Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

1126 Final Review > Photon-Electron Interactions > Flashcards

Photon-Electron Interactions Flashcards

1
Q

What are the 3 x-ray interactions with tissue?

A
  • Photoelectric interaction
  • Compton scattering
  • Coherent scattering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a rare xray interaction with tissue?

A

Characteristic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does photoelectric effect work?

A

A x-ray photon interacts with an inner shell electron, transfers all of its energy to the electron which ejects it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the ejected electron called in photoelectric effect?

A

Photoelectron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the photoelectron go on to create?

A

Secondary radiation in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What effect does PE have on images?

A

Play a major role in the subject contrast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do areas on the image appear when no radiation is received on the IR?

A

They appear white or very light gray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is an energy requirement of the incoming photon in PE?

A

Energy of the incoming photon needs to be just above the binging energy of the inner shell electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the energy formula for PE?

A

Ep= Eb + Eke
- Ep is energy of incoming electron
- Eb is the binding energy of orbital electron
- Eke is the energy of the ejected electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is PE related to dose?

A

PE yields most of the patient dose in a given radiograph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is photoelectric effect related to kVp?

A

Photoelectric effect is inversely proportional to the cube of KVp and is reduced as kVp increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are alternate names for Compton interaction?

A

Modified scattering and Incoherent scattering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does Compton scattering work?

A

An incoming Xray interacts with an outer shell electron, partially transfers its energy to the electron, which ejects the electron and creates a new x-ray photon at a different angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the ejected electron called in Compton scattering?

A

Recoil electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the wavelength change between incoming photon and new photon in Compton scattering?

A

Small wavelength to longer wavelength (More energy to less energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the energy formula for Compton scattering?

A

Ep= Es + Eb + Eke
- Ep is energy of incoming electron
- Es is the energy of the scattered xray
- Eb is the binding energy of orbital electron
- Eke is the energy of the ejected electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In a patient how many compton interactions per photon are standard?

A

A single photon can cause a series of compton interaction, each with a new photon of less energy, eventually ending in PE effect and absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What percentage of scatter is compton?

A

97%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What direction does scatter occur in?

A

Occurs in all directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the angle of scatter based on?

A

The original energy of the incoming photon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is scatter called that comes back towards the tube?

A

Back scatter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What direction do scattered xrays that retain most of their energy move in?

A

Move in a forward direction close to that of the original

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What direction do scattered xrays that retain 84% of their energy move in?

A

Move at a right angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What direction do scattered xrays that retain 68% of their energy move in?

A

Move in a backwards direction (back scatter)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What direction do more xrays scatter in and why?

A

Back scatter because most scattered photons have low energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does kVp effect the probability of scatter?

A

kVp increases the energy of the initial photon, and as energy increases so does the probability of scatter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does scatter produce when it hits the IR?

A

Radiographic fog, aka noise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the effect of fog on an image?

A

Obscures details within the image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does coherent scattering work?

A

A low level xray photon interacts with a tightly bound electron, transfers all its energy but only excites the electron to release new photon of same energy at slightly different angle

30
Q

What percent of scatter is caused by coherent scatter?

A

3%

31
Q

What effect does coherent scatter have on the image?

A

Very little effect

32
Q

How does the wavelength change between incoming photon and new photon in Coherent scattering?

A

It doesn’t they stay the same size

33
Q

When does characteristic radiation occur?

A

After an ionizing event in a tissue like compton or photoelectric interaction

34
Q

How does characteristic radiation work?

A

An electron is pulled from an outer shell to fill a vacancy in an inner shell

35
Q

What is the result of characteristic radiation?

A

An extremely low photon or UV light

36
Q

Does characteristic radiation have an effect on the xray image?

A

No it has no effect

37
Q

What types of interactions result in attenuation?

A

Photoelectric effect and compton scattering

38
Q

What type of interaction does photoelectric effect result in?

A

Absorption

39
Q

What type of interaction does compton effect result in?

A

Scattering

40
Q

What is the end result of the photon in photoelectric effect?

A

X-ray photon disappears

41
Q

What is the end result of the photon in compton effect?

A

Xray photon loses energy and changes direction

42
Q

What is another name for photoelectric interaction?

A

Photoelectric absorption

43
Q

What happens to the photon in photoelectric?

A

It is completely absorbed

44
Q

Where does the interaction occur in photoelectric?

A

Inner shell electron

45
Q

What is the general rule of binding energy for photoelectic?

A

Energy must be slightly higher

46
Q

What happens to the electron in photoelectric?

A

The photon gets ejected as a photoelectron

47
Q

What effect does photoelectric have on contrast?

A

Creates the majority of subject contrast in the image

48
Q

What is another name for compton interaction?

A

Modified or incoherent

49
Q

What happens to the photon in compton interaction?

A

Loses a small amount of energy and changes direction, with the angle based on initial energy

50
Q

Where does the interaction occur in compton?

A

In outer shell electrons

51
Q

What is the general rule of binding energy for compton?

A

Equal but generally much higher

52
Q

What happens to the electron in compton?

A

Recoil electron

53
Q

What effect does compton have on contrast?

A

Can be in the remnant beam but reduces contrast

54
Q

What dose is represented by compton?

A

Occupational dose because of the scatter

55
Q

What is another name for coherent scattering?

A

Unmodified or Thompson

56
Q

What happens to the photon in coherent scattering?

A

Initial photon is absorbed by orbital electrons, which causes excitation. A new photon is created and travels at a slightly different angle and possesses the same energy as the initial photon

57
Q

Where does the interaction occur in coherent scattering?

A

Orbital electron

58
Q

What is the general rule of binding energy for coherent scattering?

A

Less energy causing the electron to be excited

59
Q

What happens to the electron as part of coherent scattering?

A

Nothing, it gets excited but there is no ionization

60
Q

What effect does coherent scattering have on image contrast?

A

Little to no effect as only 3% makes it to the IR

61
Q

What is a Rayleigh interaction?

A

A variation of coherent scattering

62
Q

What happens to the photon in Rayleigh interaction?

A

Initial photon is absorbed by entire atom, and a new photon is created at the same energy but at different angle

63
Q

Where does Rayleigh interaction take place?

A

Entire atom is excited

64
Q

Where does characteristic interaction take place?

A

In any shell with an electron vacancy

65
Q

What happens to the electron as part of characteristic interaction?

A

Electron falls into an inner shell vacancy which causes a loss of potential energy and emission

66
Q

What effect does characteristic interaction have on image contrast?

A

Energy created is so low it has no effect on the image and is likely to be light or UV radiation

67
Q

What are some ways to reduce scatter?

A

Reduce kVp, reduce patient size, utilize grids

68
Q

Who/what is compton scatter bad for?

A

The image because it creates noise, the patient because it causes ionization, and anyone in the room bc it leaves the patient

69
Q

What are the other 2 types of interactions that are not used in diagnostic imaging?

A

Pair Production and Photodisintegration

70
Q

How does pair production work?

A

X-ray photons with 1.02 MeV interact with the nuclear field of an atom, which causes the photon to disappear producing a positron and negatron

71
Q

What happens to the Positron in Pair production?

A

It interacts with an electron and annhilates it, producing two photons of .5 MeV energy each

72
Q

How does photodisintigration work?

A

xray photons with energy over 10 Mev get completely absorbed into the nucleus making it explode producing nuclear fragments

1126 Final Review (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions