x ray beam

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88 Terms

1
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<p>(Milliamperage)(time) --&gt; mAs</p><ul><li><p>mA is a user selectable control (sometimes it can be constant)<br></p><ul><li><p>if constant, <span><strong>[what's the problem?]</strong></span></p></li></ul></li></ul><p></p>

(Milliamperage)(time) --> mAs

  • mA is a user selectable control (sometimes it can be constant)

    • if constant, [what's the problem?]

patient motion is a risk that it will blur the image

2
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<p>(Milliamperage)(time) --&gt; mAs</p><ul><li><p>Milliamperage is <span><strong>[...]</strong></span></p></li><li><p>mAs is <span><strong>[...]</strong></span></p></li></ul><p></p>

(Milliamperage)(time) --> mAs

  • Milliamperage is [...]

  • mAs is [...]

  • quantity of photons

  • the total number of photons/radiations during a specific time of exposure 

3
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<p>15% change in Kilovoltage</p><ul><li><p>Quality of photonic energy is <span><strong>[...]</strong></span></p></li><li><p>Quantity of photons is also <span><strong>[...]</strong></span></p></li></ul><p></p>

15% change in Kilovoltage

  • Quality of photonic energy is [...]

  • Quantity of photons is also [...]

  • increased (peak is further down)

  • increased (increased area under the curve) 

4
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<p>15% Rule</p><ul><li><p>In order to maintain image density, an increase of kVp by 15% should be accompanied by a <span><strong>[...]</strong></span>% <span><strong>[increase or decrease]</strong></span> of mAs</p></li></ul><p></p>

15% Rule

  • In order to maintain image density, an increase of kVp by 15% should be accompanied by a [...]% [increase or decrease] of mAs

50% decrease

Inc. in 15% of kVp = dec. in 50% of mAs

5
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<p>4 basic factors affecting quantity of x-ray beam photons</p><ol><li><p><span><strong>[...]</strong></span></p></li><li><p><span><strong>[...]</strong></span></p></li><li><p><span><strong>[...]</strong></span></p></li><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ol><p></p>

4 basic factors affecting quantity of x-ray beam photons

  1. [...]

  2. [...]

  3. [...]

  4. [...] 

  1. (Milliamperage)(time) --> mAs

  2. Kilovoltage (kVp)

  3. Distance

  4. Filtration 

6
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Absorbed Dose (D)

  • Conversion

    • One gray = [...] Joule (J) of energy deposited per kilogram

    • One rad = [...] ergs of energy deposited per gram

    • 1 Gy = [...] Rads

    • 1 rad = [...] mGy 

  • 1

  • 100

  • 100

  • 10

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Absorbed Dose (D)

  • D = [...]

  • Units:

    • SI system – Gray (Gy)

    • Non-SI – Rads 

E/M

8
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Absorbed Dose (D)

  • D = E/M

  • Units:

    • SI system – [...]

    • Non-SI – [...] 

  • Gray (Gy)

  • Rads

9
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<p><span>As a polyenergetic beam goes through objects, how does it impact the HVL?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

As a polyenergetic beam goes through objects, how does it impact the HVL? 

  • [...] 

  • Since the beam is getting more energetic, HVL increases after each obstacle because the thickness needed to decrease beam intensity has to go up when beam intensity is increasing 

10
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Basic interactions with matter

  • Insignificant

    • [...]

    • [...]

    • [...]

  • Significant

    • Photoelectric absorption

    • Compton Scatter 

  • Coherent scatter (5%)

  • Pair Production

  • Photodisintegration

11
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Basic interactions with matter

  • Insignificant

    • Coherent scatter (5%)

    • Pair Production

    • Photodisintegration

  • Significant

    • [...]

    • [...] 

  • Photoelectric absorption

  • Compton Scatter 

12
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Basics of Attenuation

  • Factors increasing attenuation

    • [...]

    • [...]

    • [...] 

  • Density

  • Atomic Number (Z)

  • Electrons per gram of tissue 


  • Density = denser objects will decrease intensity and therefore increase attenuation

  • Atomic Number (Z) = higher atomic numbers present more obstacles (more electrons, protons, etc.) and therefore increase attenuation

  • Electrons per gram of tissue 

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<p>Compton Scatter Angle of deflection</p><ul><li><p>Greater the angle, the <span><strong>[more or less]</strong></span> energy is lost&nbsp;</p></li></ul><p></p>

Compton Scatter Angle of deflection

  • Greater the angle, the [more or less] energy is lost 

more

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<p><span>Does an x-ray beam have more or less energy after it goes through a wall?</span></p><ul><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

Does an x-ray beam have more or less energy after it goes through a wall?

