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Radiologic Exposures > Final Review (history and xray tube) > Flashcards

Final Review (history and xray tube) Flashcards

1
Q

Who were xrays discovered by?

A

Wilhelm Conrad

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2
Q

When were xrays discovered?

A

November 8, 1895

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3
Q

What was the first xray?

A

Roentgens wife’s hand

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4
Q

Who was the first fatality from xrays?

A

Clarence Dally

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5
Q

Who won the first Nobel prize presented for physics in 1901?

A

Roentgen

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6
Q

Who devised a fluoroscope using a fluorescing screen

A

Thomas Edison

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7
Q

Who improved crookes tube?

A

William Coolidge

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8
Q

what are the 3 Cardinal Rules of Radiation Protection?

A

Time, Distance, Shielding

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9
Q

What was designed in order to prevent radiation injury and effects?

A

-Cardinal Rules (time, distance, shielding)
-lead protective apparel worn by all radiation workers
-Radiation dose monitored through the use of a dosimeter

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10
Q

Four things that are needed for the production of xrays?

A

-Source of electrons (cathode filament)
- Target (tungsten anode)
-High voltage
-vacuum

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11
Q

A form of electromagnetic radiation

A

Xrays as energy

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12
Q

Behave both like waves and like particles

A

Xrays as energy

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13
Q

Move in waves that have wavelength and frequency

A

Xrays as energy

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14
Q

Wavelength and frequency are inversely related

A

Xrays as energy

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15
Q

Xrays also behave like particles and move as photons

A

Xrays as energy

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16
Q

What are some properties of xrays?

A

-xrays are invisible
-xrays are electrically neutral
-Xrays have no mass
-Xrays travel at the speed of light in a vacuum
-Xrays cannot be optically focused
-Xrays form a polyenergetic or heterogeneous beam
-Xrays can be produced in a range of energies
-Xrays travel in straight lines
- Xrays can cause some substances to fluoresce
-Xrays cause chemical changes to occur in radiographic and photographic film
-Xrays can penetrate the human body
-Xrays can be absorbed or scattered by tissues in the human body
- Xrays can produce secondary radiation
-Xrays can cause chemical and biologic damage to living tissue

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17
Q

Xray prodcution

A

-The production of xrays require a rapidly moving stream of electrons that are suddenly decelerated or stopped.
-The negative
electrode (cathode) is
heated, and electrons
bare emitted
(thermionic emission)
- The electrons are
attracted to the anode,
move rapidly towards
the positive electrode
and are stopped or
decelerated.

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18
Q

Protects against leakage radiation and electric shock

A

Tube housing

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19
Q

-metal or glass envelope
-negatively charged electrode
-positively charged electrode

A

Xray tube housing

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20
Q

What is part of the cathode?

A

Filament and focusing cup

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21
Q

Cathode assembly

A

Filament (coiled tungsten wire helix)
Focusing cup
associated wiring
low voltage side of xray circuit
Source of electrons

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22
Q

What types of coiled tungsten wire is there?

A

wire filament for large and small focal spot

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23
Q

What charge is the cathode?

A

Negative

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24
Q

What charge is the anode?

A

Positive

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25
Q

What kind of material is the filament made of?

A

Thoriated tungsten

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26
Q

What material is the focusing cup made of?

A

Nickel

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27
Q

May also be called the focal point, focal spot or the focal track?

A

Target

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28
Q

The process of boiling off electrons and produces a cloud of electrons by heating the filament

A

Thermionic emission

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29
Q

Dangers of Radiation

A

-Never stand in primary beam
-Collimating as small as you can
-Never hold patient
-Females 11-50 always shield

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30
Q

Occurs when no more electrons can be boiled off of the filament

A

Space charge effect

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31
Q

Is the primary thermal conductor of the tube

A

Anode

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32
Q

Three components of the anode

A

Anode, stator, and rotor

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33
Q

Why is tungsten used?

A

High melting point and difficult to vaporize

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34
Q

What are the two types of anods

A

Rotating and stationary

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35
Q

portion of the anode struck by the electrons

A

Target

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36
Q

What is the anode made up of

A

Tungsten Rhenium Alloys

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37
Q

What does it mean to have two filaments?

A

Dual Focus tube

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38
Q

Why does the xray tube need to be warmed up?

A

To prevent cracking and maintain vacuum

39
Q

Purpose of rotating anode

A

promote greater heat dissipation

40
Q

-Decelerates and stops electrons
-energy converted to heat and xrays
-Brems and characteristic interactions

A

Target

41
Q

What does a rotating anode require?

