Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

US - Understanding US Physics > US - Understanding US Physics - 6 > Flashcards

US - Understanding US Physics - 6 Flashcards

1
Q

STR of attenuation r/t STR of amplitude

A

inverse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

importance of increasing 1-log

A

by increasing 1-log&raquo_space; 10x more

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

DECIBEL NOTATION - absolute? measured? calculated?

A

.relative measurement

. comparison

.ratio

.logarithmic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

DECIBELS require…

A

2 intensities… start & final

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

positive DECIBELS

A

final intensities is LARGER than start intensities

INCREASES in intensities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

negative DECIBELS

A

final intensities is SMALLER than start intensities

DECREASES in intensities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

+ 3dB

A

final intensity is DOUBLE start intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

+ 10dB

A

final intensity is 10x TIMES start intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  • 3dB
A

final intensity is HALF (1/2) start intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  • 10dB
A

final intensity is ONE-TENTH (1/10) start intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

ex: meaning of 6dB change?

A

** +3dB = 2x

6dB = 2 x (+3dB)
6dB = 2 x (2x)
6dB = 4x

final intensity is [[4x]] start intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

ex: sound increases by a factor of 100?

want: decibel notation?

A

** 10x = +10dB

100 = 10 x 10
100 = 2 x (+10dB)
100 = [[[+20dB]]]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

def ATTENUATION

A

= as sound propagates thru medium, sound pulse STR(Power, Amplitude, Intensity) decreases,

.SAME speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

ATTENUATION - 2 factors

A

. distance
. frequency of sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ATTENUATION r/t its 2 factors

A

direct

up ATTENUATION
up DISTANCE
up FREQUENCY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

ATTENUATION r/t decibels

A

ATTENUATION = negative decibels due to decreases in sound pulse STR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

ATTENUATION - 3 processes

A

SAR-Attenuation

.scatter
.absorption
.reflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

def REFLECTION

A

= when sound waves strike a LARGE BOUNDARY, redirected back to the sound source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

REFLECTION - 2 types

A

specular REFLECTION

diffuse REFLECTION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

def SPECULAR REFLECTION

A

= 1 direction reflected
. smooth boundary

BAD - at off-axis or off angle = no reflection

GOOD - stronger STR reflection than diffuse reflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

def DIFFUSE REFLECTION

A

aka BACKSCATTER
=multi direction
=irregular surfaces

GOOD - suboptimal angle

BAD - weaker STR reflection than specular reflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

def SCATTERING

A

= SMALL boundary, sound waves RANDOMLY directed, in MULTI-direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