  • [...]

  • An x-ray beam that makes it through a wall has more energy because only the strong beams make it through the wall

15
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<p><span>Does changing the kilovoltage affect the quality?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span></p></li><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

Does changing the kilovoltage affect the quality? 

  • [...]

  • [...]

  • yes, overall effect on film blackening is approximately equal to the fourth power

  • peak is moved to the right a little 

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<p><span>Does doubling the Milliamperage change energy distribution?</span></p><ul><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

Does doubling the Milliamperage change energy distribution?

  • [...]

  • does NOT change energy distribution (peak is at the same spot) 

17
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Dose Equivalent (H)

  • H = [...] x [...]

  • absorbed dose x quality factor





H = D x QF 

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Dose Equivalent (H)

  • Quality factor – derived from LET values

    • QF of x-rays, Gamma, electrons, beta particles is [...]

      • So, 1 rad = [...] rem in diagnostic radiology

    • QF may be as high as 20 for alpha particles/heavy nuclei 

  • 1.0

  • 1

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Dose Equivalent (H)

  • Units for Dose Equivalent (H)

    • SI system – [...]

    • Non- SI – [...]

    • Conversion rates

      • 1 Sv = 100 rem

      • 1 rem = 10 mSv

  • Sievert (Sv)

  • Rem (rad. Equiv. man)

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Dose Equivalent (H)

  • Units for Dose Equivalent (H)

    • SI system – Sievert (Sv)

    • Non- SI – Rem (rad. Equiv. man)

    • Conversion rates

      • 1 Sv = [...] rem

      • 1 rem = [...] mSv

  • 100

  • 10

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<p>Doubling Filter Thickness</p><ul><li><p><span><strong>[increase or decrease]</strong></span> quality</p></li><li><p><span><strong>[increase or decrease]</strong></span> quantity</p></li></ul><p></p>

Doubling Filter Thickness

  • [increase or decrease] quality

  • [increase or decrease] quantity

  • Increases

  • Decreases

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<p>Doubling Filter Thickness</p><ul><li><p><span><strong>[how does it affect quality?]</strong></span></p></li><li><p><span><strong>[how does it affect quantity?]</strong></span></p></li></ul><p></p>

Doubling Filter Thickness

  • [how does it affect quality?]

  • [how does it affect quantity?]

  • Rightward shift of the peak which means there is a higher quality of energy produced (bc lower energy x-rays are filtered out)

  • Area under the curve decreases because the quantity of the energy decrease (bc some of the photons are obviously being eliminated)


23
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<p>Effect of Milliamperage Doubling</p><ul><li><p><span><strong>[what happens to quality?]</strong></span></p></li><li><p><span><strong>[what happens to quantity?]</strong></span></p></li></ul><p></p>

Effect of Milliamperage Doubling

  • [what happens to quality?]

  • [what happens to quantity?]

  • Quality of photonic energy is NOT affected (peak is at the same spot)

  • Quantity of photons double (area under the curve is doubled)

24
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<p>Effective Atomic Numbers of Various Materials Important to Diagnostic Radiology</p><ul><li><p>Contrast Agents = <span><strong>[...]</strong></span>, <span><strong>[...]</strong></span>, <span><strong>[...]</strong></span><br></p><ul><li><p>Helps to have clearer images</p></li></ul></li></ul><p></p>

Effective Atomic Numbers of Various Materials Important to Diagnostic Radiology

  • Contrast Agents = [...], [...], [...]

    • Helps to have clearer images

Air, Iodine, Barium

25
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<p>Effective Atomic Numbers of Various Materials Important to Diagnostic Radiology</p><ul><li><p>Human tissue (fat, muscle, lung, bone)<br></p><ul><li><p><span><strong>[what has the highest effective atomic number]</strong></span></p></li><li><p>Overall <span>low</span> effective atomic numbers</p><ul><li><p><span>Indicates a low BE that is so low that none of the characteristic radiation will exit the body but will rather be absorbed</span>&nbsp;</p></li></ul></li></ul></li></ul><p></p>

Effective Atomic Numbers of Various Materials Important to Diagnostic Radiology

  • Human tissue (fat, muscle, lung, bone)

    • [what has the highest effective atomic number]

    • Overall low effective atomic numbers

      • Indicates a low BE that is so low that none of the characteristic radiation will exit the body but will rather be absorbed 

