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Donny RAD SCI 2 > Exam 1 Review > Flashcards

Exam 1 Review Flashcards

1
Q

Photoelectric effect strikes:

A

inner shell electron

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2
Q

Clover:
What are the four things that can happen when a photon enters the body:

A

Transmission
Photoelectric absorption
Coherent scatter
Compton Scatter

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3
Q

Clover:
What is transmission?

A

when the photon does not interact with the atoms in the body and just hits the image receptor

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4
Q

Clover:
What are the effects of photoelectric absorption?
Why?
What is not an effect?

A

patient dose (not good for patient, bc of ionization which damages tissues/cells)
image quality (good effect, bc it creates contrast)
does not affect occupational dose bc it is all absorbed in patient

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4
Q

Clover:
What is photoelectric absorption (effect)?

A

photon enters the body
photon hits the inner shell electron
photon gets completely absorbed
electron is now ejected from the atom (ionization)
ejected electron is now a photoelectron
(photon in, electron out)
outer shell electron drops to fill the void (cascade effect, creates characteristics photon (x-ray)

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5
Q

Clover:
How is contrast created?

A

places fill with air (lungs & air bubbles) have low absorption which appear dark
but
parts of the body that contain high tissue (bone & organs) have a high absorption & appear bright (white)

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6
Q

Photoelectric Clover:
Photoelectric absorption depends on four things:
How?
What is an example of this?

A
  • thickness levels (more thickness (dense) = more matter = more absorption)
    (chest with lungs= less dense, abdomen= more dense)
  • atomic number (low atomic number = low photoelectric absorption)
    (why we use barium & iodine for high atomic number (more absorption)
  • less energy (kVp or beam energy)
    (lower energy (kVp means less penetration)
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7
Q

Photoelectric Clover:
If kVp increases, energy ___ & intensity ____

A

increases
increases

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8
Q

Photoelectric Clover:
What are the key take aways for photoelectric effect?

A

photoelectric effect (absorption) is more likely at lower kVp levels
increases patient dose
no effect on occupational dose
positive effect on image quality (due to increased contrast)

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9
Q

Photoelectric Clover:

A
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10
Q

In photoelectric effect x-ray photon ceases:

A

to exist

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11
Q

In Photoelectric the electron absorbs all:

A

the x-ray’s photon’s energy

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12
Q

In photoelectric effect the inner shell electron ____ ups &:

A

speeds
leaves the atom

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13
Q

In photoelectric effect the energy in excess of binding energy is given to:

A

the inner-shell electron

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14
Q

In photoelectric effect is _____ likely to occur when the _____ of the incident x-ray is slightly ______ than the binding energy of the orbital electron

A

more
energy
higher

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15
Q

In photoelectric effect increased kVp leads to ________

A

decreased photoelectric absorption

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16
Q

In Compton scatter the x-ray photon ceases:

A

to exist

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17
Q

In Compton scatter _________ interacts (strikes) with an:

A

incident x-rays
outer shell electron

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18
Q

In photoelectric effect increased atomic number leads to increased

A

photoelectric absorption (because more things to interact with)

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19
Q

Compton Clover:
What is the most common type of scatter?
What does it negatively effect?

A

-compton (least desired photon interaction)
-patient dose, occupational dose, image quality

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20
Q

Compton Clover:
How does Compton scatter happen?

A
  • x-ray photon strikes an outer shell electron & is partially absorbed
  • electron is now knocked out of orbit (ionization)
  • ejected electron is now reffered to as a compton electron
  • the rest of the energy (post ejecting the electron) is now a scattered photon (going in complete opposite direction)
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21
Q

Compton Clover:
What are the effects of Compton scatter?
How does it affect these things?

A

-increased patient dose (ionization, creates free electron that causes damage to surrounding tissue & the scatter photon can be absorbed in the patients’ tissues)
-occupational dose (creates scatter that can hit anything/anyone, no. 1 source of occupational dose)
-image quality (creates scatter thus decreasing image contrast quality)

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22
Q

Compton Clover:
What is the number one source of occupational radiation dose?

A

Compton scatter

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23
Q

Compton Clover:
How do we get a high contrast image?
What does compton scatter do in this situation?

