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SPI > Transducers Edelmen > Flashcards

Transducers Edelmen Flashcards

1
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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2
Q

Pzt materials change shape when a voltage is applied to them

A

Reverse piezoelectric effect

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3
Q

Materials which convert sound into electricity and vise versa are called

A

Piezoelectric/ ferroelectric

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4
Q

Man made transducers

A

Pzt

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5
Q

Protects the internal components of the transducer from damage and insulated the patient from electrical shock

A

Case

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6
Q

Prevents spurious electrical signals in the air from entering the transducer. Prevents electrical noise from contaminating the clinicals important electrical signals

A

Electrical shield

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7
Q

Prevents vibrations in the case from inducing an electrical voltage in the Pzt of the transducer. Isolates or uncouples the internal components of the transducer from the case

A

Acoustic insulator

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8
Q

Shaped like a coin. Characteristics of the sound beam emitted by the transducer are related to the dimensions of the active element

A

Pzt or active element

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9
Q

Electrical connection between the Pzt and us system. Active element require electrical contact so during transmission the voltage can cause the crystal to vibrate and produce an ultrasonic wave

A

Wire

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10
Q

Positioned in front of the Pzt at the face of the transducer. Protects the active element and increases the efficiency of sound energy transfer between the active element and the body

A

Matching layer

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11
Q

Back of the active element and reduces the ringing of the Pzt. Made of epoxy resin with tungsten filaments. It enhances axial resolution

A

Backing material / damping element

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12
Q

Decreasing order of impendance

A

PZT > matching layer > gel > skin

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13
Q

Thickness of the matching layer

A

1/4 wavelength thick

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14
Q

Thickness of active element

A

1/2 wavelength thick

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15
Q

3 consequences of backing material

A

decreased sensitivity, wide bandwidth, low quality factor

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16
Q

Less able to convert low level sound reflections into meaningful electrical signals

A

Decreased sensitivity

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17
Q

Range of frequencies in a pulse. Difference between the highest and lowest frequencies

A

Bandwidth

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18
Q

Long duration events have what type of bandwidth

A

narrow

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19
Q

unitless number that is inversely related to bandwidth. main frequency divided by the bandwidth

A

Quality factor

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20
Q

A short, dampened pulse has a ___ Q factor

A

lower

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21
Q

Q factor and bandwidth are ____ related

A

inversely

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22
Q

Destruction of all microorganisms by exposure to extreme heat, chemical agents, or radiation

A

Sterilization

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23
Q

Application of a chemical agent to reduce or eliminate infectious organisms on an object.

A

Disinfection

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24
Q

Transducers should be disinfected with

A

Cidex or other cold germicides

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25
Q

Backing material ___ duty factor and _____ quality factor

A

decreases

26
Q

Characteristics of high frequency PW imaging transducers

A

Thinner Pzt crystals & Pzt with higher speeds

27
Q

Characteristics of low frequency PW transducers imaging transducers

A

Thicker PZT crystals and lower speeds

28
Q

Terms describe the shape and regions of a sound beam

A

Focus
Near zone
Focal length / near zone length
Far zone
Focal zone

29
Q

Location where the beam is the narrowest

A

Focus / focal point

30
Q

Region from the transducer to the focus

A

Near field / fresnel zone

31
Q

Distance from the transducer to the focus

A

Focal length / focal depth / near zone length

32
Q

Region that starts at the focus and extends deeper

A

Far zone / far field / Fraunhofer zone

33
Q

Region around the focus where the beam relatively narrow

A

Focal zone

34
Q

At the transducer the beam diameter equals

A

Transducer diameter

35
Q

At the focus the beam diameter is

A

1/2 transducer diameter

36
Q

A 2 near zone lengths, the beam diameter

A

Equals transducer diameter

37
Q

Deeper than 2 near zone lengths the beam diameter is

A

Wider than transducer diameter

38
Q

What characteristics of a fixed focus transducer determine the focal depth

A

Tranducer diameter and frequency of sound

39
Q

A smaller diameter Pzt and low frequency creates a ____ focus

A

Shallow

40
Q

What transducers is steered by a motor or reflecting mirror

A

Mechanical and annular phased array transducer

41
Q

4 transducers that focus the us beam electronically

A

Linear switched array, linear phased array, annular phased array, and convex/curvilinear array

42
Q

The minimum number of active elements in a mechanical transducer is

A

1

43
Q

Describe a linear phased array transducer

A

rectangular, 1/2 to 1/4 wavelength wide

44
Q

How are the pzt crystals of a linear phased array fired

A

At almost exactly the same time

45
Q

Describe a linear sequential array transducer

A

rectangular, 1 wavelength wide

46
Q

What component of an ultrasound system is made of lead zirconate titanate

A

Transducers active element

47
Q

How thick is an active element of a 3 mhz pw transdcuer

A

Half the wavelength of the sound wave in the pzt

48
Q

What component of the transducer is made from a slab of epoxy embedded with tungsten particles

A

Damping material

49
Q

Impedance from highest to lowest

A

PZT, matching layer, gel, skin

50
Q

Impedance from lowest to highest

A

skin, gel, matching layer, pzt

51
Q

How thick is the matching layer of a 2 mhz pw transducer

A

one quarter the wavelength of sound in the matching layer

52
Q

The spatial pulse length ___ with backing material

A

decreases

53
Q

To calculate bandwidth

A

highest frequency - lowest frequency

54
Q

Damping material ____ sensitivity

A

decreases

55
Q

What helps determine the frequency of the sound produced by the transducer of a cw us system

A

US system electronics. It has nothing to do with the crystals thickness and speed

56
Q

2 characteristics to determine the frequency of sound in a pulse

A

Thickness and speed of the active element

57
Q

Characteristics of a high emitted acoustic wave frequency

A

Thin element and high prop speed

58
Q

the higher the frequency the length of the near zone will be

A

longer

59
Q

____ diameter and ____ frequency will have a deep focus (long near zone)

A

large diameter and high frequency

60
Q

3 terms to describe a shape of a sound created by a tiny fragment of pzt

A

Spherical, huygens wavelet, and V shaped

SPI (16 decks)

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