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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
The housing controls the ___ and __ , isolates the ___ and provides a means to ____ the tube
Leakage and scatter radiation High voltage Cool
25
Any photons that escape from the housing except at the port
Leakage radiation
26
Leakage radiation must not exceed ___ at ____
100 mR/hr at 1 meter
27
The ___ also provide mechanical support and protection from damage
Housing
28
The housing also contains ___ that provides more insulation and a thermal cushion
Oil
29
Some housing have ___ for cooling
Fan
30
The housing incorporates specially designed high voltage receptors to protect against ___
Electric shock
31
Glass enclosure is made of ___ to enable it to withstand the tremendous heat generated
Pyrex glass
32
The window is a ____ with thin section of glass where the useful bean is emitted
5 cm2
33
___ allows for more efficient production of x-ray and longer tube life
Vacuum
34
With the presence of air,
Electron flow from cathode is reduced Fewer x-ray are produced More heat are generated
35
Improvement in design incorporates metal rather than glass as part or all of the enclosure
Metal enclosure
36
___ tubes maintain a constant electric potential between the electrons of the tube current and the enclosure
Metal enclosure
37
They have longer life and less likely to fail
Metal enclosure
38
All high-capacity x-ray tubes now use ___
Metal enclosure
39
Cathode is negative side of the tube and contains two primary parts
Filaments Focusing cup
40
Is a coil of wire with approx 2mm in diameter and 1-3 cm long
Filament
41
It emits electrons when heated
Filament
42
Filaments are made of __
Thoriated tungsten
43
Melting point of tungsten
3410*C
44
Add of 1-2% of ___ prolong tube life and efficiency of thermionic emession
Thorium
45
Most rotating anode x ray tubes have 2 filaments
Dual focus filament
46
Either filament can be used for lower mA station approx
300 mA or less *dual focus filaments
47
Desposition on the inside of glass enclosure is the most common cause of tube failure
Tungsten vaporization
48
A shallow depression in the cathode assembly designed to house the filament
Focusing cup
49
It is a metal shroud that surrounds the filament
Focusing cup
50
The focusing cup has ___ charge
Negative
51
The effectiveness of focusing cup is determined by the ff:
Its size and shape Its charge Filament size and shape Position of the filament in the focusing cup
52
X- ray tube current is adjusted by controlling the ___
Filament current
53
Emmision of electron from heated surface
Thermionic emission
54
Also known as thermal electron emission
Thermionic emission
55
Process by which charge carriers such are electrons or ions move over a surface by induction of heat
Thermionic emission
56
Formation of electron cloud near filament
Space charge
57
As kVp increases a greater percentage of thermionically emitted electrons are driven toward the anode
Saturation current
58
Thermionic emission at low kVp and high mA can be ___
Space charge
59
Consist of anode stator and rotor
Anode assembly
60
Positive aide of the tube
Anode
61
Functions of anode
Electrical conductor Provides Mechanical support Thermal dissipator
62
Anode materials
Copper Molybdenum Graphite
63
It conducts electricity and radiates heat and contains the target
Anode
64
X ray tube classified by type of anode
Rotating Stationary
65
Use in dental x ray imaging system, some portable imaging system w/ch high tube current and power are not required
Stationary anode x ray tube
66
The must be capable of producing high intensity x ray beams in short time
Rotating anode x ray tube
67
Allows the electron beam to interact with a much larger target area
Rotating anode
68
The heat is not confined to small area
Rotating anode
69
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 ___
Graphite Tungsten-rhenium alloy Molybdenum
70
Area of anode stuck by the electrons from the cathode
Target
71
In rotating anode the entire rotating disc is the ___
Target
72
Target material Stationary anode ___ Rotating anode ___
Tungsten alloy embedded in copper anode Tungsten (W) with rhenium
73
High capacity tubes have ___ or ___ under the tungsten target thus making the anode lighter and easier to rotate
Molybdenum Graphite
74
Reasons why tungsten is material of choice
Atomic number Thermal conductivity High melting point
75
Measure of the ability of substance to conduct heat
Thermal conductivity
76
Melting point of tungsten
3,422*c or 6,192*f
77
A form of extremely localize corrosion that leads to creation of small holes in the metal
Pitting corrosion
78
Actual target for stationary tube is 4mm2
Target area
79
Total target area of the rotating anode is 1,760 mm2
Target area
80
Most rotating anodes revolve at 3600 rpm
Rotating anode
81
Anode of high capacity tubes rotate at up to 10,000 rpm
Rotating anode
82
Shaft between the anode and the rotor
Anode stem
83
Sten is usually made of molybdenum because it is a poor heat conductor
Anode stem

Mid Terms X-ray Tube (1 decks)

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