  • Bone has the highest effective atomic number

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<p>Effective Atomic Numbers of Various Materials Important to Diagnostic Radiology</p><ul><li><p>Human tissue (fat, muscle, lung, bone)<br></p><ul><li><p><span>Bone has the highest effective atomic number</span></p></li><li><p>Overall <span><strong>[high or low]</strong></span> effective atomic numbers</p><ul><li><p><span><strong>[what does this indicate about absorption?]</strong></span>&nbsp;</p></li></ul></li></ul></li></ul><p></p>

Effective Atomic Numbers of Various Materials Important to Diagnostic Radiology

  • Human tissue (fat, muscle, lung, bone)

    • Bone has the highest effective atomic number

    • Overall [high or low] effective atomic numbers

      • [what does this indicate about absorption?] 

  • low

  • Indicates a low BE that is so low that none of the characteristic radiation will exit the body but will rather be absorbed 

27
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Factors decreasing attenuation

  • [...]

  • Kilovoltage




increasing kVp will just increase punching power so it will just break through matter like hulk 

28
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<p><span>How are beam intensity and mA related?</span></p><ul><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

How are beam intensity and mA related?

  • [...] 

  • Beam intensity and mAs are directly proportional

    • Doubling mAs will double the number of emitted x-rays 

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HVL [increases or decreases] with increasing filtration

increases

High-Value Layer: thickness of an aluminum absorber that is required to reduce beam intensity by 50% 

30
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HVL increases with [increased or decreased] filtration

increasing

High-Value Layer: thickness of an aluminum absorber that is required to reduce beam intensity by 50% 

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<p>If you want to use the barium as the contrast agent, what should the x-ray kVp be set as?&nbsp;</p><ul><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

If you want to use the barium as the contrast agent, what should the x-ray kVp be set as? 

  • [...] 

  • Barium = 37.4 K-shell binding energy. So, set the x-ray machine to about 112 so that the peak will be at about 37.4 (1/3 of the total) and therefore allowing a photoelectric reaction 

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<p>Intensity (exposure) = product of number of photons &amp; their average energy</p><ul><li><p>Intensity = (<span><strong>[...]</strong></span>)(<span><strong>[...]</strong></span>)</p></li><li><p>Unit of measurement = Roentgen (R)<br></p><ul><li><p>1 R = <span>amount of radiation to liberate 2.58e-4 Coulombs per kg of air</span></p></li></ul></li></ul><p></p>

Intensity (exposure) = product of number of photons & their average energy

  • Intensity = ([...])([...])

  • Unit of measurement = Roentgen (R)

    • 1 R = amount of radiation to liberate 2.58e-4 Coulombs per kg of air

(quantity)(quality)

33
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<p>Intensity (exposure) = product of number of photons &amp; their average energy</p><ul><li><p>Intensity = (<span>quantity</span>)(<span>quality</span>)</p></li><li><p>Unit of measurement = Roentgen (R)<br></p><ul><li><p>1 R = <span><strong>[...]</strong></span></p></li></ul></li></ul><p></p>

Intensity (exposure) = product of number of photons & their average energy

  • Intensity = (quantity)(quality)

  • Unit of measurement = Roentgen (R)

    • 1 R = [...]

  • amount of radiation to liberate 2.58e-4 Coulombs per kg of air

34
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<p><span>Inverse Square Law</span></p><ul><li><p>Doubling distance from x-ray source <span><strong>[increases or decreases]</strong></span> intensity by a factor of <span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

Inverse Square Law

  • Doubling distance from x-ray source [increases or decreases] intensity by a factor of [...] 

  • decreases

  • 4

Radiation intensity varies inversely with the distance squared from the source


SAME number of photons, just diluted with distance

35
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<p><span>Is it safer to increase the distance between you and the x-ray beam or is lead better?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

Is it safer to increase the distance between you and the x-ray beam or is lead better? 

  • [...]

distance

36
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Linear Energy Transfer (LET)

  • High LET has [high or low] penetration but [high or low] absorption

  • Low LET has [high or low] penetration but [high or low] absorption 

  • Low, High

  • High, low

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Linear Energy Transfer (LET)

  • [directly or inversely] related to particle KE 

Inversely

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Linear Energy Transfer (LET)

  • [high or low] LET = photons electrons, gamma, & x-rays

  • [high or low] LET = neutrons, protons, and alpha particles 

  • low

  • high

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Lower HVL means the beam has [...]

too many low-beam photons

High-Value Layer: thickness of an aluminum absorber that is required to reduce beam intensity by 50% 


HVL increases with filtration, so a low HVL doesn't have much filtration which means a lot of low energy photon gets through 

40
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<p>Monoenergetic Attenuation</p><ul><li><p><span><strong>[how does a monoenergetic beam respond to more HVL layers?]</strong></span></p></li></ul><p></p>

Monoenergetic Attenuation

  • [how does a monoenergetic beam respond to more HVL layers?]

