Ch 2 Test Flashcards by Lori Walls

The _____ is the portion of the xray tube that contains the filament

Cathode

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The cathode filament is made of:

Tungsten

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The focusing cup:

Has a negative charge

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In a dual-focus tube, how many filaments are energized at one time during xray production?

One

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The focusing cup is made of:

Nickel

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_______ is the phenomenon that occurs around the filament during thermionic emission and prevents the further escape of electrons from the filament

Space charge effect

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The positive side of the xray tube is the:

Anode

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The maximum speed the rotating anode will typically achieve is _____ rpm

10,000

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What is the base material of the anode disk?

Molybdenum and Graphite

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Name of the fixed physical area on the anode target that is struck by the electron stream?

Focal spot

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What is the name of the device in a rotating anode xray tube that turns the rotor?

Stator

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Effective compensation for the anode heel effect would involve positioning:

The thinnest portion of the part under the anode and the thicker portion of the part under the cathode

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What is an acceptable level of leakage from the tube housing?

1 mGy per hour, measured at a distance of 1 meter

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The production of an xray photon by the electrostatic attraction between the incident electron and the nucleus of the tungsten atom

Bremsstrahlung interaction

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If a projectile electron enters an atom with 100 keV of energy, passes very close to the nucleus, and exits with 30 keV of energy. The xray photon produced is:

70 keV

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Production of an xray photon by a collision between the incident electron and a K-shell electron of the tungsten atom?

Characteristic Interaction

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A projectile electron removes a K-shell electron and an M-shell electron fills the vacancy. the energy of the K-shell characteristic xray photon produced is:

66.7 keV

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______ is the boiling off of electrons from the filament when current is applied

Thermionic Emission

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The actual flow of electrons from cathode to anode is known as:

Tube current

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mA is a measure of _____ that flows from cathode to anode

Tube Current

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Increasing the kVp will….

Increase the penetrants of the beam and increase the speed of the electrons

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The amount the voltage varies during an xray exposure is known as:

Voltage ripple

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What focal spot size is measured directly under the anode target?

Effective focal spot

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Filtration of the xray beam results in:

Increased beam quality

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What is not classified as inherent filtration?

The oil in the transformer

The amount of filtration required to reduce the exposure of the beam to half of its original intensity is

HVL (Half Value Life)

Which of the following types of filtration produce a more inform exposure to the image receptor?

Compensating

To produce x-rays, electrons must be:

-Suddenly decelerated -Liberated from the cathode filament -Suddenly accelerated

The device that nearly surrounds the filament is

Focusing cup

A dual focus tube has 2

Cathode filaments

The rotating target track is primarily made of

Tungsten

The target angle of rotating targets typically ranges from:

5° to 20°

What is the relationship between the tungsten metals atomic number and melting point

Direct

The part of the xray tube that is connected to the target and causes it to turn

Rotor

The advantage to having a focal track is that:

Higher exposure factors can be used to

_______ envelopes are more commonly used in todays xray tubes

Metal

As compared to glass, which is an advantage to having a metal envelope xray tube?

Decrease in off-focus radiation

Inside the xray tube envelop you will find:

Vacuum

The speed the electrons inside the xray tube travel is:

Approximately half the speed of light

Diagnostic xray exposures range from:

30 to 150 keV

With a standard xray tube, ____% of the xray beam produced with 65 kVp is the result of bremsstrahlung interactions

100%

With a standard xray tube ____% of the xray beam produced with 90 kVp is the result of bremsstrahlung interactions?

85%

With a standard xray tube ____% of the xray beam produced with 65 kVp is the result of characteristic interactions?

With a standard xray tube ____% of the xray beam produced with 90 kVp is the result of characteristic interactions?

15%

Xray photon energy is measured in:

keV

The wide range of energies in the xray beam is known as the

Xray emission spectrum

The highest energy xray photons produced with a 100 kVp exposure will be:

100 keV

When making an exposure, what does NOT occur when just the rotor, or prep button is activated?

Voltage is applied across the tube (what DOES occur: Anode begins to rotate, current is applied to the filament, and a space charge is created)

Filament current is approximately

3 to 5 A

During x ray production, the energy of the moving electrons is converted into:

Electromagnetic energy

The quality of the xray beam indicates:

The ability of the photons to penetrate

Due to the anode heel effect, differences in intensities between ends of the xray field can be up to:

45%

Doubling the mA results in:

-Doubling the tube current -Doubling the quantity of xray photons -Doubling the thermionic emission

Decreasing the exposure time results in:

Fewer xray photons

How much is the mAs when 400 mA and 100 ms are used

40 mAs

When electrons strike the anode target; their kinetic energy is converted into ____% heat

99%

The larger the anode angle, the

larger the effective focal spot

Added tube filtration is typically made up of

Aluminum

Xray tubes operating above 70 kVp must have a total filtration of at least ____ of aluminum, or its equivalent

2.5 mm

As kVp increases:

-Beam penetrability increases -Beam wavelength decreases -Beam frequency increases

The amount of heat produced from any given exposure is called a:

Heat Unit (HU)

How many HU are produced when using a 3 phase xray unit: 400 mA, 200 ms, and 70 kVp?

7560 HU 200 milliseconds=0.2 seconds 400 x 0.2 x 70 x 1.35

Setting identical exposure factors, which type of xray unit will produce the greatest heat?

High frequency

In order to produce 12 mAs, how long should the exposure time be when using 600 mA?

0.02 seconds

What practice will extend the life of the xray tube?

Use low mA and longer exposure time and warm up the tube as appropriate

T or F? When an electron from the L-shell of the tungsten atom is ejected from its orbit by a projectile electron, high energy x ray photons are produced

False

T or F? The xray beam produced with 120 kVp will consist primarily of x-rays produced by bremsstrahlung interactions

True

T or F? Electrons can flow from cathode to anode or from anode to cathode during xray exposure?

False

T or F? Electrons can flow from cathode to anode or from anode to cathode during xray exposure?

False

Ch 2 Test Flashcards

(69 cards)