-ray photon production follows the acceleration of electrons.

46
Q

When an electron is slowed down as it interacts with the anode, describes which type of electron target interaction?

A

Electron Deceleration

46
Q

What are the two types of electron target interactions?

A

Electron Deceleration
Electron Ionization

47
Q

With electron deceleration, when is the x-ray photon produced?

A

When the electron is slowed down

48
Q

What type of x-rays (Bremsstrahlung or Characteristic) are produced with electron deceleration?

A

Bremsstrahlung X-rays

49
Q

When an incident electron ionizes an atom of the target material, which type of electron target interaction is this?

A

Electron Ionization

50
Q

What term means to remove an electron from an atom of tungsten?

A

Ionize

51
Q

With electron ionization, when is the x-ray photon produced?

A

When the cascading effect takes place.

52
Q

What type of x-rays (Bremsstrahlung or Characteristic) are produced with electron ionization?

A

Characteristic

53
Q

What does the term Bremsstrahlung mean?

A

“Slowed Down Radiation”
or
“Braking Radiation”

54
Q

When are Bremsstrahlung x-rays produced?

A

When the high-speed electrons incident from the cathode interact with the NUCLEUS of a tungsten atom.

55
Q

Bremsstrahlung x-rays vary from low energy (keV) x-rays to the peak energy (keV) of the kVp selected on the control panel.

A

Bremsstrahlung x-rays vary from low energy (keV) x-rays to the peak energy (keV) of the kVp selected on the control panel.

56
Q

What percentage of the primary beam is made up of Bremsstrahlung x-rays?

A

90%

57
Q

What charge does the nucleus of a tungsten atom possess?

A

Positive charge

58
Q

A car turns a corner at a high speed and veers off of its original trajectory. A portion of the energy that was contained in the kinetic energy of the tire is transferred into heat, making a “skid mark”. The tire retains the rest of the energy as it turns the corner.

Referring to this example, the original kinetic energy of the tire is equivalent to___?

A

Original kinetic energy of the incident electron

59
Q

A car turns a corner at a high speed and veers off of its original trajectory. A portion of the energy that was contained in the kinetic energy of the tire is transferred into heat, making a “skid mark”. The tire retains the rest of the energy as it turns the corner.

Referring to this example, the energy of the skid mark is equivalent to __?

A

The energy spent to create an x-ray photon from the electron being forced to slow down.

60
Q

A car turns a corner at a high speed and veers off of its original trajectory. A portion of the energy that was contained in the kinetic energy of the tire is transferred into heat, making a “skid mark”. The tire retains the rest of the energy as it turns the corner.

Referring to this example, the final kinetic energy of the tire after turning is equivalent to ____?

A

The final kinetic energy of the incident electron after turning towards the nucleus.

61
Q

Law of Conservation of Energy (Brems)

A

Original keV of the incident electron = keV of Bremsstrahlung x-ray photon + keV of the electron after nucleus influence

62
Q

A sharper turn around the nucleus results in a higher or lower energy photon?

A

Higher

63
Q

If kVp increases, Quality and Penetration ______

A

Increase

64
Q

Two variables determining x-ray keV

A

Proximity to nucleus
Original kVp setting

65
Q

In the diagnostic range, which type of x-rays are majority of the primary beam?

A

Bremsstrahlung

66
Q

Which type of x-ray production is responsible for the polyenergetic nature of the x-ray beam?

A

Bremsstrahlung

67
Q

Do very low energy (keV) x-rays contribute anything to the image?

A

No, just the patient’s dose.

68
Q

How are low energy Bremsstrahlung x-rays that don’t contribute to diagnostic radiographs dealt with?

A

Filtration

69
Q

Filtration creates a more _______ beam.

A

Monoenergetic

70
Q

If filtration is increased, the average quality of the x-ray beam is increased, and intensity is ______.

A

Decreased

71
Q

All atoms are comprised of a nucleus surrounded by shells that contains _____.

A

Electrons

72
Q

What does the nucleus contain?

A

The atom’s protons and neutrons

73
Q

What determines the atomic number of the atom?

A

The number of protons

74
Q

An atom contains the same number of protons and electrons until it loses or gains an electron. What process is this?

A

Atom Ionization

75
Q

An incident electron must contain at least __ keV in order to collide with and remove a K-shell electron from a tungsten atom.

A

69 keV

76
Q

When the cathode electron ionizes a target atom by removing a K-shell electron, a temporary electron void is produced at the K-shell. The outermost shell then falls into the void of the K-Shell. What is this called?

A

Cascading Effect

77
Q

The transition of an orbital electron from an outer shell to an inner shell is accompanied by the emission of ______

A

an X-ray

78
Q

The outer shell electron drops into the inner shell electron to fill the void left by ionization, results in a _______ photon.

A

Characteristic photon

79
Q

K-shell keV value

A

69 keV

80
Q

L-shell keV value

A

12 keV

81
Q

The energy of x-rays created by the K-shell will always be _____

A

57 keV

82
Q

What makes up the discrete portion of the beam?

A

Characteristic X-rays

83
Q

What percentage of the primary useful beam is Characteristic X-rays?

A

10%

84
Q

At 70 kVp, the percentage of characteristic x-rays in the primary beam is ___

A

10%

85
Q

At 100 kVp, the percentage of characteristic x-rays in the primary beam will increase to ___

A

15%

86
Q

How are Characteristic x-rays better than Bremsstrahlung x-rays?

A

They aren’t

87
Q

Which type of x-ray production is responsible for the monoenergetic energies of the x-ray beam?

A

Characteristic X-rays

88
Q

How would you move the discrete portion (“the line”) in the beam?

A

Changing the material.
Not by changing kVp.

89
Q

Which side of the tube has a greater number of photons?

A

Cathode

90
Q

A radiographic phenomenon affecting the intensity of the x-ray beam.

A

Anode Heel Effect

91
Q

Due to the angle of the anode, a greater number of incident x-ray photons will be produced at _____

A

The cathode side of the tube

92
Q

Three variables affecting Anode Heel Effect

A

1) SID
2)Anode Target Angle
3) Image Field Size

93
Q

What kind of relationship do SID and Anode Heel Effect have?

A

Indirect

94
Q

What kind of relationship do Field Size and Anode Heel Effect have?

A

Direct

95
Q

What kind of relationship do Anode Target Angle and Anode Heel Effect have?

A

Indirect

96
Q

A smaller angle results in a _______ image.

A

Sharper

97
Q

“FAT-CAT”

A

The thicker part goes under the cathode side of the tube.

98
Q

Examples of FAT-CAT

A

Femur
Lower Leg
Humerus
T-Spine
L-Spine

99
Q

Beam Intensity

A

Quantity of x-ray photons within the beam

100
Q

Exit Beam

A

When the beam exits the pt. and hits the IR

RAD1418 (5 decks)

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