With more HVL layers, a monoenergetic beam decreases in quantity (number of photons)

41
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<p><span><strong>With more HVL layers, a monoenergetic beam <u>decreases in quantity</u> (number of photons)</strong></span></p>

With more HVL layers, a monoenergetic beam decreases in quantity (number of photons)

nearly the same 

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<p>PE vs Compton Scatter Probabilities</p><ul><li><p>Relative probabilities<br></p><ul><li><p>Almost everything we see in imaging is due to <span><strong>[PE or Compton]</strong></span> because they’re what is present in high x-ray energies</p></li><li><p>Safety factor: x-ray machine with high kVp potential usually require lead placed into the wall as a precaution, because <span>you don’t know where the electrons will scatter</span></p></li></ul></li></ul><p></p>

PE vs Compton Scatter Probabilities

  • Relative probabilities

    • Almost everything we see in imaging is due to [PE or Compton] because they’re what is present in high x-ray energies

    • Safety factor: x-ray machine with high kVp potential usually require lead placed into the wall as a precaution, because you don’t know where the electrons will scatter

Compton scatters

43
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<p>PE vs Compton Scatter Probabilities</p><ul><li><p>Relative probabilities<br></p><ul><li><p>Almost everything we see in imaging is due to <span>Compton scatters</span> because they’re what is present in high x-ray energies</p></li><li><p>Safety factor: x-ray machine with high kVp potential usually require lead placed into the wall as a precaution, because <span><strong>[...]</strong></span></p></li></ul></li></ul><p></p>

PE vs Compton Scatter Probabilities

  • Relative probabilities

    • Almost everything we see in imaging is due to Compton scatters because they’re what is present in high x-ray energies

    • Safety factor: x-ray machine with high kVp potential usually require lead placed into the wall as a precaution, because [...]

  • you don’t know where the electrons will scatter

44
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<p>PE vs Compton Scatter Probabilities</p><ul><li><p>With water<br></p><ul><li><p>Photoelectric reactions increase with <span><strong>[increase or decreased]</strong></span> kVp</p></li><li><p>Compton Scatter reactions increase with <span><strong>[increase or decreased]</strong></span> kVp&nbsp;</p></li><li><p>At <span>26</span> kVp, 50% of interactions are photoelectric and Compton scatter&nbsp;</p></li></ul></li></ul><p></p>

PE vs Compton Scatter Probabilities

  • With water

    • Photoelectric reactions increase with [increase or decreased] kVp

    • Compton Scatter reactions increase with [increase or decreased] kVp 

    • At 26 kVp, 50% of interactions are photoelectric and Compton scatter 

  • decreased

  • increased

Meaning at low kVp, our bodies are significantly absorbing radiation

45
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<p>PE vs Compton Scatter Probabilities</p><ul><li><p>With water<br></p><ul><li><p>Photoelectric reactions increase with <span>decreased</span> kVp</p></li><li><p>Compton Scatter reactions increase with <span>increased</span> kVp&nbsp;</p></li><li><p>At <span><strong>[...]</strong></span> kVp, 50% of interactions are photoelectric and Compton scatter&nbsp;</p></li></ul></li></ul><p></p>

PE vs Compton Scatter Probabilities

  • With water

    • Photoelectric reactions increase with decreased kVp

    • Compton Scatter reactions increase with increased kVp 

    • At [...] kVp, 50% of interactions are photoelectric and Compton scatter 

26

Meaning at low kVp, our bodies are significantly absorbing radiation



46
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<p>PE vs Compton Scatter Probabilities</p><ul><li><p><strong>With bone</strong><br></p><ul><li><p>Photoelectric reactions increase with <span><strong>[increased or decreased]</strong></span> kVp</p></li><li><p>Compton Scatter reactions increase with <span><strong>[increased or decreased]</strong></span> kVp</p></li><li><p>At <span>45</span> kVp, 50% of interactions are photelectric and Compton scatter</p></li></ul></li></ul><p></p>

