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rad105 > Test 2 - Chpt 6 & 11 > Flashcards

Test 2 - Chpt 6 & 11 Flashcards

1
Q

Two interactions that occur in the tungsten target

A

Characteristic
Bremsstrahlung

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2
Q

How does heat production occur

A

When the electrons interact with the outer shell electrons of the tungsten target they cause excitation which causes excess energy to give off as infrared radiation (heat)

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3
Q

Characteristic Interactions

A

Filament electrons enters a target atom and strikes an orbital electron

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4
Q

How does characteristic interactions create photons?

A

If k shell electron is removed from orbit then an electron from the L shell drops to fill the vacancy. It does this by expending some of its PE which is given off as a photon

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5
Q

What shell is most likely to fill an inner shell

A

Adjacent shell

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6
Q

For characteristic photons, energy is dependent on the difference of what?

A

Of the binding energy between the shells involved

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7
Q

Characteristic photon is named for the what?

A

For the shell being filled in each case
K characteristic = L electron filled a K vacancy

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8
Q

How to find the energy of a characteristic photon

A

Binding energy of the farther shell is subtracted from that of the closer shell

(Inner shell - outer shell = photon energy)

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9
Q

What must happen for an orbital electron to be removed

A

Filament electron must have KE equal to or greater than the binding energy of the electron with which it interacts

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10
Q

When the filament electron misses all of the orbital electrons and interacts with the nucleus of the atom

A

Bremsstrahlung interaction

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11
Q

How is a brems photon created?

A

When the filament electron slows down and changes direction because of the attraction to the nucleus it loses KE which is released as a photon

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12
Q

How to find the energy of a brems photon

A

By subtracting the energy that the filament leaves the atom from the energy it had when entering

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13
Q

Why are most of the photons produced brems photons?

A
  • only k shells provide enough energy
  • orbital electrons are in constant motion so easy to miss
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14
Q

Where is added filtration placed?

A

Between the target window and the top of the collimator

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15
Q

Total number of x-ray photons in a beam

A

Beam quantity

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16
Q

What is associated with beam quantity

A

Radiation dose

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17
Q

Intensity of a beam is inversely proportional to the square of the distance

A

Inverse square law

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18
Q

What absorbs low energy photons that do not contribute to the image

A

Filtration

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19
Q

What is beam quality?

A

The penetrating power of the x-ray beam

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20
Q

What creates the dark shades of the image?

A

Photons that reach the image receptor 

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21
Q

What creates the white or clear areas of the image?

A

Areas where no photons reach the image receptor

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22
Q

The thickness of absorbing material necessary to reduce the energy of the beam to 1/2 its original intensity

A

Half value layer, HVL

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23
Q

What is the normal HVL of diagnostic beams

A

3-5 mm Al

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24
Q

The beam that exits the collimator and exposes the patient?

A

Primary beam

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25
Q

Beam that remains after interaction with the patient and is exiting the patient to expose the IR

A

Remnant beam

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26
Q

What is formed within the patient due to interactions with matter/tissue?

A

Secondary photons

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27
Q

For the emission spectrum graph what indicates a change in quantity

A

Y axis (number of x-rays)

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28
Q

For the emission spectrum graph what indicates a change in the quality

A

X axis (x-ray energy)

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29
Q

What five factors change the appearance of the x-ray emission spectrum

A

mA, kVp, tube filtration, generator type, and target material

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30
Q

If you decrease the quantity, what happens to the amplitude of the graph?

A

It decreases

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31
Q

If you increase mA what happens to the amplitude of both the continuous and discrete portions of the spectrum

A

Increases amplitude

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32
Q

If you increase kVp, what happens to the amplitude of both continuous and discrete portions of the spectrum in what way does it shift?

A

Amplitude increases
Shift, right

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33
Q

An increase in tube filtration causes what to happen to the quantity and quality

A

Decrease in quantity
Increase in quality

34
Q

What is directly proportional to radiation quantity reaching the patient and the amount of remnant radiation reaching the IR

A

mAs

35
Q

What is inversely related to exposure time to maintain exposure to IR

A

mA

36
Q

What is directly proportional to radiation quantity

A

Exposure time

37
Q

What is directly related to IR exposure

A

exposure time

38
Q

Image brightness is adjusted during what and for what?

