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2403 Physics > Chapter 8 Exam > Flashcards

Chapter 8 Exam Flashcards

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1
Q

Which of the following describes the process of radiographic image formation?
a. Beam attenuation
b. Differential absorption
c. Dynamic imaging
d. Ionization

A

b. Differential absorption

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2
Q

X-rays can eject electrons from atoms. This is known as:
a. Beam attenuation
b. Differential absorption
c. Dynamic imaging
d. Ionization

A

d. Ionization

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3
Q

The x-ray interaction with anatomic tissue that is responsible for scattering is:
a. Ionization
b. Photoelectric
c. Compton
d. Absorption

A

c. Compton

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4
Q

Which of the following will increase beam attenuation?
a. Higher kilovoltage
b. Decreasing tissue density
c. Thicker anatomic part
d. Lower atomic number

A

c. Thicker anatomic part

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5
Q

Factors that decrease x-ray absorption include:
a. Increased tissue density
b. Increased x-ray beam quality
c. Increased tissue thickness
d. Increased atomic number

A

b. Increased x-ray beam quality

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6
Q

The range of exposure intensities an image receptor can accurately detect defines:
a. Pixel bit depth
b. Dynamic range
c. Ionization
d. Attenuation

A

b. Dynamic range

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7
Q

Digital image quality is improved with:
a. Larger pixel sizes
b. Smaller pixel bit depths
c. Increased tissue density
d. Larger matrix size

A

d. Larger matrix size

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8
Q
  1. Increasing the pixel bit depth will:
    a. Decrease scattering
    b. Increase contrast resolution
    c. Decrease image quality
    d. Increase pixel size
A

b. Increase contrast resolution

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9
Q

What type of imaging system uses an intensifying screen to convert x-rays to visible light?
a. Film-screen
b. Image intensifier
c. Digital
d. Flat-panel detector

A

a. Film-screen

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10
Q

Film-screen imaging has a wider dynamic range than digital imaging
a. True
b. False

A

b. False

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11
Q

Dynamic imaging of internal structures can be visualized with a/an:
a. Image intensifier
b. Flat panel detector
c. Film-screen
d. a and b

A

d. a and b

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12
Q

The process of differential absorption to form an image is the same for digital, film-screen, and fluoroscopy
a. True
b. False

A

a. True

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13
Q

What device receives the x-rays?

A

image receptor

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14
Q

What are the “steps” to producing an x-ray image? (after x-ray production)

A
  • Image receptor can accurately detect a wide dynamic range of exposure intensities
  • Anatomic areas of widely different attenuation such as soft tissues and bony structures can be more easily visualized because of the wider dynamic range
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15
Q
  • Number of bits that determines the amount of precision in digitizing the analog signal and therefore the number of shades of gray that can be displayed in the image
  • Determines the shades of gray displayed on the monitor
  • Calculated as 2^n
A

bit depth

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16
Q

A combination of rows and columns, of small, usually square “picture elements” called pixels (how the digital image is displayed)

A

matrix

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17
Q

The range of exposure intensities an image receptor can accurately detect

A

wide dynamic range

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18
Q

For a given FOV, increasing the matrix size will _______ the pixel size and _______ image quality

A

decrease, increase

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19
Q

For a given FOV, decreasing the matrix size will _______ the pixel size and _______ image quality

A

increases, decrease

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20
Q

The amount of pixels in the image, size of the matrix

A

Pixel density

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21
Q

the difference between the x-ray photons that are absorbed photoelectrically and those that penetrate the body

A

Differential absorption

22
Q

the reduction in the energy or number of photons in the primary x-ray beam.
- two processes occur: absorption and scattering

A

Attenuation

23
Q

the removal of electrons from the inner shell and filling it with the outer shells. Is responsible for total absorption of the incoming x-ray photon.
- occur throughout the diagnostic range 20 kVp-120kVp

A

Photoelectric absorption (effect)

24
Q

doesn’t provide useful information to the image, it diminishes the contrast (outer shell)

A

Compton scatter

25
Q

What happens to PE and Compton as we increase kVp?

A

PE absorption decreases sharply
Compton scatter remains proportionally greater

26
Q

What would a high Z# part look like on a good radiograph?

A

It would appear white

27
Q

matter per unit volume (or the compactness of the atomic particles composing the anatomic part) also affects the amount of beam attenuation

A

Tissue density

28
Q

Increasing density = ________ attenuation & absorption, ________ transmission

A

increases, decreases

29
Q

Decreasing density = ________ transmission, ________ attenuation & absorption

A

increases, decreases

30
Q

The atomic number of the anatomic part and its tissue density affect _____ _____ _________

A

x-ray beam attenuation

31
Q

Bone attenuates x-ray beam more than _______

A

muscle

32
Q

Muscle attenuates the x-ray beam more than ______

A

fat

33
Q

Fat attenuates the x-ray beam more than _____

A

air

34
Q

the thicker the atomic part, the more x-rays are needed to produce a radiographic image

A

Tissue thickness

35
Q

Increasing thickness = _______ attenuation & absorption, _______ transmission

A

increases, decreases

36
Q

Decreasing density = _______ transmission, _______ attenuation & absorption

A

increases, decreases

37
Q
  1. incident photon interacts with an K or L shell electron, gives all of its energy to the ejected electron, photon is absorbed
  2. Ejected electron imparts atom with energy equal to excess binding energy
  3. The vacancy in K or L shell is filled by an electron from the next orbital shell (cascade effect)
  4. As electron drops to fill the void is sheds its excess energy as a secondary photon
A

photoelectric effect

38
Q
  1. Photon ejects outer shell electron
  2. The ejected electron leaves atom with equal energy to the excess imparted by the photon
  3. The photon continues on an altered path, with less energy (longer wavelength) than before collision
A

compton effect

39
Q

Comes from excess energy shed by electron dropping to fill void of inner orbital shell

A

secondary photon

40
Q

half value layer (HVL)

A

For every 4-5 cm of tissue, the number of photons decreases by half

41
Q

comes from scattered photons from the compton effect, diminishes contrast

A

Image fog
Unwanted exposure to the image receptor

42
Q

When the attenuated x-ray beam leaves the patient, is composed of both transmitted and scattered radiation

A

Remnant radiation (exit)

43
Q

the invisible image that exists on the exposed film before it is chemically processed

A

latent image

44
Q

is the visible image on the exposed film after processing

A

Manifest image

45
Q

dynamic imaging of internal structures can be visualized with a/an:
a. film-screen
b. projection image
c. spot film
d. fluoroscopy

A

d. fluoroscopy

46
Q

total absorption of the incoming x-ray photon is the result of the photoelectric effect
a. true
b. false

A

a. true

47
Q

which of the following will decrease beam attenuation?
a. increased tissue density
b. lower kilovoltage
c. higher z#
d. higher kilovoltage

A

d. higher kilovoltage

48
Q

contrast resolution is the ability of the imaging system to represent 2 different structures with the same level of gray
a. true
b. false

A

b. false

49
Q

the spatial resolution of a digital image is determined by the pixel size
a. true
b. false

A

a. true

50
Q
A

2403 Physics (8 decks)

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