chapter 6-8

Question 1

Logarithm / Log

Answer 1

represents > # : 10 that are multipled to create the original #

Question 2

positive decibel

Answer 2

signals > ⬆️ strength or getting larger

Question 3

when wave intensity doubles what is the relative change is

Answer 3

+3dB

Question 4

when wave intensity ten fold , what is the relative change is

Answer 4

+10dB

Question 5

negative decibel

Answer 5

signals > ⬆️ decrease or getting smaller

Question 6

when wave intensity is reduced to 1/2 , what is the relative change is

Answer 6

-3

Question 7

when wave intensity is reduced 1/10 , what is the relative change is

Answer 7

-10

Question 8

attenuation

Answer 8

sound wave weaken as they propagate > medium

Question 9

Attenuation determined by 2 factor

Answer 9

1.path length
2. frequency : sound

Question 10

distance / attenuation … related

Answer 10

directly

Question 11

father sound travels , _____ attenuation , ____ beam becomes

Answer 11

greater
weaker

Question 12

attenuation / frequency … related

Answer 12

directly

Question 13

Attenuation is ______ > _______ frequency sound

Answer 13

greater
higher

Question 14

3 processes contribute to attenuation

Answer 14

1. reflection
2. scattering
   3.absorption

Question 15

reflection

Answer 15

sound strikes the boundary, portion : wave energy may be redirected or reflected, back to sound sound

Question 16

Reflection occurs

Answer 16

when dimension : boundary > large

Question 17

2 forms : reflection

Answer 17

1. spectral
   2.diffuse

Question 18

specular reflection

Answer 18

boundary > smooth
sound > reflected in 1 directions in an organized manner

Question 19

specular reflection occurs

Answer 19

when light wave strikes a mirror

Question 20

1 limitation : specular reflection

Answer 20

once wave is slightly off-axis, reflection does not return to transducer

Question 21

diffuse reflection

Answer 21

wave reflects off an irregular surface it radiates in more than one direction

Question 22

another name for diffuse reflection

Answer 22

backscatter

Question 23

advantage : diffuse reflection

Answer 23

interface at suboptimal angles to the sound beam can still produce reflections that will return to the transducer

Question 24

disadvantage: diffuse reflection

Answer 24

signals has lower strength than specular reaction

Question 25

scattering

Answer 25

redirection : sound > many direction

Question 26

scattering occurs ..

Answer 26

tissue interface is small

Question 27

scattering / frequency .... related

Answer 27

directly

Question 28

ray scattering

Answer 28

structure : dimension > much smaller than beam wavelength

Question 29

ray scattering / frequency ..... related

Answer 29

directly

Question 30

absorption occurs

Answer 30

ultrasonic energy > converted into another energy form, ( heat)

Question 31

Absorption / frequency .... related

Answer 31

directly

Question 32

attenuation

Answer 32

process > sound energy is extracted from a wave by absorption, scattering, reflection

Question 33

total attenuation depends >

Answer 33

frequency : sound distance : beam travels tissue > sound wave travels

Question 34

Attenuation coefficient

Answer 34

: decibels : attenuation > occurs when sound travels 1 cm

Question 35

unit : attenuation coefficient

Answer 35

dB/cm

Question 36

attenuation coefficient / frequency .. related

Answer 36

directly

Question 37

1/2 value layer thickness >

Answer 37

distance sound travels > tissue > reduces intensity : sound to 1/2 it original value

Question 38

1/2 value layer describes

Answer 38

depth : tissue = 3dB : attenuation to intensity

Question 39

units : 1/2 value layer

Answer 39

cm units > length

Question 40

synonyms : 1/2 value layer

Answer 40

Penetration depth depth : penetration 1/2 boundary layer

Question 41

1/2 value layer thickness depends >

Answer 41

1. medium 2.frequency : sound

Question 44

reflection

Answer 44

produce as sound moves > 1 medium to another form basic u/s imaging

Question 45

transmission

Answer 45

u/s ability to image structure located deep > body

Question 46

acoustic impedance

Answer 46

tissue property > influence the amount : reflection

Question 47

Impedance

Answer 47

acoustic resistance > sound traveling > medium

Question 48

how is acoustic impedance calculated

Answer 48

multiplying density : medium by speed at which sound travels > medium

Question 49

how is impedance calculated

Answer 49

associated w/ medium > which sound travels

Question 50

reflection : u/S wave depends >

Answer 50

difference > acoustic impedance : 2 media at boundary

Question 51

units : impedance

Answer 51

rayls

Question 52

impedance > determined by

Answer 52

medium only

Question 53

synonyms > acoustic impedance

Answer 53

Characteristic impedance

Question 54

Incidence

Answer 54

angle at which angle strikes

Question 55

3 types of angles

Answer 55

1. acute 2. right 3.obtuse

Question 56

acute angle

Answer 56

less than 90

Question 57

right angles

Answer 57

exactly 90

Question 58

obtuse angles

Answer 58

greater than 90.

