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Mid Terms X-ray Tube > Historical Perspective > Flashcards

Historical Perspective Flashcards

0
Q

Dr. Roentgen used ____ to make the first x-ray

A

Crookes-Hittorf

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1
Q

Demonstration by crookes that cathode rays travel in straight lines

A

Cathode
Aluminum cross and anode
Fluorescent image
Dark shadow

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2
Q

There was no ____ so x-rays were emitted in ____ directions

A

Shielding

Direction

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3
Q

The ____ tube was a major advancement in tube design

A

Coolidge Hot cathode

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4
Q

It is a component of x-ray imaging system rarely seen by radiologic technologist

A

X-ray tube

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5
Q

Modern x-ray tube and coolidge tube is _____ tube

A

Vacuum tube

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6
Q

It contains 2 electrodes

A

Anode

Cathode

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7
Q

__ to __ cm long and __ cm in diameter

A

30 to 50 cm

20 cm

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8
Q

2 principal parts

A

Rotating (anode)

Cathode

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9
Q

Both anode and cathode are

A

Electrodes

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10
Q

Any tube that has two electrodes is called a

A

Diode

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11
Q

Self-rectification highest limits are about ___

A

30 mA at 90 kV

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12
Q

Overstepping these bounds can cause temperature rise in the anode target yo the point of

A

Thermionic emission

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13
Q

External parts of x-ray tube

A

Support structure

Protective housing

Glass or metal enclosure

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14
Q

Internal structures

A

Anode

Cathode

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15
Q

Three main methods of x-ray tube support

A

Ceiling support system

Floor to ceiling support system

C-arm support system

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16
Q

The most frequently used support system

A

Ceiling support system

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17
Q

Consist of two perpendicular sets of ceiling-mounted rails

A

Ceiling support system

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18
Q

This allows for longitudinal and transverse travel of x-ray tube

A

Ceiling support system

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19
Q

Had a single column with rollers at each end one attached to the ceiling mounted rail and the other attached to the floor mounted rail

A

Floor to ceiling support system

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20
Q

These system are ceiling-mounted and provide for very flexible x-ray tube positioning

A

C-arm support system

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21
Q

The tube is housed in a lead line metal

A

Protective housing

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22
Q

The x-ray photons are generated

A

Isotropically or in all directions

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23
Q

The housing is designed to ____

A

Limit the beam to window

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24
Q

The housing controls the ___ and __ , isolates the ___ and provides a means to ____ the tube

A

Leakage and scatter radiation

High voltage

Cool

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25
Q

Any photons that escape from the housing except at the port

A

Leakage radiation

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26
Q

Leakage radiation must not exceed ___ at ____

A

100 mR/hr at 1 meter

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27
Q

The ___ also provide mechanical support and protection from damage

A

Housing

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28
Q

The housing also contains ___ that provides more insulation and a thermal cushion

A

Oil

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29
Q

Some housing have ___ for cooling

A

Fan

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30
Q

The housing incorporates specially designed high voltage receptors to protect against ___

A

Electric shock

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31
Q

Glass enclosure is made of ___ to enable it to withstand the tremendous heat generated

A

Pyrex glass

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32
Q

The window is a ____ with thin section of glass where the useful bean is emitted

A

5 cm2

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33
Q

___ allows for more efficient production of x-ray and longer tube life

A

Vacuum

34
Q

With the presence of air,

A

Electron flow from cathode is reduced

Fewer x-ray are produced

More heat are generated

35
Q

Improvement in design incorporates metal rather than glass as part or all of the enclosure

