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Rad Bio > Chapter 3: Interaction of X-Radiation with Matter > Flashcards

Chapter 3: Interaction of X-Radiation with Matter Flashcards

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1
Q

Highest energy level of photons in the x-ray beam, equal to the highest voltage established across the x-ray tube

A

Peak kilovoltage (kvp)

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2
Q

The product of electron tube current and the amount of time in seconds that the xray tube is activated

A

milliampere- seconds (mAs)

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3
Q

True or False:
No dose is a safe dose

A

True

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4
Q

controls the quality, or penetrating power, of the photons in the x-ray beam and to some degree also affects the quantity, or number of photons, in the beam.

A

Peak kilovoltage

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5
Q

If x-rays enter a material such as biologic tissue, they may:

A
  1. Interact with the atoms of the biologic material in the patient and be absorbed
  2. Interact with the atoms in the biologic material and be scattered, causing some indirect transmission
  3. Pass through without interaction
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6
Q

amount of energy absorbed per unit mass is referred to as the

A

absorbed dose (D).

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7
Q

what is patient dose

A

mas

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8
Q

what decreases patient dose

A

increased kvp and decreased mas

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9
Q

is your current and quantity

A

mas

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10
Q

is your penetration and quality

A

kvp

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11
Q

what are carriers of manmade electromagnetic energy

A

xrays

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12
Q

If an interaction occurs, electromagnetic energy is transferred from the x-rays to the atoms of the patient’s biologic tissue. This process is called

A

absorption

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13
Q

Selects technical exposure factors that control beam quality and quantity

Is actually responsible for the dose the patient receives during an imaging procedur

A

RADIOGRAPHER

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14
Q

what gives you the different shades of gray

A

absorption

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15
Q

what interaction is your absorptoion

A

photoelectric

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16
Q

True or False
Without absorption and the differences in the absorption properties of various body structures, it would not be possible to produce diagnostically useful images in which different anatomic structures could be perceived and distinguished

A

True

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17
Q

Reasons tungsten and tungsten rhenium are used as target materials

A

-high melting points
-high atomic numbers

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18
Q

Target (anode) composition used in general radiograph

A

Tungsten (a metal)Tungsten rhenium (a metal alloy)

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19
Q

where is xray produced

A

at the anode

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20
Q

atomic number of tungsten

A

74

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21
Q

What is produced when a stream of very energetic electrons bombards a positively charged target in a highly evacuated glass tube.

A

A diagnostic x-ray beam is produced

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22
Q

is the x-ray photon beam that emerges from the x-ray tube and is directed toward the image receptor

A

primary radiation

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23
Q

atomic number of rhenium

A

75

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24
Q

As the electrons interact with the atoms of the tube target, what is produced

A

xray photons are produced

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25
Q

are particles associated with electromagnetic radiation that have neither mass nor electric charge and travel at the speed of light

A

Photons

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26
Q

exit from the tube target with a broad range, or spectrum, of energies and leave the x-ray tube through a glass window.

A

xray photons

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27
Q

permits passage of all but the lowest-energy components of the x-ray spectrum. It therefore acts as a filter by removing diagnostically useless, very-low-energy x-rays. In addition to this, a certain thickness of added aluminum is placed within the collimator assembly to intercept the emerging x-rays before they reach the patient.

A

Glass window

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28
Q

what is the average energy

A

1/3 of the kvp

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29
Q

as a whole

A

kvp

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30
Q

individual

A

kev

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31
Q

In diagnostic radiology, the voltage is expressed in thousands of volts, or:

A

kilovolts (kv)

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32
Q

because the voltage across the tube fluctuates, it is usally charcterized by :

A

kilovolt peak value (kvp)

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33
Q

True or False:
Not all photons in a diagnostic xray bean have the same energy

A

True

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34
Q

True or False :
The most energetic photons in the beam can have no more energy than the electrons that bombard the target

A

True

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35
Q

Photons that strike the image receptor are called

A

Transmitted photons

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36
Q

are the photons that have undergone either absorption or scatter and do not strike the image receptor

