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Phys 254 > Module 1: Transducer Evolution > Flashcards

Module 1: Transducer Evolution Flashcards

1
Q

Old static B scanners and early real time units used how many crystals?

A

One

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2
Q

Some of the earliest probes were very basic in designed with what?

A
  1. A single disc element housed
  2. These probes were mechanically steered to obtain the field of view and were prone to breakdown
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3
Q

What was the evolution of the transducer?

A

Started from a single disc crystal > Mechanically steered > Electronic array

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4
Q

What kind of element does mechanical transducers have?

A

Thin disk shaped crystal 6-19 mm in diameter

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5
Q

Mechanical transducers have fixed focal zones with varying configuration such as

A
  1. Linear translation
  2. Wobbler
  3. Oscillating element
  4. Oscillating mirror
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6
Q

Linear translation is the oldest technology and simply moved how?

A

It moved the crystal assembly along a track to “sweep” the tissue

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7
Q

The wobbler probe fixed an element onto what?

A

Onto a motor that rotated back and forth to obtain the field of view

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8
Q

What kind of image did the wobbler probe produce?

A

Sector type image

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9
Q

The wobbler probe images were fluid filled and the moving parts risked the production of what?

A

Air bubbles

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10
Q

To achieve a linear Field of view, probes will use what?

A

A reflector or acoustic mirror to direct the sound into the patient

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11
Q

With the oscillating mirror, what is the difference?

A

It is the mirror that moves with a stationary element

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12
Q

What is the rotating wheel probe?

A

It has several crystals that spin and only pulse when the element passes the field of view

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13
Q

What is the annular array?

A

Uses concentric discs to allow for focusing of the beam

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14
Q

During the annular array, what happened when you change the disc that is fired?

A

You change the diameter which in turn varies the focal depth

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15
Q

The annular array still had the same limitations as what?

A

The mechanically steered
such as the production of grating lobes

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16
Q

In annular arrays what does the diameter of the crystal do?

A

Changes the focal depth

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17
Q

What did annular probes prove?

A

A probe with no moving parts was evident

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18
Q

Array probes are arranged how?

A

Multiple small elements aligned in linear rows

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19
Q

The two main types of arrays we will discuss are what?

A
  1. Phased sector array
  2. Phased Linear array (including the curved array)
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20
Q

Electronic array probes tend to have what kind of bandwidth? And why?

A

Wide bandwidth and need to have the flexibility to perform other applications such as
1. Colour/ spectral doppler
2. M mode
3. Power doppler

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21
Q

What is phasing?

A

Uses nanosecond time delays to change when the voltage excites the crystal

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22
Q

What is the purpose of phasing?

A

Allows use to control the beam and allow for beam focusing and steering

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23
Q

Focusing and steering are accomplished with what in electronic array probes?

A

Phasing of the voltages to the crystal in the electronic array probes

24
Q

Steering of the beam can help with what?

A

Steering of the beam can help direct the sound out at an angle as is the case for the phased sector array, Doppler and vector scanning

25
Q

What is another term for describing steering the beam?

A

Vector scanning

26
Q

A good way to determine the direction of the beam is to assess what?

A

The slope of the delayed voltages

27
Q

What is the FOV for phased array?

A

Can be as large as 90 degrees or as small as 30 degrees

28
Q

What was the intention of phased array sector?

A

For the thought of scanning through the ribs as the reason for the shape

29
Q

For a phased array probe how does it work?

A

All crystals (approx 128) are fired nearly at the same time to steer the beam across the face of the probe

30
Q

What kind of footprint does the linear array have?

A

Tended to have relatively large footprint with approximately 64-200 elements arranged in a row

31
Q

What is the FOV for a linear array probe?

A

It is a rectangular shape but can be trapezoidal if scanning in a vector mode

32
Q

What does the FOV for linear array probes mean?

A

There is no scan line divergence

33
Q

What were some of the applications of the linear array probe?

A

They tended to be used for exams associated with higher frequencies

34
Q

Firing a single element will increase what? This will result in what?

A

It will increase divergence which equates to a broad beam resulting in poor resolution and sensitivity

35
Q

Firing a single element takes away around ability to do what?

A

Electronically focus or steer the sound

36
Q

The larger point source of sound would have what?

A

Less divergence and the resolution would improve as would the sensitivity

37
Q

Firing in segments also enables what?

A

Electronic transmit focusing and steering

38
Q

Having a larger point source or firing in segments has many benefits but at the cost of what?

A

Fewer scan lines which can degrade the images spatial resolution

39
Q

What is segmental sequencing?

A

A group of crystals is fired to create a beam followed by a second group that is one crystal down in the row

40
Q

The curved linear probe uses what kind of principles?

A

Similar to the linear array

41
Q

What kind of elements are used in the curved linear probe?

A

Small rectangular shaped elements that are curved rather than straight

42
Q

What is the major advantage of the curved linear probe?

A

Large footprint and FOV
** this means we see well in the near and far field**

43
Q

What is the disadvantage of the curved linear probe?

A

The resolution in the far field can be degraded as the distance between beams is increased

44
Q

Crystals can ring in an undesirable way along the length and width, This has the potential of creating what?

A

Off axis sound beams called grating lobes that will produce artifacts on the image

45
Q

What is apodization?

A

Voltages to crystals are gradually weakened from the inside out

46
Q

Obtaining 3D and 4D images can be done in two ways what are they?

A
  1. Freehand using a traditional array probe
  2. Volumetric probe
47
Q

How can we obtain 3D and 4D images using volumetric probe?

A

Beam is swept over the area of interest (electronically or mechanically) to obtain the information for 3D reconstruction

48
Q

Intravascular probes are capable for scanning what?

A

The Lumen of a vessel

49
Q

What does a transesophageal echo probe do?

A

Probe that can help improve the visualization of the heart

50
Q

What does the 1.5 probe do?

A

Allows us to focus in the Z axis

51
Q

There are many specialty probes that exist for things like what?

A
  1. Biopsies
  2. Interventions
  3. Endocavitary exams
52
Q

Transesophageal echo probes (TEE) can do what?

A

Improve visualization of the heart

53
Q

Dedicated CW probes contain two crystals, what does each crystal do?

A

One transmits and the other receives

54
Q

The two crystal CW probes are air backed and have what?

A

Continuous AC driving voltage

55
Q

What is the pencil probe?

A

CW probes that contain two crystals that are air backed and have a continuous A driving voltage.

56
Q

What is the pencil probe also referred to as?

A

Ped-off probe

Phys 254 (19 decks)

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