PE vs Compton Scatter Probabilities

  • With bone

    • Photoelectric reactions increase with [increased or decreased] kVp

    • Compton Scatter reactions increase with [increased or decreased] kVp

    • At 45 kVp, 50% of interactions are photelectric and Compton scatter

  • decreased

  • increased

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<p>PE vs Compton Scatter Probabilities</p><ul><li><p><strong>With bone</strong><br></p><ul><li><p>Photoelectric reactions increase with <span>decreased</span> kVp</p></li><li><p>Compton Scatter reactions increase with <span>increased</span> kVp</p></li><li><p>At <span><strong>[...]</strong></span> kVp, 50% of interactions are photelectric and Compton scatter</p></li></ul></li></ul><p></p>

PE vs Compton Scatter Probabilities

  • With bone

    • Photoelectric reactions increase with decreased kVp

    • Compton Scatter reactions increase with increased kVp

    • At [...] kVp, 50% of interactions are photelectric and Compton scatter

45

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<p>Photoelectric Reaction</p><ul><li><p>(<span><strong>[...]</strong></span>) – (<span><strong>[...]</strong></span>) = KE of the electron that escapes</p></li></ul><p></p>

Photoelectric Reaction

  • ([...]) – ([...]) = KE of the electron that escapes

(Energy of the incident photon) – (electron BE)

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<p>Photoelectric Reaction</p><ul><li><p>3 basic products:<br></p><ol><li><p><span><strong>[...]</strong></span></p></li><li><p><span><strong>[...]</strong></span></p></li><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ol></li></ul><p></p>

Photoelectric Reaction

  • 3 basic products:

    1. [...]

    2. [...]

    3. [...] 

  • Photoelectron

  • Characteristic radiation

  • Positive ion 

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<p>Photoelectric Reaction</p><ul><li><p>Photon is absorbed<br></p><ul><li><p><span><strong>[describe the process.]</strong></span></p></li></ul></li><li><p>Atom resolves energy imbalance by <span>dropping an outer orbital electron</span>&nbsp;</p></li></ul><p></p>

Photoelectric Reaction

  • Photon is absorbed

    • [describe the process.]

  • Atom resolves energy imbalance by dropping an outer orbital electron 

  • incident photon interacts with an inner orbital, K or L, electron with an energy higher than the electron’s binding energy, which causes the electron to be ejected & the photon to be absorbed

<ul><li><p><span><strong>incident photon interacts with an inner orbital, K or L, electron with an energy higher than the electron’s binding energy, which causes the electron to be ejected &amp; the photon to be absorbed</strong></span></p></li></ul><p></p>
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<p>Photoelectric Reaction</p><ul><li><p>Photon is absorbed<br></p><ul><li><p><span>incident photon interacts with an inner orbital, K or L, electron with an energy higher than the electron’s binding energy, which causes the electron to be ejected &amp; the photon to be absorbed</span></p></li></ul></li><li><p>Atom resolves energy imbalance by <span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

Photoelectric Reaction

  • Photon is absorbed

    • incident photon interacts with an inner orbital, K or L, electron with an energy higher than the electron’s binding energy, which causes the electron to be ejected & the photon to be absorbed

  • Atom resolves energy imbalance by [...] 

  • dropping an outer orbital electron 

<ul><li><p><span><strong>dropping an outer orbital electron</strong></span>&nbsp;</p></li></ul><p></p>
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<p>Photoelectric Reaction</p><ul><li><p>Similar to spike of characteristic spike except for some key differences:<br></p><ul><li><p>Atomic number is much <span><strong>[higher or lower]</strong></span> than Tungsten</p></li><li><p><span>Photon is coming in and knocking an electron out of its orbital instead of another electron coming in</span></p></li><li><p>Much <span><strong>[higher or lower]</strong></span> energy&nbsp;</p></li></ul></li></ul><p></p>

Photoelectric Reaction

  • Similar to spike of characteristic spike except for some key differences:

    • Atomic number is much [higher or lower] than Tungsten

    • Photon is coming in and knocking an electron out of its orbital instead of another electron coming in

    • Much [higher or lower] energy 

  • lower

  • lower

<ul><li><p>lower</p></li><li><p>lower</p></li></ul><p></p>
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<p>Photoelectric Reaction</p><ul><li><p>Similar to spike of characteristic spike except for some key differences:<br></p><ul><li><p>Atomic number is much <span>lower</span> than Tungsten</p></li><li><p><span><strong>[what knocks the electron out of its orbital in a photoelectric reaction]</strong></span></p></li><li><p>Much <span>lower</span> energy&nbsp;</p></li></ul></li></ul><p></p>

