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Sonographic Topics > Chapter 2: Ultrasound Transducers > Flashcards

Chapter 2: Ultrasound Transducers Flashcards

1
Q

element that generates electricity when pressure is applied to it and that changes shape when electricity is applied to it

A

piezoelectric element

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2
Q

most commonly made piezoelectric element material

A

lead zirconate titanate

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3
Q

the actual transducer inside the scanhead

A

crystal or element

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4
Q

temperature at which material will obtain piezoelectric properties

A

Curie Point

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5
Q

Transducers are ___-sterilized

A

cold

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6
Q

frequency is related to two factors

A

thickness of the piezoelectric element
propagation speed of element

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7
Q

________ is the primary determinant of resonating frequency of transducer

A

thickness of the element

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8
Q

A thicker element will produce a _____ frequency

A

lower

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9
Q

A thinner element will produce a _____ frequency

A

higher

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10
Q

resonating frequency is typically between __-__ MHz

A

2
15

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11
Q

if the transducer sends out a pulse before it receives the last one, it is unable to recognize where the echo originated, and therefore, cannot display it correctly on the monitor

A

depth ambiguity

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12
Q

waves that, when stacked, have matching peaks and troughs; undergo constructive interference

A

in phase waves

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13
Q

waves that, when overlapped, are opposite of each other; undergo destructive interference

A

out of phase waves

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14
Q

tiny point sources of sound on transducer

A

wavelet

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15
Q

wavelets create a propagating sound wave whose direction of travel is perpendicular to wavefront, which is line tangential to all the wavelets

A

Huygen’s principle

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16
Q

The ultrasound machine produces between __ and ___v in order to drive piezoelectric elements

A

10
500

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17
Q

lies between element and patient’s skin

A

matching layer

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18
Q

steps down the impedance from that of the element to the patient’s skin

A

matching layer

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19
Q

has an impedance value between matching layer and patients skin

A

coupling gel

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20
Q

sits on back of transducer behind the elements; provide damping of piezoelectric element; composed of an epoxy resin loaded with tungsten

A

backing material/damping material

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21
Q

decreases number of cycles in a pulse, effectively decreasing spatial pulse length

A

backing material/damping material

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22
Q

The backing material shortens the pulse to __-__ cycles per pulse.

A

2
3

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23
Q

ability to detect weak returning echoes

A

sensitivity

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24
Q

Damping material ______ sensitivity

A

decreases

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25
Q

The more damping there is, the ______ the pulse and the _____ the bandwidth

A

shorter
wider

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26
Q

term used to quantitate the purity of the beam

A

Quality factor

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27
Q

operating frequency divided by the bandwidth

A

quality factor

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28
Q

Pulsed wave transducers have ____ Q-factors

A

low

29
Q

Continuous wave transducers have ____ Q-factors

A

high

30
Q

all the scan lines placed next to each other

A

frame

31
Q

Two methods for sending out scan lines

A

electronic scanning
mechanical scanning

32
Q

performed with transducers that have multiple active elements

A

electronic transducers

33
Q

system can selectively excite the elements as needed to shape and steer the beam; no motors needed for beam steering, may be either sequenced or phased, can produce various image shapes

A

electronic transducers

34
Q

often used in vascular or small parts; rectangular image; elements arranged in a line, next to each other, but are fired in small groups in sequence; beam can be electronically steered

A

linear sequenced array

35
Q

elements fired in groups, curve-shaped image, abdominal and ob/gyn

A

curved sequenced array

36
Q

other names for linear sequenced array

A

linear sequential array
linear array

37
Q

other names for curved sequenced array

A

convex
curvilinear
curved sequential array

38
Q

more commonly known as sector or vector array; small footprint; used for cardiac imaging, neonatal brain imaging, some endocavity transducers; electronic steering needed for every scan line; sector shaped or “pie” shaped;

A

phased arrays

39
Q

flat topped trapezoidal image shape; all the scan lines originate from a common point of origin; uses phasing to steer and focus the beam

A

vector array

40
Q

changing the timing of shocking of the elements in order to shape and steer the beam

A

phasing

41
Q

3 different ways to create a 3D image

A

freehand technique
mechanical technique
2D transducer or matrix array

42
Q

acquire real time volumes using transducers with up to ______ elements

A

10,000

43
Q

There are ___-____ elements in a standard 1D array

A

128
512

44
Q

contains two piezoelectric elements

A

continuous wave

45
Q

Continuous wave has no _____ resolution

A

range

46
Q

the ability of a system to distinguish between closely spaced objects

A

spatial resolution

47
Q

Resolution is divided into four different components:

A

axial
lateral
elevational
contrast

48
Q

minimum distance between two reflectors can be parallel to the beam, and still appear as two dots on the screen

A

axial resolution

49
Q

LARRD

A

longitudinal
axial
radial
range
depth

50
Q

The shorter the pulse used, the _____ the axial resolution

A

better

51
Q

Axial resolution is = to

A

1/2 of SPL

52
Q

relates to the width of the beam and reflectors that lie perpendicular to it

A

lateral resolution

53
Q

LATA

A

lateral
azimuthal
transverse
angular

54
Q

diameter of a beam determined by both frequency and diameter of element itself; takes on shape of hourglass appearance

A

aperture

55
Q

narrowest point of beam

A

focal point

56
Q

region from transducer face to focal point

A

near zone or fresnel zone

57
Q

length of near zone

A

near zone length

58
Q

region distal to focal point

A

far zone or fraunhofer zone

59
Q

spreading out of beam

A

divergenice

60
Q

Natural focus zone; lateral resolution varies with depth

A

unfocused transducers

61
Q

shorter NZL, more divergence in far field

A

smaller aperture

62
Q

third dimension of beam

A

elevational resolution

63
Q

resolution in third dimension of beam, thinnest plane optimal, fixed focusing

A

elevational resolution

64
Q

ability to distinguish between different shades of gray

A

contrast resolution

65
Q

represents time, ability to display structures in real time; relates to how quickly frames are generated; also known as frame rate

A

temporal resolution

66
Q

frame rate units

A

Hz, frames per second

67
Q

PRF is ______ related to frame

A

directly

68
Q
A

Sonographic Topics (35 decks)

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