A

-combination of photoelectric effect & transmission (creates good contrast in image anatomy (whites & blacks)
- compton scatter creates meaningless “noise” (decreased image contrast)

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24
Compton Clover: When it comes to part thickness, what happens to compton scatter? How can we manipulate this rule?
more matter = more scatter less matter = less scatter -by collimation to only include areas needed thus decreasing the matter & scatter
25
Compton Clover: what does higher kVp do to scatter and contrast?
higher kVp = more (proportionally scatter) = decrease contrast (bc scatter is up)
26
Compton Clover: Ideally do we want scatter?
scatter is bad, we don't want it to make it to the IR (for image contrast quality)
27
Compton Clover: How can we reduce the amount of compton scatter?
- decrease part thickness (compressing patient down (if possible) - smallest field size -collimated as much as possible - lower kvp setting
28
Compton Clover: Key take aways from Compton scatter:
- compton scatter occurs at all energy levels (main interaction at high energies) - increases patient dose (bc of ionization) -increases occupational dose (bc of scatter) -decrease image quality (bc it decreases image contrast quality)
29
In Compton scatter the electron absorbs:
all the x-rays energy
30
In Compton scatter remaining energy is ______ as a new x-ray and leaves the _____ in a random direction
reemitted atom
31
In Compton scatter outer shell electron speeds up and leaves:
the atom (recoil electron)
32
In Compton scatter some of the energy excess of binding energy is given to an:
outer shell electron
33
Compton scatter is proportionally more likely:
at high kVp levels
34
Both the photoelectric effect and compton scatter lead to
ionization (the removal of an electron from orbit and net positive charge to the atom)
35
Coherent Clover: How does Coherent scatter happen?
-xray photon enters an atom in the body -temporarily absorbed by the atom - x-ray photon exits the atom as a scatter photon (after interacting with the atom) (photon in, photon out)
36
Coherent Clover: What are other names for coherent scattering?
-Thomson scatter -classical scatter -unmodified scatter -elastic scatter -Rayleigh scatter
37
Coherent Clover: What are the effects of coherent scatter? What does it not effect?
- affects image quality (creates scatter, decreasing image contrast quality)  -no occupational dose (bc its a forward scatter (toward image receptor) - none on patient dose (no energy absorbed & no ionization = no biological harm)
38
Coherent Clover: Does Coherent scatter harm the patient? Why?
no no ionization or energy absorbed
39
Coherent Clover: What does scatter always do to the image quality?
decreases the contrast quality of the image, increasing the noise (adds random dark spots)
40
Coherent Clover: what effect does photon energy have on coherent scatter and contrast?
low energy (extremely low)= greater coherent scatter= this decreases contrast (image quality, very minor) (coherent scatter is likely to occur at very very low energies)
41
Coherent Clover: What is the least likely photon interactions?
Coherent scatter
42
Coherent Clover: What type of scatter is worse than coherent?
compton scatter
43
Coherent Clover: Key take aways from Coherent scatter:
-coherent scatter only occurs at very low energies -very unlikely to happen - no effect on patient/ occupational dose just a SMALL negative effect on image quality (contrast, all scatter does this)
44
In Coherent when an incident x-ray interacts with an orbital electron it is:
Thompson
45
In coherent scatter when an incident x-ray interacts with an entire atom is it called:
Rayleigh
46
In coherent scatter when the energy of the incident photon is ______ than the ________ no ________ occurs
less binding energy ionization
47
In coherent scatter the orbital electron reaches a temporary:
state of excitation
48
In coherent scatter the incident x-ray continues:
in a new direction
49
In coherent scatter no _____ occurs
energy transfer
50
Clover attenuation: What is attenuation?
a reduction in the x-ray beam intensity bc of absorption & scatter
51
Clover attenuation: What are the 3 things that can happen when a photon passes through a patient? which two of these apply to attenuation?
- absorption, transmission, scattered - only absorption & scatter
52
Clover attenuation: What does intensity refer to? What is the name of the beam before it passes through the matter (patient)? What do we call the beam after it passes through the patient (after attenuation)?
- the number of x-ray photons (kVp) -primary beam (before all the absorption/scatter (attenuation) -remnant beam (or exit beam) (think flashlight shinning through paper)
53
Clover attenuation: What are some of the attenuation interactions?
-photoelectric absorption (completely absorbed by inner shell electron, photon in, electron out (photon being absorbed) -coherent scattering (photon is temporarily absorbed, photon in, scattered photon out) -Compton scattering (partially absorbed outer shell electron, remaining energy is scattered (this qualifies as both attenuations which is scatter + absorption)
54
Clover attenuation: What does attenuation depend on?
