# FINAL

Studied by 45 people
5.0(1)
get a hint
hint

What is the principle of Piezoelectricity?

1 / 349

### There's no tags or description

Looks like no one added any tags here yet for you.

### 350 Terms

1

What is the principle of Piezoelectricity?

“Some materials, when deformed by an applied pressure, produce a voltage”

New cards
2

What happens when a voltage is applied to a Piezoelectric element? What does this depend on?

1. Thickness of element increases or decreases

2. Depends on polarity of voltage

New cards
3

What would happen if a synthetic Piezoelectric element was created and reheated to the Curie point?

Destroys all Piezoelectric properties

New cards
4

What is the fo (operating freq) of a crystal determined by?

1. Crystal

1. Propogation speed

2. Thickness

New cards
5

Operating Frequency (fo) Formula

fo = cPZT / 2 * cth

New cards
6

How are thickness and operating frequency related?

1. Indirectly

1. Thin elements = high freq

2. Thick elements = low freq

New cards
7

What is the sound beam a combination of?

All sound arising from different point-like sources (wavelets) on transducer crystal face

New cards
8

What occurs due to the superposition of all sound waves in the beam?

Natural focusing (narrowing)

New cards
9

How is the shape of the sound beam determined?

Crystals

New cards
10

Axial Plane

1. Along direction of sound travel

2. Parallel

New cards
11

Lateral Plane

Perpendicular to direction of sound travel

New cards
12

Elevational Plane

Thickness of sound beam

New cards
13

What produces the width of a sound beam? How is the width determined?

1. Transducer

2. The distance from the transducers face

New cards
14

Is intensity uniform throughout a beam? Why?

1. No

2. Area varies (intensity = power/area)

New cards
15

How are beam diameter and resolution related?

1. Inversely

1. Small beam = good resolution

2. Large beam = bad resolution

New cards
16

Near Zone

1. AKA Fresnel zone, near field

2. Region extending from transducer to minimum beam width

New cards
17

Focal Point

1. Smallest beam

2. Maximum intensity

New cards
18

When does a beam have the best resolution?

At the focal point

New cards
19

Focal Zone

1. Where beam is focused on each side of focal point

2. Maximum

1. Sensitivity

2. Intensity

New cards
20

When does a beam have the best lateral resolution?

At the focal zone

New cards
21

How are diameter and intensity related in the focal zone?

1. Inversely

1. Diameter decreases = intensity increases

2. Diameter increases = intensity decreases

New cards
22

Near Zone Length (NZL)

1. Distance from transducer face to where the beam has the smallest diameter

New cards
23

How are diameter and NZL related?

1. Directly

1. Increase diameter = increase NZL

2. Decrease diameter = decrease NZL

New cards
24

How are frequency and NZL related?

1. Directly

1. Increase diameter = increase NZL

2. Decrease diameter = decrease NZL

New cards
25

Far Field Divergence (FFD)

When the beam diameter increases after natural focus

New cards
26

How are diameter and far field divergence related?

1. Indirectly

1. Increased diameter = Low divergence

2. Decreased diameter = High divergence

New cards
27

How are frequency and far field divergence related?

1. Indirectly

1. Increased frequency = Low divergence

2. Decreased frequency = High divergence

New cards
28

At a distance of one near zone length the diameter of the beam is…?

½ the crystal diameter

New cards
29

At a distance of 2 near zone lengths the diameter of the beam is…?

The crystal diameter

New cards
30

What two things does focusing contribute to?

1. Better resolution (narrow beam)

2. Stronger beam (decreased area)

New cards
31

A-mode (Amplitude Mode)

1. Displayed on graph

1. X-axis = depth

2. Y-axis = strength

New cards
32

B-mode (Brightness Mode)

1. 2D images, B-scans, displayed on a matrix

2. Displayed dots with brightness

New cards
33

What does brightness on B-mode show?

1. Strength

2. Location

New cards
34

M-mode (Motion Mode)

1. Displayed on a graph

1. X-axis = time

2. Y-axis = depth

New cards
35

What imaging mode is used most used today?

