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Rad Quality I > The Subject (Patient) and Radiobiology > Flashcards

The Subject (Patient) and Radiobiology Flashcards

1
Q

What are the different shades of gray on a film the result of?

A

differing amounts of photons making it through the patient (differential absorption)

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2
Q

What happens to the photons that don’t make it?

A

they are attenuated

attenuation = any interaction that removes a photon from the primary beam

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3
Q

What is the term for any interaction that removes a photon from the primary beam?

A

attenuation

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4
Q

What is transmission the opposite of?

A

attenuation

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5
Q

What is the term for an x-ray that passes through the patient?

A

transmission

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6
Q

What impact will an increase kVp have on transmission?

A

it will increase transmission

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7
Q

What are the two types of Attenuation of our focus?

A

Compton Scatter

Photoelectric Effect

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8
Q

What is the most common interaction of attenuation?

A

Compton Scatter

~90%

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9
Q

Where is the photon hitting the atom in Compton Scatter? And what happens?

A

hits OUTER shell electron –> electron is ejected–> photon deflected–> photon loses energy

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10
Q

Does Compton Scatter or Photoelectric Effect ionize the atom? Is this good or bad?

A

BOTH ionizes atom

it is BAD

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11
Q

Which type of attenuation deflects (scatters) the photon?

A

Compton Scatter

scatter = BAD; we want to reduce is as much as possible

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12
Q

What does the angle of deflection occurring during Compton Scatter depend on?

A

the energy lost to electron

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13
Q

What does a larger angle tell us about the energy lost during Compton Scatter?

A

larger angle = more energy lost

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14
Q

At what angle does the electron deflect between for Compton Scatter? Greater than what angle is it considered “backscatter”?

A

0 to 180 degrees

greater than 90 called backscatter

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15
Q

Of the attenuated interactions, what percentage does the Photoelectric Effect make up?

A

~10%

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16
Q

Where does the photon hit during the Photoelectric Effect? What then happens?

A

hits INNER shell electron –> electron ejected–> photon disappears–> outer shell electrons fill “hole” –> gives off radiation

17
Q

What type of Attenuated interaction is the photon absorbed?

A

Photoelectric Effect

18
Q

During the Photoelectric Effect, what must the energy be of the photon in order to eject the electron?

A

greater than the binding energy of the inner shell electron

19
Q

What other interaction does the Photoelectric Effect should similar to?

A

Characteristic X-rays w/in the tube–> the only difference is the in the tube it is electron hitting electron

20
Q

Out of the Photoelectric Effect and the Compton Scatter, which one deflects and which one absorbs?

A

Photoelectric = absorbs

Compton Scatter = deflects

21
Q

When we increase the kVp, how is the percent of Photoelectric and Compton interactions change?

A

increase kVp will:

  • decrease percent of Photoelectric interaction
  • increase percent of Compton scatter
22
Q

Which type of Attenuation is it when the photon does not reach the film? What does this give our film?

A

Photoelectric Effect

CONTRAST

23
Q

Which type of Attenuation is it when the photon reaches the film? How does this impact contrast?

A

Compton Scatter

creates fog–> decreases film contrast and adds shades of gray

24
Q

What effect will more Transmission have on the absorption, shade, and density?

A

less absorption

darker shade

higher film density

25
Q

What effect does less Transmission have on absorption, shade, and density?

A

more absorption

lighter shade

lower film density

26
Q

What four things does Scatter production depend on?

A
  1. density
  2. kVp
  3. atomic number of material
  4. amount of tissue imaged
27
Q

Out of the four things that produce Scatter, which two can be controlled?

  1. density
  2. kVp
  3. atomic number of material
  4. amount of tissue imaged
A

kVp and amount of tissue imaged (collimation)

28
Q

What are the three ways that we can reduce the amount of tissue imaged to reduce scatter?

A
  1. collimate in (increase collimation)
  2. Recumbent– have the patient lay down –> flattens out tissue due to gravity
  3. use a grid
29
Q

What is a grid for x-ray taking? What does it do?

A

a thin plate in front of Bucky/image receptor

it is innumerable amount of thin strops of lead that STOP scatter from reaching the film

Rad Quality I (5 decks)

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