A

Metal enclosure

36
Q

___ tubes maintain a constant electric potential between the electrons of the tube current and the enclosure

A

Metal enclosure

37
Q

They have longer life and less likely to fail

A

Metal enclosure

38
Q

All high-capacity x-ray tubes now use ___

A

Metal enclosure

39
Q

Cathode is negative side of the tube and contains two primary parts

A

Filaments

Focusing cup

40
Q

Is a coil of wire with approx 2mm in diameter and 1-3 cm long

A

Filament

41
Q

It emits electrons when heated

A

Filament

42
Q

Filaments are made of __

A

Thoriated tungsten

43
Q

Melting point of tungsten

A

3410*C

44
Q

Add of 1-2% of ___ prolong tube life and efficiency of thermionic emession

A

Thorium

45
Q

Most rotating anode x ray tubes have 2 filaments

A

Dual focus filament

46
Q

Either filament can be used for lower mA station approx

A

300 mA or less

*dual focus filaments

47
Q

Desposition on the inside of glass enclosure is the most common cause of tube failure

A

Tungsten vaporization

48
Q

A shallow depression in the cathode assembly designed to house the filament

A

Focusing cup

49
Q

It is a metal shroud that surrounds the filament

A

Focusing cup

50
Q

The focusing cup has ___ charge

A

Negative

51
Q

The effectiveness of focusing cup is determined by the ff:

A

Its size and shape

Its charge

Filament size and shape

Position of the filament in the focusing cup

52
Q

X- ray tube current is adjusted by controlling the ___

A

Filament current

53
Q

Emmision of electron from heated surface

A

Thermionic emission

54
Q

Also known as thermal electron emission

A

Thermionic emission

55
Q

Process by which charge carriers such are electrons or ions move over a surface by induction of heat

A

Thermionic emission

56
Q

Formation of electron cloud near filament

A

Space charge

57
Q

As kVp increases a greater percentage of thermionically emitted electrons are driven toward the anode

A

Saturation current

58
Q

Thermionic emission at low kVp and high mA can be ___

A

Space charge

59
Q

Consist of anode stator and rotor

A

Anode assembly

60
Q

Positive aide of the tube

A

Anode

61
Q

Functions of anode

A

Electrical conductor

Provides
Mechanical support
Thermal dissipator

62
Q

Anode materials

A

Copper

Molybdenum

Graphite

63
Q

It conducts electricity and radiates heat and contains the target

A

Anode

64
Q

X ray tube classified by type of anode

A

Rotating

Stationary

65
Q

Use in dental x ray imaging system, some portable imaging system w/ch high tube current and power are not required

A

Stationary anode x ray tube

66
Q

The must be capable of producing high intensity x ray beams in short time

A

Rotating anode x ray tube

67
Q

Allows the electron beam to interact with a much larger target area

A

Rotating anode

68
Q

The heat is not confined to small area

A

Rotating anode

69
Q

Construction of a rotating anonde

Base is made of ___ for a solid base

Target is made of ___

Parts of holding the target are made of ___

A

Graphite

Tungsten-rhenium alloy

Molybdenum

70
Q

Area of anode stuck by the electrons from the cathode

A

Target

71
Q

In rotating anode the entire rotating disc is the ___

A

Target

72
Q

Target material

Stationary anode ___

Rotating anode ___

A

Tungsten alloy embedded in copper anode

Tungsten (W) with rhenium

73
Q

High capacity tubes have ___ or ___ under the tungsten target thus making the anode lighter and easier to rotate

A

Molybdenum

Graphite

74
Q

Reasons why tungsten is material of choice

A

Atomic number

Thermal conductivity

High melting point

75
Q

Measure of the ability of substance to conduct heat

A

Thermal conductivity

76
Q

Melting point of tungsten

A

3,422c or 6,192f

77
Q

A form of extremely localize corrosion that leads to creation of small holes in the metal

A

Pitting corrosion

78
Q

Actual target for stationary tube is 4mm2

A

Target area

79
Q

Total target area of the rotating anode is 1,760 mm2

A

Target area

80
Q

Most rotating anodes revolve at 3600 rpm

A

Rotating anode

81
Q

Anode of high capacity tubes rotate at up to 10,000 rpm

A

Rotating anode

82
Q

Shaft between the anode and the rotor

A

Anode stem

83
Q

Sten is usually made of molybdenum because it is a poor heat conductor

A

Anode stem

Mid Terms X-ray Tube (1 decks)

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