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physics > chapter 7 ( The X ray tube) > Flashcards

chapter 7 ( The X ray tube) Flashcards

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1
Q

Which of the following will not damage the X-Ray tube?

A

Exceeding the ideal field size for an exposure

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2
Q

The main method of heat transfer from the focal spot/target to the rest of the anode is

A

conduction

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3
Q

An exposure rate of 100 mR/hr is the maximum allowed

A

leakage rate

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4
Q

The effective focal spot size is
the actual filament size.

A

smaller than

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5
Q

____________enclosures allow for more support and a constant potential between the tube current and enclosure.

A

Metal

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6
Q

A loud grinding sound from a tube is most likely due to

A

damaged ball bearings

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7
Q

Thermionic emission is the emission of

A

electrons from a heated cathode

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8
Q

In a fixed anode, there are_____
allowable heat loads and a_______
overall target area.

A

low, small

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9
Q

The space charge effect______.

A

occurs in the vicinity of the cathode

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10
Q

Localized pitting on the anode can occur from_______.

A

a single excessive exposure

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11
Q

The external structure of the X-Ray tube includes

A

support structure, protective housing, and tube enclosure

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12
Q

The filament is made of_____.

A

tungsten

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13
Q

Oil is added to the tube housing, creating a layer between the housing and tube enclosure to do what of the following?

A

remove heat from the X-Ray tube enclosure

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14
Q

When saturation is achieved at a fixed filament current, tube current

A

remains the same with increasing kVp

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15
Q

Which of the following could allow for an increase in heat capacity of an anode?

A

a. An increased anode diameter
b. A faster rotation speed
c. A larger focal spot X

d. All of the above

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16
Q

Because of the line focus principle, the effective focal spot size decreases with decreasing

A

target angle

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17
Q

Which of the following is not done by the protective housing?

A

Protection from scatter

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18
Q

The impact of the heel effect on the image is reduced by positioning the cathode

A

over the thickest part of the patient

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19
Q

What is the most common cause of abrupt tube failure?

A

open filament

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20
Q

The heel effect is more pronounced

A

with a small target angle

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21
Q

What does the focusing cup do?

A

help emitted electrons to a small region on the target

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22
Q

The main method of heat transfer from the anode to the tube enclosure is

A

Radiation

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23
Q

Extrafocal or off-focus radiation is produced from

A

rebounding electrons

24
Q

The negative side of the X-Ray tube holds the

A

filament

25
Q

Thermotropic emission allows______
to leave the filament.

A

electrons

26
Q

The target of the rotating anode is usually made of

A

tungsten

27
Q

Thorium is added to the filament to increase

A

thermionic efficiency

28
Q

The______
is the source of X-Rays in the tube

A

focal spot

29
Q

The filaments lay inside the focusing cup which has _____ with respect to the filaments in order to ______ electrons to the beam.

A

negative potential, repel

30
Q

The term “isotropic” means

A

X-Rays are emitted in all directions

31
Q

The typical target angle in general radiography is_____
degrees.

A

15

32
Q

The effective focal spot is determined by the target angle and the_____.

A

filament size

33
Q

The only way to increase saturation tube current is to increase

A

filament current

34
Q

The part that actually turns the anode is the

A

rotor

35
Q

The______
current is always less than the______
current.

A

tube, filament

36
Q

The rotating anode is turned by the induction motor, which uses a

A

changing magnetic field

37
Q

The X-Ray intensity is lower on the anode side of the tube because of the

A

heel effect

38
Q

The X-Ray tube current____.

A

is controlled by the filament current

39
Q

Each tube has its own radiographic rating chart to show

A

maximum exposure techniques

40
Q

The best way to avoid cracking a cold anode is to

A

warm it with several low-technique exposures

41
Q

Dual focus tubes usually have two

A

filaments

42
Q

What are the main functions of the anode?

A

a.
Support the actual target region
b.
Acts as electrical conductor
c.Remove the heat generated

D.
(All of the above )

43
Q

The main method of heat transfer from the tube housing to the room is

A

convection

44
Q

If excessive heat is conducted through the rotor, it could

A

damage ball bearings in the rotor

45
Q

Generally, for the same total mAs, the small focal spot results in exposure times that are ____ a large focal spot

A

greater than

46
Q

The
is/are outside the tube enclosure.

A

stators

47
Q

As an X-Ray tube ages, the inside can become coated with tungsten, which can cause
in the tube.

A

arcing

48
Q

For the same kVp and mAs setting, what waveform would technically generate the most heat units?

A

high frequency

49
Q

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

A

is a poor heat conductor

50
Q

X-Ray tube failure may be due to

A

a. a broken filament
Flag question
b. overheating of the anode
c.
damage to the ball bearings
d. lack of anode rotation

(All of the above)

51
Q

The filament of an X-Ray tube is about_____
in length.

A

1-2 cm

52
Q

The most important property to consider when choosing an anode material is

A

high melting point

53
Q

What is the most probable result of a single exposure made on a tube if the factors slightly exceed those permitted by the radiographic rating chart?

A

The useful life of the tube would be reduced

54
Q

The most widely used support structure for the X-Ray tube is the

A

ceiling support system

55
Q

The effective focal spot size is largest

A

on the cathode side of the tube

physics (4 decks)

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