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Phys 254 > Module 4: Resolution > Flashcards

Module 4: Resolution Flashcards

1
Q

Resolution can be broken down into what three aspects?

A
  1. Detail
  2. Contrast
  3. Temporal
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2
Q

Detailed resolution can be further divided in what three aspects?

A
  1. Axial
  2. Lateral
  3. Elevational
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3
Q

What is axial resolution?

A

The ability to separate reflects along the path of the beam

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4
Q

Axial resolution is dependent of what? and is calculated how?

A

Dependent of SPL and is calculated by 1/2 the SPL

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5
Q

What is the formula for spatial resolution?

A

AR = (1/2) SPL

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6
Q

If SPL decreases what happens to axial resolution?

A

It improves

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7
Q

Axial resolution is known by what of the following names?

A
  1. Longitudinal
  2. Range
  3. Depth

Remember LARD

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8
Q

What is lateral resolution?

A

The ability to separate reflectors perpendicular to the path of the beam

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9
Q

Lateral resolution is dependent of what?

A

The width of the beam and therefore, is not constant with depth

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10
Q

What does this image represent?

A

Lateral resolution

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11
Q

Lateral resolution is directly related to what?

A

The width of the beam

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12
Q

If the beam width decreases then what?

A

Lateral resolution improves

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13
Q

Lateral resolution is known by what other names?

A
  1. Angular
  2. Transverse
  3. Azimuthal

Remember LATA

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14
Q

What is elevational resolution?

A

Also known as slice thickness this is the ability to separate reflectors perpendicular to the image plane of the beam

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15
Q

Elevational resolution is dependent on what aspect of the beam?

A

Width of the beam but in Z axis

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16
Q

Elevational resolution is directly related to what?

A

The width of the beam in the Z axis

17
Q

If beam width in the Z axis decreases then what happens?

A

Elevational resolution improves

18
Q

Elevational Resolution is also known as what?

A

Slice thickness

19
Q

What is contrast resolution?

A

The ability to distinguish subtle differences in tissue gray scale

20
Q

What is contrast resolution related to?

A

Bit depth

21
Q

For contrast resolution, having a higher bit depth means what?

A

The more shades of tray the system is capable of displaying

22
Q

More shades of gray gives the operator what?

A

More control over the dynamic range

23
Q

By reducing the dynamic range the sonographer may increase the ability to do what?

A

Distinguish once subtle differences in grayscale

24
Q

What is temporal resolution?

A

The ability to appreciate moving structures in real time

25
Q

What is temporal resolution related to?

A

System frame rate

26
Q

Temporal resolution is directly related to what?

A

Frame rate

27
Q

If frame rate increases then what happens?

A

Temporal resolution improves

28
Q

Since temporal resolution is defined by frame rate, what else is frame rate related to?

A

PRF

29
Q

What is the formula for temporal resolution?

A

PRF(Hz) = n x LPF x FR(Hz)

n = number of foci
LPF = lines per frame
FR = frame rate or frames per second

30
Q

Penetration of sound plays an important role in what?

A

PRF

31
Q

What is the formula for sound penetration?

A

Penetration (cm) x n x LPF x FR < 77,000 cm/s

32
Q

Why do we use 77,000 for penetration of sound?

A

Because it represents half the average speed of sound in soft tissue (154,000 cm/s)

33
Q

What things relate to better axial resolution? 5

A
  1. Higher frequency probes
  2. Wide bandwidth
  3. Decreased wavelength
  4. Increased damping
  5. Low Q factor
34
Q

What things relate to better lateral resolution?

A
  1. Distance from the probe
  2. Amount of focusing
  3. Size of aperture
  4. NZL
  5. Higher the frequency
35
Q

What things relate to better elevational resolution?

A
  1. Distance from the probe
  2. Higher the frequency
  3. NZL
  4. Amount of focusing in the Z plane
36
Q

What things relate to better temporal resolution? 5

A
  1. Depth of penetration
  2. The number of foci
  3. The sector width
  4. Frame rate
  5. The number of lines per frame

Phys 254 (19 decks)

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