Chapter 5 Exam Flashcards

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1
Q

Anode side is the _______ side of the tube

A

positive

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2
Q

Anode (positive side of the tube) made of _______ because it has a very high _____ _____ and a high ______ ______ (__)

A

tungsten, melting point, atomic number (74)

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3
Q

anode serves as:

A

A target for electron interaction to produce x rays.
As an electrical and thermal conductor

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4
Q

what does the x-ray tube guard against?

A

leakage radiation

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5
Q

photons inside the x-ray tube housing leave through the ______ and are the ______ _____

A

window, primary beam

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6
Q

the x-ray tube housing protects against:

A

electric shock

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7
Q

inside the housing, the x-ray tube is surrounded by ____ (______ ____) - possible cooling fan

A

oil (dissipate housing)

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8
Q

the main purpose of the x-ray tube is to maintain a ______ within the tube to prevent _______ ______

A

vacuum, electrical arcing

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9
Q

__% of the electrons that hit the anode target are turned into heat, and __% are converted to x-ray

A

99%, 1%

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10
Q

what is the advantage of a rotating anode?

A

spreads the heat produced during x-ray production over a larger surface area

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11
Q

anode is made of:

A

copper (shaft)
molybdenum (disc base and core)
tungsten (outside)

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12
Q

the anode is rotates using an:

A

induction motor

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13
Q

what are the two parts of the induction motor?

A

stator & rotor

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14
Q

what is the stator made up of?

A

electromagnets arranged in pairs around the rotor

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15
Q

what is the rotor made up of?

A

iron core (iron bars embedded in the copper shaft) surrounded by coils

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16
Q

what happens when you press the exposure button half way down?

A

Stator windings energized
sequentially & rotor accelerated to designated rpm

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17
Q

what happens when you press the exposure button all the way down?

A

Filament is Heated-Electrons cloud is forming
“BEEP” – kVp is applied, electrons strike the anode, photons are produced

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18
Q

When the angle of the target face is less than __ degrees, the effective focal spot will be smaller than the actual

A

45

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19
Q

The target angles are __ to __ degrees for a general-purpose tube (__ degrees is the most common)

A

7 to 18, 12

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20
Q

The smaller the anode angle, the ______ the effective focal spot will be while maintaining a large actual focal spot area

A

smaller

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21
Q

The _____ the effective focal spot, the sharper the image will be

A

smaller

22
Q

Smaller anode angle = _____ heel effect

A

larger

23
Q

Effective focal spot size is where:

A

the x-rays come out

24
Q

Anode heel effect:

A

intensity is more toward the cathode

25
Q

Cathode side is the ______ side of the tube

A

negative

26
Q

Cathode provides:
and is made up of:

A

The source of electrons needed for x-ray production
The filaments and the focusing cup

27
Q

Dual focus tubes have ___ filaments

A

2

28
Q

Each filament is a coil of wire made of:

A

tungsten with 1-2% of thorium

29
Q

Focusing cup is made of _____ and surrounds the ________ back and sides, leaving the front open and facing the anode target

A

nickel, filaments

30
Q

The focusing cup receives a strong ______ charge from the secondary circuit that forces the _______ together into a cloud as they are boiled off the _______ through electrostatic repulsion

A

negative, electrons, filament

31
Q

Inside the x-ray tube, the induction motor turns the anode at approximately ____ rpm

A

3400

32
Q

Once the space charge reaches a size commensurate with the current used, it becomes difficult for additional electrons to be emitted

A

space-charge effect

33
Q

3 things needed to produce x-rays

A

A large potential difference to give kinetic energy (provided by kVp)
A vehicle in which kinetic energy can ride (provided by mAs)
A place for interaction (the target of the anode)

34
Q

The overall density of our image is the ____

A

black

35
Q

thee difference between the whites and blacks is:

A

contrast

36
Q

A measure of the amount of heat stored in a particular device

A

heat units

37
Q

how to calculate heat units

A

kVp x mA x s x c

38
Q

single phase formula:

A

mA x time x kVp

39
Q

three phase formula:

A

mA x time x kVp x 1.35

40
Q

high frequency formula:

A

mA x time x kVp x 1.40

41
Q

Which if the following reduces leakage radiation to required standards?

A

Protective housing

42
Q

Which component of the x-ray tube us responsible for concentrating the electron cloud?

A

Focusing cup

43
Q

The x-ray tube is part of the:

A

X-ray circuit secondary

44
Q

A technique of 80 kV, 400 mA, 0.8 seconds is to be used on a 3-phase, 12-pulse machine. How many heat units are produced with a single exposure?

A

36,096

45
Q

The intensity of the x-ray beam is less:

which side?

A

On the anode side

46
Q

Causes of tube failure are most often related to which of the following?

A

Thermal characteristics

47
Q

What metal is added to the filament to increase thermionic emission and extend tube life?

A

Thorium

48
Q

A small anode target angle:

results in?

A

Results in an increase in anode heel effect

49
Q

A dual focus tube refers to a tube with:

A

Two filaments

50
Q

The purpose of the line focus principle is to create which of the following?

A

Large actual and small effective focal spot size

51
Q

A technique of 50 kV, 100 mA, 0.1 seconds is to be used on a 3-phase, 6-pulse machine. How many heat units are produced with a single exposure?

A

675