B-mode

New cards
36

What imaging mode is used for cardiac and fetal cardiac?

M-mode

New cards
37

Transducer (Probe)

Device that converts one form of energy to another

New cards
38

Bandwidth (BW)

Range of frequencies produced by the transducer

New cards
39

How are pulse length and bandwidth diameter related?

1. Inversely

1. Short pulses = broad bandwidth

2. Long pulses = narrow bandwidth

New cards
40

Damping (Backing) Material

Epoxy resin attached to back of element

New cards
41

What does damping material do?

1. Absorbs vibrations

2. Reduces #cycles/pulse

New cards
42

How are pulse duration (PD) and spatial pulse length (SPL) related to resolution?

1. Low PD and SPL = Improved resolution

2. High PD and SPL = Reduced resolution

New cards
43

How is bandwidth with damping related to quality factor, efficiency, and sensitivity?

1. Inversely

1. Increased bandwidth and damping = Decreased QF, efficiency and sensitivity

2. Decreased bandwidth and damping = Increased QF, efficiency and sensitivity

New cards
44

How are diagnostic imaging transducers damped? How many cycles per pulse does this produce?

1. Highly damped

2. 2-3 cycles per pulse

New cards
45

How are pulsed-wave Doppler transducers damped? How many cycles per pulse does this produce?

1. Less damped

2. 5-30 cycles per pulse

New cards
46

How are continuous wave Doppler transducers damped? Why?

1. Not damped

2. Reflects all energy into patient

New cards
47

What does quality factor determine?

Sensitivity

New cards
48

What does quality factor detect?

Weak echoes

New cards
49

Quality Factor (QF) Formula

fo / BW

New cards
50

Matching Layer

1. Located on the transducer face

2. Has impedance value between crystal and tissue

New cards
51

What does the matching layer do?

Reduces reflection

New cards
52

How are frequency and penetration related?

1. Low frequency = Improved penetration

2. High frequency = Reduced penetration

New cards
53

How are penetration and resolution related?

1. Improved penetration = Reduced resolution

2. Reduced penetration = Improved resolution

New cards
54

What is a complete scan of the ultrasound beam called?

Frame

New cards
55

What is required for real-time scanning?

Transducer arrays

New cards
56

What means are used for sweeping, steering, and focusing the beam? What is this accomplished by?

1. Electronic means involving constructive interference

2. Accomplished by

1. Sequencing

2. Phasing

New cards
57

What is the time delay between pulses determined by?

Depth (time it takes for all echoes to return)

New cards
58

Beam Steering

1. Sweeping the beam

2. Accomplished with phasing

New cards
59

What does beam steering produce?

Automatic scanning

New cards
60

How are time and beam steering related?

1. Directly

1. Increased delay = Increased steering

2. Decreased delay = Decreased steering

New cards
61

How do you know what direction a beam is going during beam steering?

1. Beam goes toward side activated last

2. Right to left = steered left

3. Left to right = steered right

New cards
62

How are time and focus related during electronic (transmit) focusing?

1. Inversely

1. Increased delay of curvature = Closer focus

2. Decreased delay of curvature = Deeper focus

New cards
63

Linear Array

1. Straight line of elements

2. Rectangular image

3. Vertical, parallel scan lines

New cards
64

What can be done during linear array to produce a parallelogram?

Can be steered to right or left (in Doppler)

New cards
65

Curved (Convex) Array

1. Curved line of elements

2. Produces sector image

3. Pulses travel in different directions from different origins

New cards
66

Phased (Sector) Array

1. Compact line of elements

2. Produced pie shaped image

3. Pulses travel in different directions from same origin

New cards
67

What occurs during phased array?

Voltage pulses applied to entire group of elements with varying time delays = sweeping of beam

New cards
68

Vector Array

Parallelogram-shaped display

New cards
69

What is a 2D array? What can they do?

1. Matrix of elements

2. Ability to steer and focus in two dimensions

3. Allows for focusing in elevational plane by phasing

New cards
70

Name the three spatial categories of resolution

1. Axial

2. Lateral

3. Elevational

New cards
71

What does spatial resolution give us the ability to see?

