X-Ray Machine Flashcards

1
Q

Where x-rays are produced

A

X-ray tube

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2
Q

Evacuated glass bulbs with positive and negative electrodes

A

X-ray tubes

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3
Q

X-ray tubes are special types of — which are electronic tube with 2 electrodes (+,-)

A

diode

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4
Q

The x-ray tube consists of a (1) and (2) embossed wtithin an envelope and then enclosed in a (3)

A
  1. cathode
  2. anode
  3. protective housing
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5
Q

X-rays emitted through the window of the tube

A

Useful beam

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6
Q

X-rays that escape from the protective housing (extra radiation)

A

Leakage radiation

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7
Q

2 Funtions of the diala oil

A
  1. Insulator against electric shock
  2. Thermal cushion to dissipate heat
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8
Q

External components of the x-ray machine

A
  1. Protective housing
  2. Glass/metal enclosure /envelope
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9
Q

Guards tagainst excessive radiation exposure

A

Protective housing

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10
Q

Incorporates specially designed high-voltge receptacle to protect against electric shock (to prevent electrocution

A

Protective housing

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11
Q

Provides mechanical support and protects the tube from damage caused by rough handling

A

Protective housing

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12
Q

Mainstains vacuum inside the tube

A

Glass/ metal enclosure/envelope

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13
Q

Early x-ray tube

A

Crookes tube

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14
Q

Modern x-ray tube

A

Coolidge tube

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15
Q

Differentiate crookes tube and coolidge tube

A

The crookes tube is an early x-ray tube, but is not a vaccum tube. Rather, it contained controlle quantites of gas.

The coolidge tube on the other hand, is a modern x-ray tube which is a vaccum tube.

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16
Q

What is the glass ecnlosure made up of?

A

Pyrex glass

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17
Q

As it ages, it causes arcing and tube failure

A

Glass enclosure

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18
Q

As the glass enclosure ages, what does it cause?

A

arcing and tube failure

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19
Q

It maintains constant electric potential between the electrons of the tube current and enclosure

A

Metal enclosure

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20
Q

An x-ray enclosure that has a longer life and is less likely to fail

A

Metal enclosure

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21
Q

The metal enclosur emaintains constant (1) between the electrons of the (2) and (3)

A
  1. electric potential
  2. tube current
  3. enclosure
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22
Q

Are of glass or metal enclosure

A

Window

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23
Q

Why is the x-ray tube’s window thin?

A

To allow maximum emission of x-rays

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24
Q

Internal components of the x-ray tube

A
  1. Cathode
  2. Anode
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25
Q

Negative side of the tube

A

Cathode

26
Q

2 primary parts of the cathode

A
  1. Filament
  2. Focusing cup
27
Q

3 Functions of the Cathode

A
  1. Produce thermionic cloud
  2. Conduct high voltage to the gap between cathode and anode
  3. Focus the electron stram as it heads for the anode
28
Q

Small coil of thin thoriated tungsten wire

A

Filament

29
Q

Thickness and length of the filament

A

0.1-0.2 mm thick;
1-2 cm long, 2mm diameter

30
Q

When heated, this emits electrons

A

Filament

31
Q

When the current through the filament is sufficiently high, the outer shell electron of the filament atom are (1) and (2) from the filament — (3)

A
  1. “boiled off”
  2. ejected
  3. thermionic emission
32
Q

Required temperature for thermionic emission to take place

A

2, 200° C

33
Q

The filament is a small coil of thin — wire

A

thoriated tungsten

34
Q

Shallow depression in the cathode assemblyl assigned to house the filment

A

Focusing cup

35
Q

It’s purpose is to narrow the thermionic cloud as it is driven toward the anode

A

Focusing cup

36
Q

What is the focusing cup made out of

A

Nickel

37
Q

Negatively charged to electrostatically confine the electron beam to a small area of the anode

A

Focusing cup

38
Q

Positive side of the tube

A

Anode

39
Q

3 Fuctions of the anode

A
  1. Serves as a target surface for the hig-voltage electron from the filament (source of x-rays)
  2. Conducts high voltage from the cathode back into the x-ray generator circuitry
  3. Serves as primary thermal conductor
40
Q

2 Types of Anode

A
  1. Stationary Anode X-ray Tube
  2. Rotating Anode X-ray TUbe
41
Q

Where are stationary and rotating x-ray tube usually used?

A

Stationary: dental and portable x-ray
Rotating: general x-ray

42
Q

Area of anode struck by the electrons from the cathode

A

Target

43
Q

3 other terms for the target

A
  1. Focal spot
  2. Focal point
  3. Focal track
44
Q

The stationary target consists of (1) embedded in a (2) angled end of (3)

A
  1. rhenium-alloyed tungsten
  2. 45°
  3. copper rod
45
Q

Rotating target: Entire rotating disk which has a dimension of (1) is the target (made up of [2])

A
  1. 5-13cm
  2. tunsten alloy
46
Q

High capacity x-ray tubes have (1) or (2) layered under the

A
  1. molybdenum
  2. graphite
47
Q

What is the material of choice for the target for general rafiography, and give 3 reasons why

A

TUNGSTEN
1. Atomic number
2. Thermal conductivity
3. High meting point

48
Q

Tungsten meting point

A

3,410°C

49
Q

Differentiate the copper block from the anode stem

A

Copper block is stationary and is made up of copper. Anode is rotating and is made up of molybdenum.

50
Q

Mechanically supports the tungsten target and removes heat efficiently from the tungsten target due to its high heat conductivity

A

Copper block

51
Q

The shaft between the anode and rotor

A

Anode stem

52
Q

Why is the anode stem so narrow?

A

So as to reduce thermal conductivity

53
Q

Normal x-ray tubes rotate (1) rpm (revolutions per minute)

While high capacity machines can reach up to (2) rpm

A
  1. 3,400
  2. 10,000
54
Q

Used to turn the anode

A

Induction motor (rotating)

55
Q

2 components of the induction motor

A
  1. Stator
  2. Rotor
56
Q

A series of electromagnets equally spaces around the neck of the tube

A

Stator

57
Q

Differentiate the stator and rotor on the induction motor in terms of where they can be seen

A

The stator is a part outside of the glass/ metal enclosure while the rotor is a part inside of the galss/ metal enclosure

58
Q

Shaft made up of bars of copper and soft iron fabricated in one mass

A

Rotor

59
Q

What is the rotor made up of?

A

bars of copper and soft iron

60
Q

Copper and soft iron are — whic hmeans they are attracted to magnet

A

Ferromagnetic

61
Q

HEAT DISSIPATION

The purpose of the stem is to (1) the heat out of the x-ray tube. This is different compared to the roating anode which (2) radiates away the heat through the (3). The stationary anode will conduct the heat out of the tube to the (3).

A
  1. conduct
  2. radiates away
  3. surroundign oil