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Radiologic Exposures > Final Review Xray production (interactions in the xray tube) > Flashcards

Final Review Xray production (interactions in the xray tube) Flashcards

1
Q

electrons interacts with the atomic
nucleus, more energy is lost and a stronger x-ray is
produced; account for the majority of the x-ray beam.

A

Bremsstrahlung

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2
Q

electrons interact with an
orbital electron from the atom, the pulling down of
another electron from an outer shell causes an x-ray to be
produced; account for a small majority of the x-ray beam

A

Characteristic Radiation

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3
Q

Be able to label the different interactions based off the diagrams and be able to tell the difference on xray emission spectra (in packet 10 that was handed out)

A
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4
Q

Xrays versus gamma rays

A

-xrays are man made process
-xrays originate from electron cloud of atoms
-gamma rays are a neutral process
-gamma rays originate from atomic nucleus through radioactive decay

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5
Q

Velocity of accelerate electrons

A

Speed of light

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6
Q

Incoming electrons=

A

incident electrons

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7
Q

Increase kinetic energy of incident electrons also increase:

A

-Increases quality and quantity
-increases number of target interactions

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8
Q

Bremmstrahlung is the german term for:

A

“Breaking or slowing radiation”

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9
Q

Bremsstrahlung is responsible for how much percentage of the xrays produced in the xray tube:

A

85%

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10
Q

Molybdenum
-lower atomic number
-ideal for soft tissues of breast

A

Mammography

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11
Q

-high atomic number
-high melting points
-similar binding electrons

A

Tungsten and rhenium

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12
Q

Occur within 2.35-0.5mm of target surface

A

-heat production
-Bremsstrahlung interactions
-Characteristic interactions

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13
Q

Is a very inefficient process

A

xray production

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14
Q

The closer the incident electron passes to the nucleus

A

The higher energy of the photon

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15
Q

Further away to the nucleus

A

The lower energy of the photon

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16
Q

increased wavelength and decreased frequency =

A

decreased energy

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17
Q

decreased wavelength and increased frequency =

A

increased energy

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18
Q

-contains low energy xrays which will be absorbed by the xray tube
-average energy of the beam is 1/3 of the maximum energy
-xrays are an inefficient process
99%heat, 1% converted to xrays

A

Heterogenous Beam

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19
Q

Portion of beam from tube to the patient; radiation before it enters the patient

A

Primary Radiation

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20
Q

Radiation emerging from patients body to expose the film; image forming radiation

A

Remnant Radiation

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21
Q

These 4 prime factors are controlled by the technologist

A

mA- milliampere
S- seconds time
kVp- kilovoltage peak
SID - source to image distance

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22
Q

The range and intensity of xrays emitted changes with different exposure technique settings on the control panel

A

Xray emission spectrum

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23
Q

A Brem photon is the result of

A

The energy difference between the incident electron as it passes (slows) near the nucleus

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24
Q

Brem Radiation involves

A

An incident electron and the nucleus of an atom

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25
Q

The inner shell of an atom

A

K shell

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26
Q

How is brem radiation produced

A

By slowing of an incident electron

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27
Q
A
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27
Q
A
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28
Q

-incident electron interacts with electrostatic force field of nucleus
-Mutual repulsion (slows
electron)
-Strong nuclear force
(Keeps them apart and
deflects incident
electron and repulsion
causes a deceleration
of incident electron)

A

Bremsstrahlung interactions

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29
Q

Brems responsible for wide variety of energies

A

-produces a continuous spectrum of xrays
-heterogenous xray bream

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30
Q

Results of Brems interactions

A

-Deceleration yields xray photons energies
-xray production is continuous during deceleration
-accounts for largest portion of total xray beam
-photon energy dependent on how close electron comes to nucleus and rate of deceleration

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31
Q

Brems energy produced dependent on

A

-how close to the incident photon gets to the nucleus (closer creates increased energy)
- the degree of deceleration of the electron (greater deceleration created increased energy)

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32
Q

Brems process at atomic level :

A

-high speed electron is attracted to the positively charged nucleus
- interaction with nuclear force fields causes electron to slow down and lose energy
-lost kinetic energy converted to X-ray energy

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33
Q

Two interactions part of X-ray production

A

Bremmstruhlung interactions and characteristic interactions

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34
Q

True or false
Electron interacts directly with nucleus

A

False : slim chance an electron will hit or interact with nucleus directly and if that happens all energy will be lost

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34
Q

As incident electron gets closer to nucleus, the following occurs

A

-photon energy increases due to rate of deceleration
- larger deflection of incident electron
-electrons with small amount of residual kinetic energy, become part of electrical current flow

34
Q
A
35
Q
A
36
Q
A
37
Q

Characteristic X-ray production involves

A

Incident electron and inner shell electron

38
Q

Less of a turn=

A

Less energy of a photon

39
Q

The process of adding or removing electrons from an atom is

A

Ionization

40
Q

Responsible for 15% of X-rays produced in the X-ray tube

A

Characteristic

41
Q

Characteristic process at atomic level

A

-high speed incident electron interacts with an inner shell (k or l) shell electron or a target atom
-k or l shell electron is ejected , leaving a vacancy
-electron vacancy filled by another electron from an outer shell (characteristic cascade)
-electron transition responsible for producing a characteristic X-ray photon