Detail on an image

New cards
72

What is spatial resolution related to?

1. Directly related to # of scan lines

2. Related to # of pixels in a monitor

New cards
73

What size resolution is always better?

1. Smaller

2. Less distance between reflectors to be displayed as separate objects

New cards
74

What is axial resolution?

The minimum reflector separation necessary to resolve reflectors parallel to sound beam

New cards
75

What is axial resolution determined by?

SPL

New cards
76

What does LARD stand for? (Has to do with AR)

Longitudinal, Axial, Range, Depth

New cards
77

To improve AR, SPL must be _____

Reduced

New cards
78

As SPL decreases, AR ____

Decreases

New cards
79

As frequency increases, AR _____

Decreases

New cards
80

Does axial resolution change with depth? Why?

1. No

2. AR is constant along beam path

New cards
81

What is lateral resolution?

Minimum reflector separation necessary to resolve reflectors perpendicular to beam

New cards
82

What is lateral resolution determined by?

Beam width

New cards
83

Does lateral resolution vary with depth? Why?

1. Yes

2. Because of sound beam shape

New cards
84

What does LATA stand for? (Has to do with LR)

Lateral, Angular, Transverse, Azimuthal

New cards
85

Elevation resolution varies with ____ because of the shape of the sound beam

Depth

New cards
86

What is contrast resolution?

The ability of gray-scale display to distinguish subtle differences in echogenicity, or brightness, of adjacent tissues

New cards
87

What is contrast resolution determined by?

1. Number of pixels in an image

2. Number of shades of gray displayed in each pixel

New cards
88

What is contrast resolution controlled by?

1. System’s memory

2. Dynamic range settings

New cards
89

What is temporal resolution?

Ability to follow moving structures in temporal detail

New cards
90

What is frame rate?

Number of images displayed per second

New cards
91

Faster FR = _____ temporal resolution

Improved

New cards
92

Frame Rate is dependent on… (5 things)

1. Line density

2. Lines per frame

3. Depth & PRF

4. Sector Width

5. Number of foci

New cards
93

What is line density?

1. # of scan lines per degree of sector

2. # of scan lines per centimeter

New cards
94

What is lines per frame?

# of lines in each frame

New cards
95

More lines = ____ spatial resolution

Improved

New cards
96

How are line density and lines per frame related to FR?

Inversely

New cards
97

____ sector width improves image quaility

Low

New cards
98

Why does a low sector width improve image quaility?

1. Less tissue interrogated

2. Less artifacts

3. Improved signal to noise ratio

4. Improves contrast resolution

New cards
99

Depth and PRF are ____ related

Inversely

New cards
100

Depth is ____ related to FR

Inversely

New cards

## Explore top notes

Note
Studied by 5 people
Updated ... ago
5.0 Stars(1)
Note
Studied by 10 people
Updated ... ago
5.0 Stars(2)
Note
Studied by 11 people
Updated ... ago
5.0 Stars(1)
Note
Studied by 40 people
Updated ... ago
5.0 Stars(1)
Note
Studied by 4 people
Updated ... ago
5.0 Stars(1)
Note
Studied by 11 people
Updated ... ago
5.0 Stars(1)
Note
Studied by 4 people
Updated ... ago
5.0 Stars(1)
Note
Studied by 126 people
Updated ... ago
4.0 Stars(1)

## Explore top flashcards

Flashcard75 terms
Studied by 15 people
Updated ... ago
5.0 Stars(1)
Flashcard21 terms
Studied by 45 people
Updated ... ago
4.8 Stars(5)
Flashcard44 terms
Studied by 22 people
Updated ... ago
5.0 Stars(1)
Flashcard355 terms
Studied by 7 people
Updated ... ago
5.0 Stars(1)
Flashcard28 terms
Studied by 6 people
Updated ... ago
5.0 Stars(1)
Flashcard20 terms
Studied by 7 people
Updated ... ago
5.0 Stars(1)
Flashcard27 terms
Studied by 4 people
Updated ... ago
5.0 Stars(1)
Flashcard40 terms
Studied by 4351 people
Updated ... ago
4.1 Stars(36)