Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics 2 > C1A: Transducer Evolution > Flashcards

C1A: Transducer Evolution Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Did old static scanners used one or multiple crystals? And what shape was the crystal?

A

One crystal which was disc shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Do modern days probes use a single or an array of crystals?

A

An array of multiple crystals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How was the sound steered in early probes?

A

It was mechanically steered (the crystal had to rotate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Is the focal zone fixed for mechanical transducers?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the names of the earliest probe technology where the crystal was mechanically moved across a track?

A

Linear translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe a wobbler probe?

A

A wobbler probe has a fixed element on a motor that rotates back and fourth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of image does a wobbler probe produce?

A

Sector type image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the main downside of the construction of a wobbler probes?

A

They were filled with fluid and the moving parts produced air bubbles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

With mechanical transducers what are the two items you can’t change?

A

Frequency

Focus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do mechanical probes obtain a linear FOV?

A

By using a reflector or acoustic mirror to direct sound into the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does an oscillating mirror probe work? What about oscillating element

A

It has a mirror that moved and a stationary element… opposite for oscillating element

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do rotating wheel probes work?

A

They have several crystals that spin and only pulse when the element passes the FOV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why was the annular array probe one of the biggest advances in probe technology?

A

You had the ability to change the focus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How was an annular array probes steered?

A

Mechanically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How are annular array probes constructed?

A

It uses concentric discs to allow focusing of the beam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does firing the different consecutive layers of an annular array probe effect the focus?

A

The wider the diameter of the concentric layer, the deeper the focal point and vice versa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are annular array probes focused?

A

Electronically

But they’re still mechanically steered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is one of the most significant problems with annular array probes?

A

The production of grating lobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are grating lobes called in mechanical probes?

A

They’re called side lobes and occur due to radial vibration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are grating lobes caused by in annular away probes?

A

Caused by length and width vibration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are grating lobes?

A

low energy beams that radiate away from the main axis and contribute to artifacts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is the element arranged in electronic array probs?

A

They have many small elements aligned in a linear row

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the two main types of arrays?

A

Phased array and Phased linear array

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is phasing?

A

Phasing is using nanosecond time deals to change when the voltage stimulate the crystal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Whats the purpose of phasing?

A

allows for beam focusing and steering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Whats another term that describes steering the sound beam?

A

Vector Scanning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How will an unsteered beam travel in comparison to a steered beam?

A

The unsteered beam will travel in a straight line, the steered beam with be angled one way or another.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What determines which way the beam angles?

A

Whichever side of the probe is stimulated first, the sound will travel away from the side (e.g. if L side is stimulated first, the beam will travel to the R side)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How are the elements fired in a sector phased array probe?

A

All crystals are fired at nearly the same time to steer the beam across the face of the probe

30
Q

What is the range of the FOV for the sector phased array probes?

A

90-30 degrees

31
Q

Approximately how many crystals does a sector phased array probe have?

A

~128

32
Q

Approximately how many crystals does a linear array probe have?

A

~64-200 elements arranged in a row

33
Q

What shape is the FOV for a linear array probe?

A

Rectangular but can also be trapezoidal if scanning in vector mode

34
Q

Do linear array probes have scan line divergence?

A

No

35
Q

Are linear array probes associated with higher or lower frequencies?

A

Higher

36
Q

Why is it bad to fire only a single element when scanning?

A

Firing a small source results in more divergence which causes a broad beam.
A broad beam gives poor resolution and sensitivity (specifically, we have poor lateral resolution)

37
Q

Does firing a single element effect our ability to focus and steer the beam?

A

Yes, it takes the ability away completely

38
Q

What is our overall field of view composed of?

A

Each individual scan line firing

39
Q

What effect does firing multiple elements in a group or segment result in?

A

A larger group means less divergence so better resolution (lateral) and sensitivity.
It also allows us to steer and focus the beam electronically.

40
Q

What is the downside of fining multiple elements in a group of segment?