42
Q

Binding energy of kshell is

A

69.5

43
Q

Characteristic can be produced at what amount of keV

A

70 or higher

44
Q

What kind of energy spectrum does Brem produce

A

Continuous

45
Q

The process of an outer shell electron filling a vacancy left in an inner shell

A

Characteristic cascade

46
Q

-hole in inner shell and must be filled by electron from any outer shell
- electron energy difference
-secondary photon produced

A

Characteristic cascade

47
Q

What shell is of diagnostic value

A

K shell

48
Q

Brems is produced at what keV

A

anything is less than 70

49
Q

The cascade process is associated with:

A

Characteristic radiation production

50
Q

Changing (blank) will change the maximum energy of the photons in the X-ray emission spectrum

A

KVp

51
Q

A technologist can control the quantity of the X-rays striking the patient by adjusting the

A

mA

52
Q

The maximum kinetic energy of a projectile electron accelerated across an X-ray tube depends on the

A

Kilovoltage

52
Q

Beam quantity is primarily determined by

A

mAs

52
Q

What can be determined from an xray spectrum

A

Maximum photon energy and average photon energy

53
Q

-Brems and characteristic emissions combines
-consists of a “brems hump” and characteristic peak
-selected kvp will determines maximum kev possible for any photon

A

Emission Spectrum

53
Q

Characteristic radiation is produced when:

A

A vacancy in an electron orbit is filled

54
Q

How kilovoltage effects emission spectrum

A

Created potential difference
-determines the speed of the electrons in tube current
-greater speed results in greater quantity and quality of primary beam
-Increasing electron speed will increase xray beam penetribilty
Example:
kvp is increasing, shift to the right, increases average energyaverage and maximum energ increased when kvp is increase

55
Q

How mA affects the emission spectrum

A

Unit to measure tube current or number of electrons flowing per unti time
-mA directly proportional to quantity of xrays produced
-double the mA will double the number of xray photons produced
Example:
mA is increasing so its doubling quantity but mA does not affect the energy of the xray beam

56
Q

xray tube filtration filters out

A

low energy xrays

57
Q

When an incident electron approaches a positive charged nucleus of a tungsten atom

A

The incident electron slows down due to electrostatic attraction

58
Q

Controls the projectile electron energy , intensity, maximum energy and the average energy of the X-ray beam

A

kvp

59
Q

Controls the number of projectile electrons striking the anode and the intensity of the X-ray beam

A

mA

59
Q

Less than 70 KVp is what % is Brems

A

100%

60
Q

Approximately 30-40% of selected KVp

A

Average keV

61
Q

Higher KVp =

A

higher average energy

62
Q

kvp is your…

A

energy (quality)

63
Q

mA is your…

A

Quantity

63
Q

Changes in mA and KVp for regarding emission spectrum

A

Characteristic peak energy levels remain unchanged

64
Q

Change in KVp regarding emission spectrum

A

Changes beam amplitude and average energy

65
Q

Change in generator type

A

Produce a beam with higher average energy

65
Q

Characteristic energy produced dependent on

A

-binding energy of a k shell

-tungsten atom is 69.5 keV

66
Q

aluminum filtration added to xray beam to absorb low energy photons (reduced patient exposure)

A

Beam filtration

67
Q

-added to primary beam to alter its intensity(wedge filter or trough filter)
-used to image nonuniform anatomic areas
-thicker part of filter lines up with thinner part allowing fewer xray photons to reach atomic area

A

compensating filtration

67
Q

Value of the photon energy equals to :

A

The difference of the binding energy of the ionized shell and the transitioning electron

67
Q

Penetrating ability of the xray beam

A

xray beam quality

68
Q

Amount of material required to reduce the X-ray beam intensity to one half its original value

A

Half value layer

69
Q

Factors which affect beam quality

A

-kvp
-filtration

70
Q

Changes the beam quality by changing photon wavelength and an increase causes both the average and maximum energy to increase

A

kvp

71
Q

Factors which affect beam quality and quantity

A

KVp, mA , time, filtration, X-ray circuit waveform

72
Q

Brems interaction in order:

A
  1. High speed incident electron comes close to the nucleus of a tungsten atom
  2. Positive nuclear force field causes the incident electron to change direction
  3. The high speed electron decelerates
  4. The lost kinetic energy is converted to an X-ray photon
73
Q

Characteristic intersection in order :

A

1.High speed projectile electron passes near a K or L shell electron or a tungsten atom

  1. The incident electron ejects the inner shell electron
  2. A vacancy is created in the orbital shell

4.The unstable atom attempts to return to the normal state by filling the vacancy with the outer shell electrons

  1. The movement of outer shell electrons creates a characteristic cascade
  2. The potential energy of each orbital electrons movement is converted to a characteristic photon
74
Q

Energy or motion, type of energy exhibited by incident electrons

A

kinetic

75
Q

what happens to the kvp when the frequency decreases, energy decreases, and wavelength increases

A

kvp decreases

76
Q

What happens to the kvp when frequency increases, energy increases and wavelength decreases

A

kvp increases

76
Q

what happens to the number of photons when exposure time is increased

A

number of xray photons increase

Radiologic Exposures (11 decks)

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