Photoelectric Reaction

  • Similar to spike of characteristic spike except for some key differences:

    • Atomic number is much lower than Tungsten

    • [what knocks the electron out of its orbital in a photoelectric reaction]

    • Much lower energy 

  • Photon is coming in and knocking an electron out of its orbital instead of another electron coming in

<ul><li><p><span><strong>Photon is coming in and knocking an electron out of its orbital instead of another electron coming in</strong></span></p></li></ul><p></p>
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<p>Photoelectric Reaction</p><ul><li><p>Yields <span><strong>[strong or weak]</strong></span> characteristic radiation in biologic system&nbsp;<br></p><ul><li><p><span>Much lower energy so it can’t travel for long before it is completely absorbed (if it’s a human, it won’t leave the body)</span>&nbsp;</p></li></ul></li></ul><p></p>

Photoelectric Reaction

  • Yields [strong or weak] characteristic radiation in biologic system 

    • Much lower energy so it can’t travel for long before it is completely absorbed (if it’s a human, it won’t leave the body) 

weak

<p>weak</p>
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<p>Photoelectric Reaction</p><ul><li><p>Yields <span>weak</span> characteristic radiation in biologic system&nbsp;<br></p><ul><li><p><span><strong>[what is the significance of this?]</strong></span>&nbsp;</p></li></ul></li></ul><p></p>

Photoelectric Reaction

  • Yields weak characteristic radiation in biologic system 

    • [what is the significance of this?] 

  • Much lower energy so it can’t travel for long before it is completely absorbed (if it’s a human, it won’t leave the body) 

<ul><li><p><span><strong>Much lower energy so it can’t travel for long before it is completely absorbed (if it’s a human, it won’t leave the body)</strong></span>&nbsp;</p></li></ul><p></p>
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<p>Polyenergetic Attenuation</p><ul><li><p>When going through more obstacles, a polyenergetic beam <span><strong>[...]</strong></span></p></li></ul><p></p>

Polyenergetic Attenuation

  • When going through more obstacles, a polyenergetic beam [...]

decreases in quantity and increases in quality

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<p><span>Polyenergetic beam becomes <strong>[...]</strong> after 3 to 4 HVL’s&nbsp;</span></p>

Polyenergetic beam becomes [...] after 3 to 4 HVL’s 

functionally monoenergetic

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<p>Radiation intensity varies inversely with the <strong>distance squared from the source</strong></p><ul><li><p>Due to <span><strong>[...]</strong></span></p></li></ul><p></p>

Radiation intensity varies inversely with the distance squared from the source

  • Due to [...]

the X-Ray beam divergence

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  • shifting the peak indicates a change in [...] 

  • changing the area under the curve indicates a change in [...] 

  • quality 

  • quantity

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<p>the tighter electrons are bound in orbit, photoelectric reaction is more likely</p><ul><li><p>Photoelectric reaction likelihood = <span><strong>[...]</strong></span></p></li></ul><p></p>

the tighter electrons are bound in orbit, photoelectric reaction is more likely

  • Photoelectric reaction likelihood = [...]

  • (atomic number)3



Higher atomic number = higher BE = tighter the electrons are bound


so higher the atomic number, the more likely a PE reaction would occur

<ul><li><p><span><strong>(atomic number)<sup>3</sup></strong></span></p></li></ul><p><br></p><p><em><br></em></p><p><em>Higher atomic number = higher BE = tighter the electrons are bound<br></em></p><p><em><br></em></p><p><em>so higher the atomic number, </em><strong><em>the more likely a PE reaction would occur</em></strong></p>
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<p><span>the tighter electrons are bound in orbit, photoelectric reaction is <strong>[more or less]</strong> likely&nbsp;</span></p>

the tighter electrons are bound in orbit, photoelectric reaction is [more or less] likely 

more

P.E. = Z3

<p><span><strong>more</strong></span></p><p><span>P.E. = Z</span><sup>3</sup></p>
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<p>To get through a thicker layer, you can either increase kVp or increase mAs. What is safer?</p><ul><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

To get through a thicker layer, you can either increase kVp or increase mAs. What is safer?

  • [...] 

  • kVp’s is actually saver

    • more radiation is deposited by low kVp 

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Two basic factors affecting quality of x-ray beam photons (shifts the curve)

  1. [...]

  2. [...]

  1. Kilovoltage (kVp)

  2. Filtration


But the only one that can be changed is the kVp because filtration is required by law

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Vocabulary

  • [...]: photons pass through unaffected

    • Matter is NOT ionized

  • [...]: transfer energy to absorbing medium

    • Matter IS ionized

  • [...]: photons change energy and possibly lose energy  

    • Matter MAY OR MAY NOT be ionized 

  • Penetrate

  • Absorbed

  • Scattered

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Vocabulary

  • Penetrate: photons pass through unaffected

    • [Is matter ionized?]

  • Absorbed: transfer energy to absorbing medium

    • [Is matter ionized?]

  • Scattered: photons change energy and possibly lose energy  

    • [Is matter ionized?] 

  • Matter is NOT ionized

  • Matter IS ionized

  • Matter MAY OR MAY NOT be ionized 

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<p><span>What does the term "beam hardening" mean?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

What does the term "beam hardening" mean? 

  • [...] 

increaseing effective beam energy through preferential loss of lower (softer) energy photons 

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<p><span>What has the lowest HVL &amp; what does that indicate?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

What has the lowest HVL & what does that indicate? 

  • [...]

  • Lead is the most efficient at cutting down x-ray beam so it is the best shield

    • A much thinner lead filter can do the same work as thicker cm. of muscle or bone




High-Value Layer: thickness of an aluminum absorber that is required to reduce beam intensity by 50% 

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<p><span>What is the ONLY interaction between x-ray and matter that does not cause ionization?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

What is the ONLY interaction between x-ray and matter that does not cause ionization? 

  • [...]

  • Coherent Scatter



Low energy photons are simply absorbed & causes a vibration of the electron cloud before it goes back to the same energy 



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<p><span>What is the relationship between beam intensity and kVp?&nbsp;</span></p><ul><li><p><span><strong>[...]</strong></span></p></li></ul><p></p>

What is the relationship between beam intensity and kVp? 

  • [...]

  • Beam intensity is directly proportional to kVp2

    • Defines the quantitative effect

    • It is exponential!!!

      • Doubling the kVp increases beam intensity fourfold & vice versa

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[...]

  • Measures the amount of radiation energy (E) absorbed per unit mass (M) of the absorbing medium

  • Medium must be specified 

Absorbed Dose (D)

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[...]: reduction of energy as energy passes through matter 

Attenuation

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<p><span><strong>[...]</strong></span></p><ul><li><p>Typically <strong>low energy interactions</strong> in which radiation undergoes <span>a change in direction but no changes in wavelength (aka energy)</span>&nbsp;</p></li></ul><p></p>

[...]

  • Typically low energy interactions in which radiation undergoes a change in direction but no changes in wavelength (aka energy) 

Coherent Scattering

Low energy photons are simply absorbed & causes a vibration of the electron cloud before it goes back to the same energy

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<p><span>Coherent Scattering</span></p><ul><li><p>Typically <strong>low energy interactions</strong> in which radiation undergoes <span><strong>[...]</strong></span>&nbsp;</p></li></ul><p></p>

Coherent Scattering

  • Typically low energy interactions in which radiation undergoes [...] 

  • a change in direction but no changes in wavelength (aka energy) 



Low energy photons are simply absorbed & causes a vibration of the electron cloud before it goes back to the same energy 

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<p><span><strong>[...]</strong></span></p><ul><li><p>Description<br></p><ul><li><p>Photon interacts with outer orbital electron, imparting some energy to the outer orbital electron and ejects it from the orbit</p><ul><li><p>Ejected electron is called the <span>Compton electron</span>, which has an energy equal to the excess imparted by the photon</p></li></ul></li><li><p><span>Photon, as a result, is scattered with less energy due to the collision (less energy means larger wavelength in the end)</span></p></li></ul></li></ul><p></p>

[...]

  • Description

    • Photon interacts with outer orbital electron, imparting some energy to the outer orbital electron and ejects it from the orbit

      • Ejected electron is called the Compton electron, which has an energy equal to the excess imparted by the photon

    • Photon, as a result, is scattered with less energy due to the collision (less energy means larger wavelength in the end)

Compton Scatter

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<p><span>Compton Scatter</span></p><ul><li><p>Description<br></p><ul><li><p>Photon interacts with outer orbital electron, imparting some energy to the outer orbital electron and ejects it from the orbit</p><ul><li><p>Ejected electron is called the <span><strong>[...]</strong></span>, which has an energy equal to the excess imparted by the photon</p></li></ul></li><li><p><span>Photon, as a result, is scattered with less energy due to the collision (less energy means larger wavelength in the end)</span></p></li></ul></li></ul><p></p>