A

attenuated photons

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37
Q

X-rays sometimes interact with atoms of a patient such that they give up all of their energy and cease to exist. These photons are said to be

A

absorbed

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38
Q

Other photons interact with atoms of the patient, but only surrender part of their energy. They will continue to exist but will emerge from the interaction at a different angle (somewhat like a billiard ball colliding with another billiard ball). These photons are said to be

A

Scattered

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39
Q

Some primary photons will traverse the patient without interacting.
These noninteracting x-ray photons reach the radiographic image receptor (e.g., phosphor plate or digital radiography receptor).

A

Direct Transmission

40
Q

Direct and indirect transmission of x-ray photons
When an x-ray beam passes through a patient, it goes through a process called

A

Attenuation

41
Q

Other primary photons can undergo Compton and/or coherent interactions and as a result may be scattered or deflected with a potential loss of energy. Such photons may still traverse the patient and strike the image receptor

A

Indirect Transmission

42
Q

Decrease in amount of photons reaching IR

A

Attenuation

43
Q

are photons that pass through the patient being radiographed and reach the radiographic image receptor

A

Exit, or image-formation, photons

44
Q

are photons that have interacted with atoms of the patient’s biologic tissue and have been scattered or absorbed such that they do not reach the radiographic image receptor

A

Attenuated Photons

45
Q

are photons that emerge from the x-ray source

A

Primary, exit, and attenuated photons

46
Q

which characteristics are non diagnostic

A

coherent

47
Q

which characteristics are diagnostic

A

photoelectric and compton

48
Q

The two that miss the detector are

A

classified and attenuated

49
Q

Coherent scattering is sometimes also called by the following names:

A
  • Classical scattering
  • Elastic scattering
  • Unmodified scattering
50
Q

When a low-energy (typically less than 10 keV) photon interacts with an atom, it may transfer its energy by causing some or all of the electrons of the atom to momentarily vibrate. This is analogous to the behavior of electrons in the antenna of a receiver intercepting a radio signal. Because they are charged particles, each of the atom’s now vibrating electrons radiates energy in the form of electromagnetic waves. These waves combine with one another, as multiple water waves would similarly merge, to form a resultant scattered wave, or photon. Because the wavelengths of both incident and scattered waves are the same, no net energy has been absorbed by the atom (see Appendix E). However, a small change in direction for the emitted photon is very likely. In general, this change in direction is less than 20 degrees with respect to the initial direction of the original photon. This is the net effect of coherent, or unmodified, scattering. Although coherent scattering is most likely to occur at less than 10 keV (energies that will be eliminated by the inherent filtration), some of this unmodified scattering occurs throughout the diagnostic energy range and can result in small amounts of radiographic fog (Fig. 3.5). This source of fog, however, is not significant in general diagnostic imaging.

A

coherent

51
Q

Interaction of photons with biologic matter is

A

random

52
Q

which interaction is diagnostic and therapeutic

A

Compton

53
Q

A relatively simple process that results in no loss of energy as x-rays scatter

A

coherent scattering

54
Q

It occurs with low-energy photons, typically less than 10 keV

A

coherent scattering

55
Q

Because the wavelengths of both incident and scattered waves are the same, no net energy has been absorbed by the atom (see Appendix E in textbook).
Rayleigh and Thompson scattering play essentially no role in radiography

A

coherent Scattering

56
Q

come in with same energy, leave with same energy

A

coherent

57
Q

-form of scatter
-no loss of energy as xrays scatter
-unmodified

A

coherent

58
Q

Diagnostic radiology energy range: 23 to 150 kVp
This is the most important mode of interaction between x-ray photons and the atoms of the patient’s body for producing useful images

A

Photoelectric Absorption

59
Q

-Inner shell (kshell)
-Absorption
-biological damage , your pt. dose
-creating photoelectron
-one incoming and one leaving (photon coming in, photoelectron leaving)

