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SONOGRAPHY CORE Exam Prep > Construction and Operation of Transducers > Flashcards

Construction and Operation of Transducers Flashcards

1
Q

Transducers convert what two types of energy?

A

Electric energy to pressure energy

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2
Q

What is it called when crystals are heated to about 350 degrees celsius and then cooled down to allow elements to compress and expand?

A

Curie point

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3
Q

What is operating frequency also called?

A

Resonance frequency

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4
Q

T or F? The operating frequency is different between PW and CW?

A

True

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5
Q

In CW, the operating frequency is determined by what?

A

The driving voltage

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6
Q

In PW, the operating frequency is determined by what?

A
  1. Propagation speed
  2. Crystal thickness
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7
Q

What is the formula between crystal thickness and operating frequency is PW?

A

Operating frequency = 1/thickness (inversely proportional)

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8
Q

When crystal thickness is increased, what happens to frequency?

A

Decreases - longer period/wavelength

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9
Q

When crystal thickness is decreased, what happens to frequency?

A

Increases - shorter period/wavelength

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10
Q

What is the equation to determine operating frequency in terms of crystal thickness?

A

F (o) = c / (2x crystal thickness)

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11
Q

What type of resolution is improved with harmonics?

A

Lateral resolution (detail resolution)

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12
Q

Benefits of damping material on a transducer?

A

Decreases SPL (# cycles x wavelength)

Decreases PD (#cycles x period)

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13
Q

What element of a transducer decreases the number of cycles in a pulse?

A

Damping material

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14
Q

Does damping material increase or decrease the bandwidth?

A

Increases / broadens bandwidth

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15
Q

What type of resolution is improved with damping material?

A

Axial and spatial

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16
Q

Disadvantages of damping material?

A

Efficiency and specificity

17
Q

The matching layer thickness is how much of the wavelength of sound leaving the transducer?

A

1/4 of the wavelength

18
Q

Using ultrasound gel gives rise to what transducer element?

A

Matching layer - improves transmission

19
Q

What element on the transducer minimizes the acoustic impedance mismatch between transducer crystals and patient tissue?

A

Matching layer

20
Q

What does CMUT stand for ?

A

Capacitative Micromachined Ultrasound Transducers

21
Q

The area where the ultrasound beam CONVERGES is known as?

A

Natural focus

22
Q

What is the near zone also called?

A

Fresnel zone

23
Q

Beam width decreases with increasing distance from the transducer is called?

A

Near zone

24
Q

What is the far zone also called?

A

Fraunhofer

25
Q

Beam width increases with increasing distance from the transducer is called?

A

Far zone

26
Q

The NZL is also called the?

A

Focal length

27
Q

What 2 things is the NZL determined by?

A
  1. Operating frequency
  2. Size of aperture
28
Q

When frequency increases, what happens to NZL?

A

Increases

29
Q

When aperture increases, what happens to NZL?

A

Increases

30
Q

Formula to calculate NZL?

A

[D^2 x operating frequency] / 6

31
Q

What happens to the NZL when you double the size of the aperture?

A

Increase by a factor of 4 since it is (D^2)

32
Q

What happens to NZL when you double the frequency?

A

Increases by a factor of 2

33
Q

Beam focus improves what resolution?

A

Lateral (detail)

34
Q

What is the focal length?

A

Distance from transducer to focal region

35
Q

What is the formula to calculate intensity?

A

Power/Area

36
Q

Where is the HIGHEST intensity of the beam in terms of the focus?

A

Just before the focus

37
Q

Where is lateral resolution best?

A

AT or just before focal zone

38
Q

Where should you place the focus to yield the best lateral resolution?

A

Just below the area of interest

39
Q

What resolution is improved with multiple focuses?

A

Lateral

SONOGRAPHY CORE Exam Prep (16 decks)

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