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Ultrasound Physics > Chapter 8 > Flashcards

Chapter 8 Flashcards

Transducers

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1
Q

Any device that converts one form of energy into another

A

Transducer

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2
Q

Transmission

A

Reverse Piezoelectric Effect

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3
Q

Reception Piezoelectric

A

Piezoelectric Effect

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4
Q

Electrical energy from the system is converted into sound

A

Transmission, Reverse Piezoelectric effect

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5
Q

The reflected sound pulse is converted into electricity

A

Reception, Piezoelectric effect

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6
Q

Piezoelectric materials change shape when a voltage is applied to them, called

A

Reverse Piezoelectric effect

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7
Q

—– describes the property of certain materials to create a voltage when they are mechanically deformed or when pressure is applied to them.

A

Piezoelectric effect

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8
Q

Piezoelectric is also known as

A

Ferroelectric

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9
Q

Commonly used in clinical transducers

A

Lead zirconate titanate or PZT

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10
Q

Synonyms for PZT

A

Ceramic, Active element, Crystal

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11
Q

Positioned in front of the PZT at the face of the transducer

A

Matching layer

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12
Q

One half wavelength thick

A

PZT or active element

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13
Q

one quarter wavelength thick

A

Matching layer

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14
Q

Increase the efficiency of sound energy transfer between the active element and the body, and protects the PZT

A

Macthing Layer

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15
Q

Crystal damping enhances what

A

Axial resolution

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16
Q

Bonded to the back of the active element, which reduces the ringing of the PZT

A

Backing Material or Damping Material

17
Q

Backing material is commonly made of what

A

Epoxy resin impregnated with tungsten filaments

18
Q

What prevents vibrations in the case from inducing an electrical voltage in the PZT of the transducer

A

Acoustic insulator

19
Q

Damping material do what to the SPL and Pulse duration

A

Shortens the SPL and Pulse duration

20
Q

What are the characteristics of damping material

A
  1. High degree of sound absorption
  2. Acoustic impedance aimilar to PZT
21
Q

3 consequences related to using a backing material

A
  1. decreased sensitivity
  2. Wide Bandwidth
  3. Low Quality Factor
22
Q

The range of frequency in the pulse

A

Bandwidth

23
Q

The difference between the highest and lowest frequency.

A

Bandwidth

24
Q

Transport the voltage from the crystal of the transducer to the system for further processing

A

Wire

25
Q

The use of gel eliminates the — layer and facilitates sound transmission into the body

A

Air
PZT-Matching layer-gel-skin

26
Q

Increases the efficiency of the sound energy transfer between the active element and the body and protects the active element

A

Matching layer

27
Q

The matching layer is —- wavelength thick

A

one quarter wavelength thick

28
Q

Bonded to the back of the active element it reduces the ringing of the PZT

A

Backing Material
Damping material

29
Q

Backing material is made of what

A

Epoxy resin impregnated with tungsten filaments

30
Q

What restricts the extent of PZT deformation

A

Backing material

31
Q

What will the damping material do?

A
  1. Shortens the spatial pulse length and pulse duration,
  2. Improves image quality
    Short Pulses= higher image quality
  3. Decreases the transducer sensitivity
32
Q

What is the relation between Q-factor and bandwidth

A

Inversely related

33
Q

Formula for Q-factor

A

Main Frequency / bandwidth

34
Q

Shorter damped pulse has

A

Lower Q-factor

35
Q

Longer Undamped pulse has

A

Higher Q-factor

36
Q

A transducer produces a freq equal to its operating freq also called

A

Resonance Frequency

37
Q

Expose the PZT to strong electrical field while being heated to a substantial temp the process is called

A

Polarization

38
Q

The sound in PZT and the freq of the sound are

A

Directly related

Ultrasound Physics (11 decks)

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