A

-requires a stator and rotor to rotate
-tungsten metal

42
Q

What determines the number of electrons boiled off

A

mA

43
Q

Atomic number of tungsten rhenium alloy

A

74

44
Q

Absorption of xrays produces in the tube by the anode, causes uneven distribution of xray intensity between the cathode and anode, more intensity of cathode side (fat cat)

A

Anode heel effect

45
Q

Area where electrons strike the anode

A

Focal Spot

46
Q

Leakage radiation Limit

A

100 milliroentgens per hour at 1 meter

47
Q

Physical area of the focal track being hit by the electrons

A

Actual focal spot

48
Q

What is the environment inside the xray tube once all air has been removed

A

Vacuum

49
Q

Tube failure

A

-Tube arcing (vaporized tungsten collection on envelope)
-filament breakage (“boost” and hold)

50
Q

-Filament heated
-causes electrons to be released from filament
-similar to filament heating in an incandescent lightbulb
-cathode filament is in a low temperature, pre-heat mode until xray exposure is initiated

A

Thermionic Emission

51
Q

Xray tube efficiency

A

1% xray
99%heat

52
Q

is housed in focusing cup and produces electrons to produce image

A

filament

53
Q

Three functions of the anode:

A

-Target surface for xray production
-Conducts high voltage
-serves as primary thermal conductor

54
Q

What changes the charge of the focusing cup from negative to positive

A

Grid Biased Tubes

55
Q

Necessary qualities of the anode

A

High atomic number
high melting point
high heat conduction ability

56
Q

Heat tolerant pyrex glass or metal

A

Envelope

57
Q

What do the electrons become when they hit the anode

A

photons

58
Q

What two things control the size of the effective focal spot

A

Size of the focal spot and anode target angle

59
Q

-assists with heat loading
-backed with molybdenum and/or graphite
-backing acts as “heat sink”
-Increases xray tube thermal capacity

A

Anode layering

60
Q

-space charge effect
-compresses thermionic cloud
-concentrate the electron beam towards the focal spot of the anode

A

Focusing cup

61
Q

What is the anode made up of?

A

Tungsten rhenium alloy

62
Q

-made of molybdenum
-connects the anode to the rotor

A

Stem

63
Q

What is the line focus principle

A

Spreads heat over a greater area of the anode and allows the effective focal spot to be smaller than the actual focal spot

64
Q

What is the purpose of the glass envelop

A

Absorbs xrays and ensures a vacuum

65
Q

Purpose of the focusing cup

A

To group the electrons for their passage to the anode

66
Q

Why do we follow the warm up procedure?

A

To prevent the tube from cracking and to maintain vacuum

67
Q

A molybdenum shaft is used to connect the anode to the rotor because

A

It is a less dense metal with a high melting point that helps anode to spin faster

68
Q

What does “pitting” mean

A

Holes on the focal track

69
Q

Portion of anode that electron stream contacts

A

Target Area

70
Q

Purpose of the fan in the tube housing is to

A

Promote heat dissipations

71
Q

Average anode rotation speeds in diagnostic ray tubes are in the ranges of:

A

3,000-10,000

72
Q

The only thing located outside of the envelope that consists of copper windings

A

Stator

73
Q

Made of a copper cylinder in the step of the xray tube and is supported by the high strength ball bearings

A

Rotor

74
Q

What does the protective housing consist of ?

A

Metallic
supports xray tube
controls leakage and scatter radiation
prove mechanisms to cool tube

75
Q

How can we extend the life of the tube

A

-tube warm up
-avoid frequent “boosting”
-use low mA when possible
-use low speed rotation when possible
-follow rotating charts
-avoid rough handling
-listen to unusual sounds

76
Q

What is off focus radiation

A

Undesirable part of the beam, not hitting anode, low energy and no diagnostic value, produces “ghosting”

77
Q

What does xray stand for

A

the X in xray means unknown

78
Q

What is the divergence of the beam

A

Energy that is coming out and whats interacting with the patient

79
Q

Compare and contrast actual focal spot and effective focal spot

A

Actual focal spot is the area being hit by electrons and effective focal spot is projected area of xray beam.
Effective focal spot should be smaller.
A before E

80
Q

results in suboptimum anode rotation speed

A

stator failure

81
Q

True or False
Xrays are invisible

A

true

82
Q

True or false
Xrays can travel around corners

A

False

83
Q

Sequence of taking xrays

A
  1. Current runs through the filament circuit
  2. Filament gets hot
  3. Filament glows
  4. Filament boils of electrons
  5. Electrons form a space cloud
  6. Electrons are repelled from the focusing cup
  7. Electrons are attracted by the anode
  8. Electrons move over to the anode
  9. Electrons slam into the anode at the target
  10. Electrons lose energy
  11. Light, heat and X-rays are produced
  12. Focal spot is formed
  13. X-rays are emitted isotropically
  14. X-rays are absorbed by the glass and metal housing
84
Q

What helps the stator to rotate properly

A

Ballbearings

85
Q

-Ferromagnetic bars arranged in cylindrical pattern
-inside xray tube glass envelope
-copper cylinder connected to anode disk by molybdenum stem
-turns when stator is energized

A

Rotor

86
Q

what type of body parts would the large filament focus on

A

large focusing body parts (more heat)

87
Q

what does the filament length and width impact

A

recorded detail or special resolution

88
Q

Typically controlled by the xray circuitry and wont go higher than what is already set

A

Saturation Current

89
Q

-Heat tolerant pyrex glass or metal
-Two functions: supports anode/cathode assemblies and maintain a vacuum
-modern tubes now metal

A

Envelope

90
Q

Near perfect and critical to efficient xray productions

A

vacuum

91
Q

Protective housing provides mechanisms to cool tube

A

-cooling oil surrounding tube
-cooling fans
-water cooling in high end tube designs

92
Q

-metallic
-supports xray tube
-controls leakage and scatter radiation(lead lined)
-provides mechanisms to cool tube

A

Protective housing

93
Q

Be able to label xray tube

A
94
Q
A

Radiologic Exposures (11 decks)

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