Question 59

Normal incidence

Answer 59

sound beam strikes boundary at exactly 90

Question 60

synonyms > normal incidence

Answer 60

perpendicular orthogonal right angle 90 degree

Question 61

Oblique incidence occurs

Answer 61

sound beam strikes boundary at any angle other than 90

Question 62

synonyms oblique

Answer 62

not at right angle non-perpendicular

Question 63

reflected intensity

Answer 63

sound beam, after striking boundary returns back from where it came

Question 63

incidence intensity

Answer 63

sound beam intensity immediately before it strikes boundary

Question 64

transmitted intensity

Answer 64

incident beam > after striking a boundary continues forward same general direction that it was traveling

Question 65

intensity reflection coefficient

Answer 65

% : Intensity > bounces back when sound beam strikes boundary b/w 2 media

Question 66

Intensity transmission. coefficient

Answer 66

% : Intensity > passes in forward direction when beam strikes an interface b/w 2 media

Question 67

how are IRC & ITC reported ?

Answer 67

%

Question 68

normal intensity

Answer 68

sound beam strike a tissue boundary at 90 angle

Question 69

reflection occurs only

Answer 69

if media on either side of boundary have different impedance

Question 70

transmission w. normal incidence

Answer 70

% : intensity > continues to move forward then beam reaches a boundary b/w 2 media

Question 71

w/ oblique incidence, reflection occurs

Answer 71

when impedance : 2 media are identical

Question 77

refraction

Answer 77

change > direction : wave propagation when traveling from 1 medium > another

Question 78

refraction associated w/ ... & occurs w/

Answer 78

transmission light wave / sound wave

Question 79

refraction occurs only if two conditions are satisfied...

Answer 79

1. oblique incidence ( not normal) 2. differ propagation speed : two media

Question 80

snells law

Answer 80

quantifies physics : refraction

Question 81

sine

Answer 81

unitless number w/ value from 0 - 1

Question 82

how do we identify medium 1 & 2

Answer 82

med 1 - sound currently traveling med 2 - sound entering

Question 83

under what conditions will transmission angle = incident angle

Answer 83

oblique incidence different propagation speed

Question 84

under what conditions will transmission angle greater than incident angle

Answer 84

when speed : med 2 is greater than speed : med 1

Question 85

under what conditions will transmission angle less than incident angle

Answer 85

when speed : med 2 less than speed : med 1

Question 86

go - return time / time : flight

Question 87

time : flight / how deep sound pulse travels .. related

Answer 87

directly

Question 88

13 microsecond rule

Answer 88

for every 13 us : go -return time object creating reflection = 1 cm deeper > body

Question 91

transducer

Question 92

ultrasound transducer perform 2 functions

Answer 92

transmission reception

Question 93

during transmission ....

Answer 93

electrical energy > system , converted > sound

Question 94

during reception ...

Answer 94

reflected sound pulse > converted > electricity

Question 95

piezoelectric effect

Answer 95

property : certain material to create voltage when mechanically deformed or pressure is applied to them

Question 96

piezoelectric material changes ... when ....

Answer 96

shape voltage is applied

Question 97

piezoelectric material coverts >

Answer 97

sound > electricity

Question 98

synonym PZT

Answer 98

ceramic active element crystal

Question 99

case

Answer 99

Cylindrical tube

Question 100

electoral shield

Answer 100

thin metallic barrier lignin inside : case

Question 101

acoustic insulator

Answer 101

thin barrier rubber prevents vibrations

Question 102

PZT / active elment

Answer 102

Crystal itself 1/2 wavelength thick

Question 103

wire

Answer 103

electrical connection b/w PZT / ultrasound system

Question 104

matching layer

Answer 104

front : PZT at face : transducer protects active element

Question 105

backing material

Answer 105

reduces ringing

Question 106

another name for backing material

Answer 106

damping material