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Rad physics > exam 5,7,8 > Flashcards

exam 5,7,8 Flashcards

(60 cards)

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1
Q

What do the rectifiers in the secondary circuit do?

A

convert AC to DC

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2
Q

Which waveform has the lowest percentage voltage ripple?

A

High-frequency

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3
Q

According to the Line-Focus Principle, an anode with a small angle provides:

A

improved recorded detail
improved heat capacity

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4
Q

The most common cause of x-ray tube failure is:

A

Vaporized tungsten on glass envelope

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5
Q

Double-focus x-ray tubes have two:

A

Focal spots, Filaments

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6
Q

The function of the cathode is to produce

A

thermionic cloud

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7
Q

Filament materials are chosen primarily for their

A

high melting points

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8
Q

What affects the production of a thermionic cloud?

A

filament diameter,
filament length,
filament temperature

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9
Q

What causes a filament to break

A

vaporization

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10
Q

Driving the thermionic cloud from the cathode to the anode requires

A

a high voltage

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11
Q

The cathode focusing cup has a ____ charge

A

negative

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12
Q

Tungsten is the material of choice for the source of x-ray photons primarily because of its

A

high atomic number

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13
Q

Pitting of the anode commonly occurs

A

with extended use

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14
Q

Cracking of the anode typically occurs

A

when a cold anode is hit with a high kVp exposure

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15
Q

The actual focal spot is controlled by the

A

length of the filament

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16
Q

As the actual focal spot size increases, the effective focal spot size

A

increases

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17
Q

As the angle of the anode increases and the incident electron beam size remains the same, the effective focal spot size

A

increases

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18
Q

The use of the line-focus principle causes a problem known as the ____ effect.

A

anode heel

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19
Q

What type of radiation is composed of photons not produced at the actual focal spot?

A

off-focus
extra-focal

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20
Q

As an x-ray tube ages, the inside can become coated with tungsten, which can cause _____ in the tube.

A

arcing

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21
Q

Thermionic emission at the filament creates a __________.

A

space charge

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22
Q

When electrons bombard the target, ____% of their kinetic energy is converted to heat.

A

99

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23
Q

The ___________ is the source of radiation in the x-ray tube.

A

focal spot

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24
Q

Tube failure can occur from _______________.

A

long exposure times

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25
A dual focus tube has two _______.
filaments
26
The single function of an AEC is to eliminate the need to set
time
27
When using an AEC, the radiographer loses control of
mAs
28
The most common AEC configuration includes
three chambers a center chamber at the center of the image receptor the left and right chambers slightly higher and lateral.
29
When an AEC is used for an AP lumbar spine, which ionization chambers are utilized?
the center cell
30
When an AEC is used for a PA chest, which ionization chambers are utilized?
the left and right outer cells
31
If the primary beam is collimated from an activated chamber, the result is a
dark radiograph
32
During x-ray production, almost all of the kinetic energy of the incident electrons is converted t
heat
33
The transfer of the incident electrons’ kinetic energy to the outer-shell electrons, causing vibration of the outer-shell electron, results in the emission of
infrared radiation
34
The energy of a bremsstrahlung photon is
the difference between the entering and exiting kinetic energies of the incoming electron
35
Characteristic interactions may occur only when the incident electron interacts with
an inner-shell electron
36
During a characteristic interaction, the kinetic energy of the incident electron must be ____ of the electron it knocks from its orbit.
greater than that
37
At the end of the characteristic cascade, the ____ shell is missing an electron.
outermost
38
The K shell can hold a maximum of ____ electrons.
2
39
When comparing the x-ray emission spectrum between beams produced at 70 kVp and 110 kVp,
the 110 kVp beam would demonstrate more brems and a higher characteristic spike.
40
Projectile electrons travel from ______________.
cathode to anode
41
Most of the heat generated at the target is due to ___________.
outer-shell excitation
42
The useful characteristic x-rays from tungsten targets are ___-shell x-rays.
K
43
Bremsstrahlung x-rays are produced by ______________ at the target.
slowing electrons
44
The quantity of bremsstrahlung radiation increases proportionately with increased _____.
mAs
45
What percentage of target interaction results in the production of x-ray photons?
1%
46
What is required for x-ray production?
Source of electrons, rapid acceleration, rapid decleration
47
What is the source of electrons in the x-ray tube?
cathode filament
48
Whaty is the technical factor that accelerates electrons in the x-ray tube?
kVp | controls energy
49
What happens during thermionic emission?
Free electrons are created
50
What kind of current is required to induce thermionic emission?
high
51
What does Bremsstrahlung radiation interact with?
electric field of the nucleus
52
What variables affect the energy of a bremsstrahlung photon?
energy of the incident electron, proximty of the electron to the nucleus
53
What controls the energy of bresstrahlung photons?
tube potential | kVp
54
The types of target interactions that occur during x-ray photon production in the diagnostic range are dependent on what factor?
instant electrons kinetic energy
55
What is the energy of the brems photon?
the difference between the entering and exiting kinetic energies
56
A bremstralung interaction only occur when the instant electron interacts with?
the forcefield around the nucleus
57
Charectiristic interactions may occurs only when the instant electrons only interact with?
inner shell
58
During a characteristic interaction the energy of the incident electron must be what
greater
59
During a characteristic interaction the dropping of a higher state electron into a lower state results in?
photon
60
The energy of the characterstic photon is?
the difference of the binding energy of the outer and inner shells.

Rad physics (5 decks)

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