A

Photoelectric Absorption

60
Q

one incoming and one leaving

A

photoelectric

61
Q

what comes in and what leaves in a photoelectric absorption

A

photon coming in, photoelectron leaving

62
Q

is an interaction between an x-ray photon and an inner-shell electron (usually in the K or L shells

A

photoelectric absorption

63
Q

Discovered by Pierre Victor Auger in 1925
Produces an Auger electron
Is a radiationless effect

A

Auger Effect

64
Q

Probability of Occurrence of Photoelectric Absorption
Depends on

A

Energy (E) of the incident x-ray photons
Atomic number (Z) of the atoms comprising the irradiated object

65
Q

Probability of Occurrence of Photoelectric Absorption
Increases markedly as the

A

E of the incident photon decreases
Z of irradiated atom increases

66
Q

what is brighter and has more absorption, less transmission

A

bone

67
Q

what has less absorption and more transmission

A

soft tissue

68
Q

tightly packed

A

density

69
Q

The less a structure attenuated radiation, the darker or lighter the image will be and vise versa

A

The less a structure attenuates radiation, the darker the image will be and vice versa

70
Q

least dense to most
fat, muscle, bone, organs, metal, air

A

air
fat
muscle
organs
bone
metal

71
Q

what is the binding number of tungsten

A

69.5

72
Q

Compton scattering is also known by the following terms:

A
  • Incoherent scattering
  • Inelastic scattering
  • Modified scattering
73
Q

less attenuation, darker or lighter the image

A

darker the image

74
Q
A
74
Q
A
75
Q
A
76
Q

1 contrast agent

A

air

77
Q

bone higher atomic number ,

A

more absorption

78
Q

increase atomic number, increase absorption, what happens to tranmission

A

decrease

79
Q

As absorption increases, so does the potential for

A

biologic damage

80
Q

true or false
The greater the difference in the amount of photoelectric absorption, the greater the contrast in the radiographic image will be between adjacent structures of differing atomic numbers

A

true

81
Q

Responsible for most of the scattered radiation produced during radiologic procedures

A

Compton

82
Q

which interaction is your occupational dose

A

Compton

83
Q

-occupational dose
-outershell
-modified
-1 incoming, 2 leaving
- decrease contrast

A

compton

84
Q

before it loses energy, it can scatter up to

A

2times

85
Q

every time xray photon scatters it leaves how much original intensity

A

0.1 percent

86
Q

Radiation that has interacted with an atom and traveling in a new direction

A

scatter

87
Q

Process: oIncident photon interacts with electrons in the atom and causes excitationoPhoton exits atom with no loss in energy, no ionizatio

A

coherent scattering

88
Q

Also called classical scattering, unmodified scatter
Occurs at photon E of less than 10 keV

A

coherent scattering

89
Q

Process: oIncident photon interacts with outer shell of the atom oElectron is ejected: termed a “Compton” or “recoil electron”oRemaining energy emitted as a photon (with lower E and longer wavelength) in a new direction; able to exit the patient)

A

compton

90
Q

Responsible for the majority of scatter produced – occupational dose (stand at 90-degree angle)

A

Compton

91
Q

Process: oIncident photon interacts with inner (K or L) shell of the atom oElectron is ejected: termed a “photoelectron”oVacancy filled with an outer shell electronoResults in a characteristic photon being emitted (very low energy; not able to exit the patie

A

Photoelectric Effect

92
Q

Produces the lighter densities on conventional x-ray imagesResults in total absorption of the x-ray photonIncident photon E must be slightly greater than the binding energy of the electronResults in an ionized atomoName of ejected electron is termed a photoelectro

A

photoelectric effect

93
Q

As tissue thickness increases what happens to attenuation, absorption, and transmission

A

Attenuation and absorption would increase as transmission would decrease

94
Q

As the atomic number increases what happens to the attenuation, absorption and transmission

A

Attenuation and absorption increases and transmission decreases

95
Q

As tissue density increases what happens to attenuation, absorption and transmission

A

Attenuation and absorption increases as transmission decreases

Rad Bio (8 decks)

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