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X-ray Physics > Test #1 > Flashcards

Test #1 Flashcards

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1
Q

When were X-rays discovered?

A

November 8th 1895

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2
Q

What type of tubes was Roentgen working with when he discovered xrays?

A

Vacuum tubes

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3
Q

X-rays are a type of electromagnetic radiation that acts like both _____ & _____

A

Waves; Particles

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4
Q

X-rays are described as the smallest units of electromagnetic radiation which is known as what?

A

Photons

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5
Q

This defines the penetrating power of any radiant energy & is the distance b/w 2 successive crests in the waveform

A

Wavelength

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6
Q

Represents the number of waves passing a given point per given unit of time

A

Frequency

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7
Q

What is the relationship b/w wavelength & frequency?

A

They are inversely proportional

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8
Q

What is the relationship b/w wavelength & penetrating power?

A

They are inversely proportional

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9
Q

What part of the x-ray machine are the x-rays produced?

A

The Tube

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10
Q

What are the 3 major parts of the x-ray tube?

A

Cathode
Anode
Glass Envelope

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11
Q

The glass envelope is made of what?

A

Pyrex

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12
Q

The glass envelope is a vacuum tube that allows for what?

A

Efficient x-ray production
Longer tube life
Less heat is produced
Faster electron flow

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13
Q

The protective housing is lined with what?

A

Lead

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14
Q

What are the functions of the protective housing?

A

Controls excess radiation exposure
Prevents electrical shock
Mechanical support for the tube

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15
Q

This is the negatively charged electrode in the tube

A

Cathode

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16
Q

What are the 2 major parts of the cathode?

A

Filament (source of electrons)

Focusing cup

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17
Q

What is the filament made of?

A

Tungsten

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18
Q

What is the M/C cause of tube failure?

A

Vaporization of the tungsten filament

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19
Q

Describe the 2 filament wires in a dual focus tube

A

Large filament produces a large focal spot size of approx. 1.0 or 1.2mm
Small filament produces a small focal spot size of approx. 0.5 or 0.6mm

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20
Q

This condenses & directs the electrons emitted from the filament toward the target. Focuses the beam on the actual focal spot

A

Focusing Cup

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21
Q

What is the focusing cup made of?

A

Nickel

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22
Q

This is the positively charged electrode in the tube

A

Anode

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23
Q

What is the primary component of the Anode?

A

Tungsten disc called the target

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24
Q

What are the 2 types of anodes?

A

Stationary - used in dental & portable xray machines

Rotating - utilized in most general purpose tubes

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25
Q

What are 2 advantages of rotating anodes?

A

Increase the surface area of the target

Spreads the heat over a larger area

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26
Q

What is the Target primarily made out of?

A

Tungsten

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27
Q

What part of the anode is struck by electrons from the cathode?

A

the Target

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28
Q

What part of the target gets bombarded by the electrons which are boiled off of the filament?

A

Focal Spot (source of radiation)

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29
Q

What serves to rotate the anode?

A

Induction motor

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30
Q

What are the magnets outside the glass envelope called?

A

Stator

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31
Q

What is the shaft of copper & iron inside the glass envelope that turns the target called?

A

Rotor

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32
Q

What are 6 characteristics of x-ray photons?

A

Possess no mass
Have no electrical charge
Travel at speed of light in a vacuum
Travel in straight lines
Make certain chemical compounds fluoresce
Can change biological matter via ionization

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33
Q

This occurs when the electron passes near the nucleus of the atom & the positive charge of the nucleus deflects the electron from its path

A

Braking (Bremsstrahlung) Radiation

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34
Q

Lost energy from braking radiation mostly becomes what?

A

Heat (99%)

35
Q

This occurs when the incident electron ejects an orbital electron from an inner shell of the atom. It leaves a hole and the atom becomes unstable, so an outer shell electron moves in to fill the hole. This results in the production of an x-ray photon.

A

Characteristic radiation

36
Q

Above 70kVp, what % of x-rays are braking radiation?

A

85% braking, 15% characteristic

37
Q

Below 70kVp, what % of x-rays are braking radiation?

A

100%

38
Q

Boiling electrons off of the filament is called what?

A

Thermionic Emission

39
Q

When the exposure button is pressed, what occurs on the cathode side?

A

Electrons move from cathode to anode (tube current)

40
Q

When electrons strike the target, what % of the kinetic energy is converted to heat?

A

99% heat, 1% x-rays

41
Q

The quantity of the x-ray beam indicates what?

A

Number of photons in the primary beam

42
Q

The quantity of electrons in the tube current & the quantity of x-rays produced are directly proportional to what?