A

computer processing
low and high exposure errors

39
Q

what can exposure errors result in?

A

increased quantum noise visible

40
Q

(T/F) Computer processing can fix overexposed, but not underexposed

A

true

41
Q

What affects the amount of radiation exposure to the IR?

A

kVp

42
Q

Too little radiation reaching the IR increases?

A

noise

43
Q

The advantage of using the 15% rule

A

Changes exposure without changing patient dose
(pregnant women & pathology)

44
Q

How to maintain exposure when adjusting the kVp by 15%?`

A

Change mAs by a factor of 2

45
Q

what is affected when altering the X-ray beams’ penetrating power (2)?

A

absorption and transmission

46
Q

increasing kVp does what to contrast?

A

decreases it

47
Q

Higher kVp reduces the total number of what and increases what?

A

interactions
the X-rays transmitted

48
Q

What does the level of radiographic contrast desired depend on? (3)

A
  • type and comp. of tissue
  • visualized structures
  • doc’s pref
49
Q

Focal spot size affects what of the image?

A

sharpness
(detail/resolution)

50
Q

What affects the amount of radiation reaching the patient?

A

SID

51
Q

What type of relationship does SID and radiation intensity have?

A

inverse relationship

52
Q

What is the inverse square law in WORDS >:{

A

the intensity of the X-ray beam is inversely related to the square of the distance from the source

53
Q

Changing SID requires a change in what to maintain exposure to the IR?

A

mAs

54
Q

Intensity directly relates to the square of what?

A

the distance

55
Q

Direct square law AKA

A

Exposure maintenance formula

56
Q

An increase in SID affects what (decrease or increase) (2)?

A
  • image distortion decreases
  • spatial resolution increases
57
Q

If you can’t decrease OID how can you make up for it?

A

By increasing SID

58
Q

Limiting scatter improves what?

A

quality and contrast

59
Q

Why does using a grid increase patient dose?

A

Need to increase mAs

60
Q

A larger field size increases what and causes what?

A

increases the amount of tissue irradiated
causes more scatter radiation

61
Q

A larger field size does what to contrast? why?

A

Decreases contrast
- the amount of radiation reaching the IR has increased

62
Q

exposure techniques and the amount of radiation output depend on what?

A

the type of generator used

63
Q

generators with more efficient output require what to produce an image?

A

lower exposure technique settings

64
Q

x-ray tubes operated above 70 kVp are required to have a minimum of what?

A

2.5 mm of aluminum filtration

65
Q

increasing tube filtration increases the percentage of what?

A

higher-penetrating X-rays to lower-penetrating X-rays

66
Q

What is beam attenuation?

A

What is left after scatter and absorption

67
Q

part thickness affects what?

A

beam attenuation

68
Q

(T/F) increasing or decreasing part thickness requires a change in mAs to maintain exposure to the IR?

A

True

69
Q

What establishes the environment for X-ray production?

A

The removal of the orbital electron

70
Q

What produces characteristic X-rays once the environment is set?

A

the expending of energy during the cascade

71
Q

Will there be K-shell interactions if a radiographer selects a kVp that’s lower than 70?

A

No, for tungsten it must be equal to or greater than 69.5 keV

72
Q

(T/F) Bremsstrahlung interactions come from the loss of KE from the filament electron

A

true

73
Q

(T/F) The closer the filament electron gets to the nucleus the weaker the attraction

A

False
-The attraction is stronger

74
Q

(T/F) The more energy the filament electron gains the stronger the resultant brems photon

A

False
-The more energy the electron loses

75
Q

The average energy of a brems photon is what of the kVp selected at the control panel?

A

1/3

76
Q

What is the primary contributor to inherent filtration, equating to about 0.5 mm Al Equivalent?

A

target window

77
Q

K-characteristic photons’ energy range

A

57-69 keV

78
Q

What type of relationship do mAs have with the exposure reaching the IR?

A

Direct proportional

79
Q

What type of relationship does mA and time to maintain exposure to the IR?

A

Inverse Proportional

80
Q

Given the anatomic part is adequately penetrated, changing the kVp will affect what (2)?

A

Scattering and contrast

81
Q

The amount of remnant radiation will decrease when you increase what?

A

tissue thickness

rad105 (6 decks)

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