A

We have fewer scan lines which reduces spatial resolution and can cause gaps between beams

41
Q

How do we fix gaps caused by firing elements in groups?

A

We use segmental sequencing

42
Q

How does segmental sequencing work?

A

We fire a group of crystals to create a beam and then we fired a second group which is only one crystal down the row.
This causes the beams to overlap so their are no empty spaces between the beams

43
Q

How are the crystals in a curved linear array probe different than a linear array probe?

A

It‘s rectangular shaped elements are curved on one end instead of flat

44
Q

What is the advantage of a curved linear probe?

A

It has a large footprint and FOV and has good near field and far field resolution

45
Q

What are the disadvantages of a curved linear probe?

A

Resolution in the far field can be degraded as the distance between beams in increased

46
Q

How do we correct for grating lobes?

A

Apodization

47
Q

What is apodization?

A

A process in which the voltages of the crystals are gradually weakened from inner to outer… this reduces cross talk
(e.g. outside crystals dont ring as much as the inner ones)

48
Q

What are the two ways to obtain 3D and 4D images?

A

Freehand, using a traditional array probe
AND
Volumetric probe

49
Q

How do volumetric probes work?

A

The beam is swept over the area of interest to get in info needed for 3D/4D (can be mechanically or electronically swept)

50
Q

How are 1.5D probes different than 1D probes?

A

1.5D probes allow you to focus the beam in the x, y AND z planes which reduce artifacts (especially beam width artifacts) and improves the image

51
Q

How are the elements arranged in 1.5 D probes?

A

There are 3 rows of crystals

52
Q

1D probes are used for what type of scanning?

A

2D

53
Q

What kind of backing to CW probes have? And what kind of voltage do they use?

A

They’re air backed and have a continuous AC driving voltage

54
Q

What is the ‘focal zone’ or sample volume for CW?

A

Zone of sensitivity

55
Q

What type of bandwidth is associated with electronic array probes?

A

Wide bandwidth

56
Q

What limits the number of frequencies that be can drive the probe to ring at?

A

The size of the bandwidth and attenuation

57
Q

What type of frequencies are too weak to be detected by the probe?

A

Any frequencies that have an amplitude of less than half of the resonance frequency

58
Q

What is another name for the usable bandwidth?

A

The 6 dB bandwidth

59
Q

When referring to bandwidth, what value is equal to half of the amplitude or 1/4 the intensity of the resonant frequency?

A

6 dB

60
Q

A drop in what number is equal to a reducing of half the amplitude?

A

6 dB

61
Q

Whats the equation for fraction bandwidth?

A

FB= Bandwidth/Frequency

62
Q

A probe with a faction bandwidth of what value is considered to be a broadband design?

A

80%

63
Q

What is another term to describe bandwidth?

A

Quality Factor or Q factor

64
Q

What is the equation for Q factor?

A

Q= Frequency/Bandwidth

65
Q

What kind of Q factor do we want for 2D scanning? And for Doppler?

A

Low Q factor for 2D (because we want a short pulse and a wide bandwidth)
High Q factor for Doppler (because we want a long pulse and a narrow bandwidth)

66
Q

Whats the relationship between pulse length and bandwidth?

A

Inverse

Short pulse = wide bandwidth
Long pulse = narrow badwidth

67
Q

Whats the relationship between bandwidth and Q factor?

A

Inverse

68
Q

Modes requiring more sensitivity (CW Doppler) will have what type of bandwidth?

A

Narrow bandwidth (which means higher Q factor)

69
Q

2D probes are used for what type of scanning?

A

3D and 4D

70
Q

What happens to the focal point if the outer crystals of a probe are fired before the inner crystals?

A

The focal point will be closer to the probe

71
Q

What are two distinct qualities of a vector probe?

A

1) they are capable of expanding the probes field of view

2) they allow the operator to steer the Doppler colour box

72
Q

Does segmental sequencing increase the number of scan lines we’re sending out

A

Yes

Physics 2 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions