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Jerry's Image Production > X-Ray Interaction with Matter Ch 9 > Flashcards

X-Ray Interaction with Matter Ch 9 Flashcards

1
Q

How many types of interactions are there with matter?

A
  1. Compton
  2. Photoelectric effect
  3. Coherent
  4. Pair Production
  5. Photodisintegration
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2
Q

What happens to the x-ray beam as it passes through matter?

A
  1. Penetration

2. Attenuation

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3
Q

What is penetration?

A

Photon passes through unchanged to produce a black area on the image receptor

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4
Q

What are the two factors that allow penetration?

A
  1. x-rays are electrically neutral

2. Atoms consist mainly of empty space

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5
Q

The probability of penetration increases with

A
  1. Higher quantity of short wavelength radiation
  2. Less tissue thickness
  3. Lower tissue density (z)
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6
Q

High frequency is ____ wavelength.

A

Short

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7
Q

How do you get a higher quantity of short wavelength radiation?

A
  • Increase kVp
  • Increase Filtration
  • Increase atomic number (z) of the target
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8
Q

What is attenuation?

A
  • Exposure rate is decreased

- X-ray beam can be absorbed or scattered

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9
Q

In attenuation (absorption), the exposure rate is decreased due to what (3) factors?

A
  1. Photon is absorbed in the body producing secondary radiation (characteristic)
  2. Part of the body undergoes a change in direction resulting in scatter radiation (Compton or Coherent)
  3. Inverse Square Law
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10
Q

The probability of attenuation increases with…

A
  • Higher quantity of long wavelength radiation
  • Increased tissue thickness
  • Higher tissue density
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11
Q

The ______ the wavelength the greater the probability of photons interacting with one of the electrons in the shells surrounding the nucleus of an atom in the body.

A

Higher

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12
Q

What is the photoelectric effect?

A
  • The photon entering the body being completely absorbed

- True absorption

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13
Q

What are the results of the photoelectric effect?

A
  • Characteristic radiation (true secondary radiation)
  • Photoelectron (Neg ion)
    • K shell electron that was kicked out
  • Positive Ion
    • Atom that was left behind
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14
Q

If you do not have photoelectric effect, you do not have an…

A

Image

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15
Q

What two things together make up an ion pair?

A

Photoelectron (Neg ion)

Positive Ion

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16
Q

The probability of the photoelectric effect increase with what?

A
  • Atoms with a high atomic number
  • Incident photon having keV = or higher than the binding energy of the inner shell electron
  • Lower energy x-ray photons
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17
Q

What is Compton Interaction?

A

?

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18
Q

What is another word for Compton Interaction?

A

Modified Scatter

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19
Q

What are the results of Compton Interactions?

A

Scattered Photon
Ion Pair
*Recoil Electron- Neg ion
*Positive Ion-

20
Q

The energy of the scattered photon will be dependent on what?

A

It’s angle of deflection

21
Q

If a photon just glances off the e- and is scattered by a small angle, it will retain a ____ _____ of it’s original angle.

A

Large amount

22
Q

The larger the angle, the ____ energy it will retain and the ____ energy is transmitted to the recoil e-.

A

Less/ More

23
Q

The scattered photon will retain up to ____ of it’s original energy.

A

2/3

24
Q

What happens to a scattered photon (produced in the body?)

A
  • It can be transmitted through matter
  • It can be absorbed in a photoelectric interaction with another atom
  • It may result in further Compton interactions
25
Q

Where is a scattered photon produced?

A

In the body

26
Q

The ______ of Compton scatter is a complex function of the energy of the incident x-ray.

A

Probability

27
Q

In general, the probability of the Compton Effect _____ as x-ray energy increases.

A

Decreases

28
Q

As kVp is increased the probability of Compton Interaction…

A

Decreases

29
Q

The probability of Compton scattering does not depend on the ___ ____ of the atom.

A

Atomic number

30
Q

With higher kVp, the Compton photons that do occur have ____ energy.

A

Higher

31
Q

With higher kVp, the Compton photons that do occur have more energy and move in a _____ direction.

A

Forward (toward the IR)

Angle of deflection is small

32
Q

The photons that increase the likelihood of their passing through the body and reaching the image receptor constitutes the scatter radiation, which in radiography impairs the image _______ by an overall fogging effect.

A

Contrast

33
Q

What is the fogging effect?

A

A form of noise that degrades recorded detail

34
Q

Even though fog is on the image, do you still have the detail of the image?

A

Yes, you just can’t see it very well.

35
Q

Compton scattering ______ image contrast.

A

Reduces

36
Q

The photoelectric effect is _____ x-ray absorption.

A

Total

37
Q

What two interactions with matter are important in making an x-ray image?

A

Compton scattering and Photoelectric effect

38
Q

Do x-rays have short or long wavelengths?

A

Very short

39
Q

In Compton scattering, the incident x-ray interacts with an outer shell electron and ____ it from the atom.

A

Ejects

40
Q

What is the ejected electron in Compton scattering called?

A

Compton electron

41
Q

Scattered x-rays provide ___ useful information on the radiograph.

A

No

42
Q

A _____ amount of radiation can be scattered from the patient during fluoroscopy.

A

Large

43
Q

________ radiation during fluoroscopy is the source of most of the occupational radiation exposure that radiographers receive.

A

Scatter

44
Q

What earned Albert Einstein the nobel peace prize in 1921?

A

The discovery of the photoelectric effect

45
Q

The photoelectric effect occurs when an incident x-ray is ______ absorbed during the ionization of an inner shell electron.

A

Totally

Jerry's Image Production (8 decks)

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