-part thickness (more thickness = more attenuation (more things to interact with) -tissue density (muscle & fat attenuate more than air (abdomen vs chest) (same thickness, but different attenuation chest is less dense) -atomic number (bone atomic no. is significantly higher creating more attenuation (hip replacement attenuates the most due to the high atomic no.) -beam energy (low kVp = less penetration) (high kVp = more penetration, which is less attenuation proportionally)
55
Clover attenuation: Key take aways from attenuation:
-attenuation is a reduction in beam intensity (via scatter/absorption) - photoelectric, compton, & coherent are all attenuation - Attenuation depends on part thickness, beam energy, atomic #, & tissue density
56
Attenuation is?
the reduction in number or intensity of xrays reaching the image receptor
57
Attenuation is absorption & scattering as a result of:
photoelectric effect compton scatter coherent scatter
58
Attenuation can be affected by?
Tissues thickness (every 4 cm = 50% xray beam attenuation) tissue atomic number (more z#= more attenuation) tissue density (most important ex: air vs muscle vs fat) muscle most dense/ air least dense
59
For each 4cm of tissue requires doubling of mAs & kVp by:
15% kVp 100% mAs
60
Clover mAs:
61
Clover mAs:
62
Clover mAs:
63
Clover mAs:
64
Clover mAs:
65
Clover mAs:
66
Clover mAs:
67
Clover mAs:
68
Clover mAs:
69
Clover mAs:
70
Clover mAs:
71
mAs is a measurement of what? it is considered: what is it not?
electron flow in a conductor an electrical term a unit of radiation output
72
mA is limited by what?
Focal spot size
73
Radiologic time is measured in? written as?
seconds .25 secs or 250 ms or 1/4 second (all the same)
74
To calculate the mAs we:
multiply mA x Time
75
mAs is the primary controller of:
intensity/quanity in the remnant beam
76
Doubling in mAs leads to:
doubling of intensity or quantity
77
How do we reduce motion?
setting the shortest time while maintaining same mAs output
78
300 mA and .2 sec
60 mAs (300 x .2)
79
200 mA and .2 sec
40 mAs
80
100 mA and .5 sec
50 mAs
81
Spatial resolution clover: What is spatial resolution? What can this also be referred to as?
-the structural sharpness recorded in the x-ray (important to have excellent spatial resolution, can also be referred to as the ability to distinguish between two structures very very close together) - high detail, high sharpness, low blur
82
Spatial resolution clover: spatial resolution is not the same as:
contrast, brightness, distortion, or receptor exposure
83
Spatial resolution clover: How is spatial resolution measured?
line-pairs per millimeter LP/mm
84
Spatial resolution clover: Spatial resolution take aways: What can affect spatial resolution?
-patient size & patient movement (patient factors) -SID, OID, Focal spot size (FFS) (beam geometry) - image receptor factors (detector element size, pitch, & fill factor) -pixel size, matrix size (digital image factors) -pixel size, pixel pitch, & matrix size (digital display factors)
85
Image quality (magnification) clover: What is magnification distortion? Will there always be magnification?
-describes the size difference between the actual anatomy and how it looks on an x-ray (heart appearing larger than normal) -yes there will always be some kind of magnification bc of the xray beam
86
Image quality (magnification) clover: Why does magnification happen? What affects magnification? As SID decreases: As OID decreases: as SOD increases:
-it is inevitable outcome from the divergent beam -SID, OID, SOD -magnification increases -magnification decreases - magification decreases -
87
Image quality (magnification) clover: How do we can calculate the magnification factor? What does an 1.5 MF mean?
-image size/object size or SID/SOD -the image is 1.5 times larger than the actual object
88
Image quality (magnification) clover:
89
Image quality (magnification) clover:
90
Image quality (magnification) clover:
91
Kilovoltage is the measurement of
electrical force
92
kVp means?
kilo voltage peak (the highest value in electrical generator)
93
the small increase of 15% will?
double the exposure to the image receptor
94
What does kVp control?
the quality of the x-ray beam
95
What does a higher kVp do?
increase the x-ray's ability to penetrate through a particular tissue
96
Maintaining density: 150 mAs to 300 mAs 72 kVp to ___ ?
61.2 (reduced 15%, cuts exposure in half)' mAs doubled kVp needs to come down 15% to maintain
97
when the kvp increases 15% patient exposure increases by:
1/3
98
What is preferred, optimal kVp or minimal kvp?
optimal kVp
99
kVp math: increase kVp 15% of 70 kvp: decrease kVp 15% of 100 kVp:
80.5 (70 x 1.15) 85 (100 x .85)
100
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105
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106
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107
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108
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109
OID stands for?
object image distance (patient distance from IR)
110
optimal brightness and contrast settings are determined by the
radiologists
111
SID stands for?
source to image receptor (x-ray tube to
112
SOD stands for?
Source to object (x-ray tube to patient)
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Donny RAD SCI 2 (4 decks)

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