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Physics C/O 2026 > Chapters 9-12 Santanna > Flashcards

Chapters 9-12 Santanna Flashcards

1
Q

As sound travels

A

the width of the beam changes

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2
Q

Narrow beams create

A

better images

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3
Q

the location at which the beams= reaches its minimum diameter

A

focus or focal point

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4
Q

the distance from the transducer to the focus

A

focal depth
focal length or near zone length

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5
Q

near zone (fresnel zone)

A

the zone between the transducer and the focus

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6
Q

far zone ( fraunhofer zone)

A

the zone deeper than the focus, beyond the near zone

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7
Q

sound beams ____ in the near zone

A

coverge

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8
Q

sound beams ___ in the far zone

A

diverge

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9
Q

what is focal zone

A

the region surrounding the focus where the beam is kind of narrow and the picture is relatively good

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10
Q

PZT diameter

A

transducer aperture (another name for the transducer diameter)

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11
Q

at the transducer

A

beam diameter equals transducer diamter

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12
Q

at the focus

A

beam diameter is one-half transducer diameter

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13
Q

at 2 near zone lengths

A

beam diameter equals transducer diameter

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14
Q

deeper than 2 near zone lengths

A

beam diameter is wider than transducer diameter

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15
Q

focal depth is determined by

A

transducer diameter and frequency of the ultrasound

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16
Q

shallow focus

A

small diameter, low frequency

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17
Q

deep focus

A

large diameter, high frequency

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18
Q

divergence of the beam describes

A

the spread of the sound beam in the deep far zone

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19
Q

less divergence

A

larger aperture, high frequency, narrower beam in far field, improved lateral resolution in the far field

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20
Q

more divergence

A

smaller aperture, low frequency, wider beam in far field, degraded lateral resolution in far field

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21
Q

frequency (CW) is determined by

A

electronic frequency

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22
Q

frequency (pulsed) is determined by

A

thickness in ceramic and speed of sound in ceramic

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23
Q

divergence

A

aperture of active element and frequency of sound

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24
Q

each tiny part of the surface of the transducer face may be considered

A

an individual sound source, this creates a huygens wavelet

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25
Q

when all of these wavelets combine, they create an hourglass shaped beam

A

huygens principle

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26
Q

axial resolution

A

the ability to distinguish two structures that are close to each other front to back, parallel to, or along the beam’s main axis

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27
Q

units of axial resolution
can it be changed by sonographer

A

distance, mm, cm
no

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28
Q

changing axial resolution means

A

changing transducers

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29
Q

SPL (mm) / 2

A

equation for axial resolution

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30
Q

Shorter pulses mean

A

shorter SPL and PD… meaning images are more accurate

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31
Q

axial resolution is BEST with

A

highest frequency and fewest number of cycles per pulse

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32
Q

axial resolution is WORST with

A

lower frequency and larger number of cycles per pulse

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33
Q

If we add more pulses, we

A

degrade our images

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34
Q

Better axial resolution

A

shorter SPL
shorter PD
higher frequencies
fewer cycles per pulse
lower numerical values

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35
Q

minimum distance that two structures are separated by side to side or perpendicular to the sound beam that will produce two distinct echoes

A

lateral resolution

36
Q

units for lateral resolution

37
Q

lateral resolution =

A

beams diameter

38
Q

lateral resolution varies with

A

depth
also known as beam width variation or point spread artifact

39
Q

lateral resolution is best at

A

focus or one near zone length from transducer bc this is where the beam is narrowest

40
Q

lateral resolution is ____ as axial resolution because sound waves are wider than they are short

A

not as usually good as

41
Q

In the far field, higher frequency pulsed sound has _____ beams

42
Q

higher frequency sound improves both axial and lateral resolution where?

A

in the far field only

43
Q

higher frequency improves

A

image detail

44
Q

LARRD

A

Longitudal
Axial
Range
Radial
Depth

45
Q

LATA

A

Lateral
Angular
Transverse
Azimuthal

46
Q

Focusing concentrates the sound energy into a ________ beam and thus ______ the lateral resolution

A

narrower and improves

47
Q

What are the three methods of focusing are

A

external focusing - using a lens
internal focusing - using a curved active element
phased array focusing- using the electronics of the ultrasound system

48
Q

Fixed focus transducers have

A

poor lateral resolution bc the depth cannot be adjusted

49
Q

Single crystal transducers

A

are always fixed focus

50
Q

what is the only display mode that provides info regarding reflector motion with respect to time?

51
Q

with A- mode, what is displayed on the x-axis?

A

depth of the reflector

52
Q

with m-mode, what is displayed on the y-axis?

A

depth of the reflector

53
Q

which mode provides the foundation for real-time, gray scale anatomic imaging?

54
Q

with a-mode, what is displayed on the y-axis?

A

amplitude of the reflected signal

55
Q

in m-mode, what is displayed on the x-axis?

56
Q

with b-mode, which axis is related to the strength of the reflection?

A

the z-axis is related to reflection strength

57
Q

a-mode

A

x-axis y-axis z-axis
depth amplitude none

58
Q

m-mode

A

x-axis y-axis z-axis
time depth none

59
Q

b-mode

A

x-axis y-axis z-axis
depth none amplitude

60
Q

ultrasound travels in a ______ line

61
Q

what is dynamic aperture

A

technique used to make the sound beam narrow over a greater range of depths which optimizes lateral resolution

62
Q

The focus created by a _____ diameter element is shallow

63
Q

the focus created by a _____ diameter element is

64
Q

apodization

A

the process of reducing the strength of the side and grating lobes

65
Q

In apodization, ____ signals excite the inner crystals and the _____ electrical signals excite the outer crystals.

A

stronger and weaker

This diminishes side lobes

66
Q

Mechanical Scanning

A

contain one disc shaped element (like a coin)

67
Q

array

A

a collection of active elements in a single transducer

68
Q

element

A

a single slab of pzt cut into separate pieces called elements

69
Q

channel

A

combination of electronic circuitry, the wire, and the element

70
Q

linear array

A

a group of ringed elements (target bulls eye) with a common center

71
Q

curvilinear array

A

elements arranged in an arc
2 types: curvilinear switched sequential array and curvilinear phased array

72
Q

with a mechanical transducer

A

the PZT crystal is physically moved to create an image

73
Q

Linear Array Transducers

A

active elements are arranged in a straight line

74
Q

Annular Array Transducers

A

elements are arranged as a circular rings with a common center

75
Q

Convex Array Transducers

A

active elements are arranged in a bowed or arched line. The transducer may be called curved or curvilinear

76
Q

Electrical Patterns

A

electronic slope creates a beam steering, and an electronic curvature creates beam transmit focusing

77
Q

slope

78
Q

curvature

A

transmit focusing

79
Q

3D is more accurately at ?

A

measuring volumes of structures such as cysts

80
Q

1 1/2 D arrays contain more elements side to side than up and down. This allows what?

A

focusing in the plane of the image, make thinner slices and improves elevational resolution

82
Q

disc shaped crystals make

A

thinnest slices and have the best elevational resolution within the focal zone

83
Q

the circle width in one direction is the ?

A

beam diameter (determines lateral resolution)

84
Q

the height of the circle

A

beam thickness (determines elevational resolution)

85
Q

at all depths the beam is much _____ than it is wide.

Physics C/O 2026 (12 decks)

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