Compton Scatter

  • Description

    • Photon interacts with outer orbital electron, imparting some energy to the outer orbital electron and ejects it from the orbit

      • Ejected electron is called the [...], which has an energy equal to the excess imparted by the photon

    • Photon, as a result, is scattered with less energy due to the collision (less energy means larger wavelength in the end)

Compton electron

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<p><span>Compton Scatter</span></p><ul><li><p>Description<br></p><ul><li><p>Photon interacts with outer orbital electron, imparting some energy to the outer orbital electron and ejects it from the orbit</p><ul><li><p>Ejected electron is called the <span>Compton electron</span>, which has an energy equal to the excess imparted by the photon</p></li></ul></li><li><p><span><strong>[what's the energy of the resultant photon?]</strong></span></p></li></ul></li></ul><p></p>

Compton Scatter

  • Description

    • Photon interacts with outer orbital electron, imparting some energy to the outer orbital electron and ejects it from the orbit

      • Ejected electron is called the Compton electron, which has an energy equal to the excess imparted by the photon

    • [what's the energy of the resultant photon?]

  • Photon, as a result, is scattered with less energy due to the collision (less energy means larger wavelength in the end)

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[...]

  • Attempts to quantify biologic damage from deposition in tissues

Dose Equivalent (H)

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<p><span><strong>[...]</strong></span>: source related term used to express intensity of an X-Ray</p><ul><li><p>Source is basically the anode</p></li><li><p>Units<br></p><ul><li><p>SI System --&gt; <span>Coulombs per kg (C/kg)</span></p></li><li><p>Non-SI System --&gt; <span>Roentgens (R)</span>&nbsp;</p></li></ul></li></ul><p></p>

[...]: source related term used to express intensity of an X-Ray

  • Source is basically the anode

  • Units

    • SI System --> Coulombs per kg (C/kg)

    • Non-SI System --> Roentgens (R) 

Exposure

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<p><span>Exposure</span>: source related term used to express intensity of an X-Ray</p><ul><li><p>Source is basically the anode</p></li><li><p>Units<br></p><ul><li><p>SI System --&gt; <span><strong>[...]</strong></span></p></li><li><p>Non-SI System --&gt; <span><strong>[...]</strong></span>&nbsp;</p></li></ul></li></ul><p></p>

Exposure: source related term used to express intensity of an X-Ray

  • Source is basically the anode

  • Units

    • SI System --> [...]

    • Non-SI System --> [...] 

  • Coulombs per kg (C/kg)

  • Roentgens (R) 

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[...]: thickness of an aluminum absorber that is required to reduce beam intensity by 50%

Half-Value Layer

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<p><span><strong>[...]</strong> = potential difference between cathode filament and anode target&nbsp;</span></p>

[...] = potential difference between cathode filament and anode target 

Kilovoltage (kVp)

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<p><span><strong>[...]</strong> has the highest effective anatomic number, indicating it is best option for a shield&nbsp;</span></p>

[...] has the highest effective anatomic number, indicating it is best option for a shield 

Lead

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[...]

  • Energy absorbed by the medium per unit length of travel (keV per micrometer)

  • Proportional to (particle charge) 2

Linear Energy Transfer (LET)

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Linear Energy Transfer (LET)

  • Energy absorbed by the medium per unit length of travel (keV per micrometer)

  • Proportional to [...]

  • (particle charge) 2

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[...] and [...]

  • Ultra high energy interactions with matter that blows the nucleus apart 

  • They do NOT occur in the diagnostic x-ray energy ranges

  • Might be helpful in radiation therapy 

Pair Production and Photodisintegration

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Pair Production and Photodisintegration

  • Ultra high energy interactions with matter that blows the nucleus apart 

  • They do NOT occur in the diagnostic x-ray energy ranges

  • Might be helpful in [...] 

radiation therapy

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<p><span><strong>[...]</strong></span></p><ul><li><p>Interaction with matter where x-ray is absorbed and not scattered&nbsp;</p></li></ul><p></p>

[...]

  • Interaction with matter where x-ray is absorbed and not scattered 

Photoelectric Reaction

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<p><span><strong>[...]</strong></span>&nbsp;</p><ul><li><p>radiation that makes it through matter (could be the patient) to the other side&nbsp;</p></li></ul><p></p>

[...] 

  • radiation that makes it through matter (could be the patient) to the other side 

Remnant Radiation