A

The milliamperage

43
Q

The quality of the x-ray beam indicates what?

A

Its penetrating power (kVp)

44
Q

What determines the quality or energy of the x-rays that are produced?

A

Speed of the electrons

45
Q

Increasing the kVp increases what?

A

Speed of the electrons (increase penetrability & increase quantity)

46
Q

This determines the length of time that the tube current flows from the cathode to the anode (also the time that the x-ray tube produces x-rays)

A

Exposure time

47
Q

mA x time(s) =

A

mAs

48
Q

There is no effect of mAs on the ________ of x-rays produced

A

Quality

49
Q

What type of timer is the most accurate & most commonly used?

A

Electronic timers

50
Q

Sensor lies in the film holder, b/w the pt & the film & determines when enough radiation has gone through the pt to properly expose the film

A

Automatic Exposure Control

51
Q

The size of the area on the target is being exposed to electrons from the cathode

A

Actual Focal Spot Size

52
Q

What is the focal spot size directly under the target called?

A

Effective focal spot size

53
Q

The smaller the effective focal spot size, the better or worse the quality of the radiograph?

A

Better

54
Q

What is the Line Focus Principle?

A

As the target angle decrease, so does the effective focal spot size

55
Q

X-rays that are produced from the anode side of the target must go through a greater thickness of target material creating what effect?

A

Anode Heel Effect

56
Q

The x-ray beam that exits the tube housing to create the radiographic image is called what?

A

Primary x-ray beam

57
Q

Low energy photons do not contribute to the formation of the image, only to what?

A

patient dose

58
Q

A thin sheet of aluminum b/w the tube housing & the collimator is what type of filtration?

A

Added filtration

59
Q

Filtration that is permanently placed in the path of the beam. Glass envelope, oil, or mirror in the collimator.

A

Inherent Filtration

60
Q

Sum of the added & inherent filtration

A

Total filtration. Tubes that operate above 70 kVp must have a minimum of 2.5mm of aluminum equivalent total filtration

61
Q

These types of filters are attached to the outside of the tube housing to alter the intensity of the primary beam

A

Compensating filters

62
Q

What is the M/C type of compensating filter?

A

Wedge filter

63
Q

Indirect measurement of the total filtration in the path of the x-ray beam. Doesn’t directly measure the total amount of aluminum in the path of the beam

A

Half-Value Layer

64
Q

What are 3 types of transformers used in an x-ray generating system?

A

Step-up (high voltage) transformer
Step-down (filament) transformer
Autotransformer

65
Q

Which transformer supplies the tube w/ the high voltage necessary to operate?

A

Step-Up (high voltage) transformer

66
Q

Which transformer supplies the filament w/ the low voltage that it needs?

A

Step-Down (filament) Transformer

67
Q

This transformer allows for the selection of the voltage applied across the tube

A

Autotransformer

68
Q

This compensates for variations in the current coming in through the power lines that may not be consistent

A

Line compensator

69
Q

This controls the tube current

A

Milliampere selector (filament control)

70
Q

What is the max mA utilized w/ a small filament?

A

200mA

71
Q

This controls the penetrating power of the x-ray photons

A

kVp Selector

72
Q

This converts the low supply voltage into kilovoltage of the proper wave form

A

High voltage generator

73
Q

The process of converting AC current into DC current is called what?

A

Rectification

74
Q

Type of rectification where the inverse voltage is reversed, so that a positive voltage always flows across the tube. Seen in single phase x-ray machines

A

Full-wave Rectification

75
Q

Three phase x-ray machines are used primarily for what?

A

Special procedures (angiography)

76
Q

The device that receives the radiation that exits the pt.

A

Image receptor

77
Q

The process in which some of the x-ray beam will be absorbed in the tissue & some will pass through

A

Differential absorption

78
Q

The reduction in the energy of the primary beam as it passes through the body

A

Attenuation

79
Q

This is responsible for the total absorption of the incoming x-ray photon

A

Photoelectric effect

80
Q

Those x-ray photons that are not immediately absorbed by the tissues.

A

Scatter

81
Q

Electrons interact w/ outer shell electrons reducing the energy which is d/t the x-ray interaction w/ matter is known as what?

A

Compton Effect

82
Q

Substances that contain many hydrogen atoms have a higher probability of what b/c hydrogen has almost twice the number of electrons as most other substances

A

Compton Scatter

83
Q

What are the 3 fates of the scattered photon?

A

Strike the film
Absorb in the tissue
Leave the pt & not strike the film

X-ray Physics (4 decks)

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