SCATTERING r/t frequency

A

direct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

example of SCATTERING

A

lung tissues due to alveoli are filled with AIR

*AIR has HI-attenuation = HI-frequency&raquo_space; HI-scattering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
def RAYLEIGH SCATTERING
= organized =omnidirectional scattering (in all direction)
26
RAYLEIGH SCATTERING - example
red blood cells
27
RAYLEIGH SCATTERING equation r/t frequency
RAYLEIGH SCATTERING = frequency (^4) 4th power
28
REFLECTION - organized, back to transducer
specular REFLECTION
29
REFLECTION - organized, in all direction
rayleigh REFLECTION
30
REFLECTION - disorganized, back to transducer
diffuse / backscatter REFLECTION
31
REFLECTION - disorganized, in all directions
scattering REFLECTION
32
importance in US r/t attenuation, reflection & scattering
UP f DOWN pulse UP accuracy UP attenuation DOWN depth therefore, to UP.accuracy & UP.depth >> US goal, to UP.f as much as possible for HI.accuracy without compromising DEPTH
33
def ABSORPTION
= when US energy is converted into another energy form (heat)
34
ABSORPTION r/t frequency
direct
35
ABSORPTION r/t DEPTH, f, attenuation, pulse.L
up ABSORPTION up frequency >> up attenuation down pulse.L DOWN depth
36
ABSORPTION r/t UP.depth....f, attenuation, pulse.L
down ABSORPTION down frequency >> down attenuation up pulse.L UP depth
37
def ATTENUATION COEFFICIENT
= number of decibels of attenuation when sound travels 1cm = dB/cm *regardless of sound travel distance
38
ATTENUATION COEFFICIENT r/t sound travel distance
UNrelated
39
TOTAL ATTENUATION depends on (3)...
.sound frequency .beam travel distance .tissue type
40
TOTAL ATTENUATION equation
TOTAL ATTENUATION (dB) = ATTENUATION COEFFICIENT (dB/cm) x distance (cm)
41
ATTENUATION COEFFICIENT - soft tissue value
0.5 dB/cm/MHz
42
ATTENUATION COEFFICIENT equation
ATTENUATION COEFFICIENT (dB/cm) = f (MHz) / 2
43
ATTENUATION COEFFICIENT r/t frequency
direct
44
arrange ATTENUATION MEDIUM from hi>>low
hi>>low AIR BONE & LUNG MUSCLE SOFT TISSUE FAT FLUIDS, BLOOD, URINE WATER
45
ATTENUATION r/t AIR & its f
air ATTENUATION 100% f > 1MHz
46
ATTENUATION r/t LUNG, type reflection
LUNG ATTENUATION more than SOFT TISSUES hi SCATTERING reflection due to air in lung tissue
47
ATTENUATION r/t WATER, its f
water ATTENUATION less than SOFT TISSUES hi HI f ~10MHz
48
ATTENUATION r/t muscles
depends if sound travels along or across fibers
49
def HALF-VALUE LAYER THICKNESS
aka PENETRATION DEPTH aka HALF BOUNDARY LAYER =distance sound travels in tissue that reduces half original intensity of sound
50
HALF-VALUE LAYER THICKNESS - US range
0.25 - 1cm
51
HALF-VALUE LAYER THICKNESS depends on (2)
medium sound frequency
52
thin HALF-VALUE LAYER THICKNESS & its medium (3)
HI f HI attenuation lung, bone, air
53
thick HALF-VALUE LAYER THICKNESS & its medium (3)
LOW f LOW attenuation fat, fluid, water
54
def IMPEDANCE
= acoustic impedance = characteristic impedance **CALCULATED!!!!!, not measured
55
IMPEDANCE equation
IMPEDANCE (rayls, Z) = DENSITY (kg/m^3) x propagation speed (m/s)
56
IMPEDANCE - range
1.25 - 1.75 Mrayls
57
IMPEDANCE - determined by
medium
58
def INCIDENCE
the angle at which the waves strike the boundary determines the behavior of the pulse
59
oblique angle
any angles NOT 90 degrees
60
acute angle
LESS than 90 degrees
61
right angle
90 degrees
62
obtuse angle
MORE than 90 degrees
63
def normal incidence
= the incident sound beam strikes the boundary at exactly 90 degrees aka PORN .Perpendicular .Orthogonal .Right angle .Ninety degrees
64
def oblique incidence
= when the incident sound beam strikes the boundary at angle NOT 90 degrees
65
what occurs at the boundary between 2 media?
CONSERVATION OF ENERGY, 100%
66
INCIDENT intensity equation
INCIDENT intensity (W/cm^2) = REFLECTED intensity + TRANSMITTED intensity
67
def INTENSITY REFLECTION COEFFICIENT (IRC)
IRC = percentage of reflected intensity
68
IRC value for soft tissue
equal, less than 1%
69
IRC r/t soft-hard tissues
up IRC b/t SOFT-HARD tissues
70
def INTENSITY TRANSMISSION COEFFICIENT (ITC)
= percentage of transmission intensity
71
ITC value for soft tissues
equal, more than 99%
72
ITC r/t soft-hard tissues
down ITC b/t SOFT-HARD tissues
73
IRC & ITC equation r/t energy conservation
100% = IRC + ITC
74
units INTENSITIES vs COEFFICIENT
intensity (W/cm^2) coefficient (%)
75
def REFLECTION w/ NORMAL incident
= when incident strikes at 90* b/t media with DIFF IMPEDANCE
76
what happens to REFLECTION w/ NORMAL incident with SAME IMPEDANCE?
SAME impedance no REFLECTION w/ NORMAL incident
77
REFLECTION w/ NORMAL incident r/t DIFF in IMPEDANCE
direct
78
INTENSITY REFLECTION COEFFICIENT equation
IRC (%) = [Z2 - Z1 / Z2 +Z1]^2 x {100}
79
def INTENSITY TRANSMISSION COEFFICIENT (ITC)
= percentage intensity that continues to move forward at boundary b/t 3 media
80
100% ITC
b/t 2 media with SAME IMPEDANCE
81
INTENSITY TRANSMISSION COEFFICIENT (ITC) equation
INTENSITY TRANSMISSION COEFFICIENT (ITC) {%} = transmitted intensity (W/cm^2) / incident intensity (W/cm^2) X {100}
82
INTENSITY TRANSMISSION COEFFICIENT (ITC) equation r/t energy conservation
ITC (%) = 1 - IRC (%) 100% = ITC + IRC
83
def REFLECTION & TRANSMISSION w/ OBLIQUE INCIDENCE
its not YOU, it's ME kinda COMPLICATION
84
REFLECTION & TRANSMISSION w/ OBLIQUE INCIDENCE - 2 physical principles
. conservation of energy . reflection angle = incident angle
85
explain CONSERVATION OF ENERGY r/t OBLIQUE INCIDENCE -
100% = reflected coefficient + transmission coefficient incident intensity (W/cm^2) = reflecte intensity + transmitted intensity
86
explain REFLECTION ANGLE = INCIDENT ANGLE r/t OBLIQUE INCIDENCE draw **note CH6
.in oblique incidence, the sound beam does not reflected directly back to the transducer .with the IMAGINARY LINE locates PERPENDICULAR to the boundary, the INCIDENT angle = REFLECTED angle
87
example of REFLECTION ANGLE = INCIDENT ANGLE r/t OBLIQUE INCIDENCE
car rear view mirror
88
def REFRACTION draw *note CH6
= transmission with a bend = change in direction of wave propagation after it crosses the boundary
89
REFRACTION - needs 2 conditions
. oblique incidence . diff propagation speed b/t 2 media
90
low REFRACTION r/t speed, b/t media
low REFRACTION ~similar speed soft-fat muscle-blood soft-fluid
91
hi REFRACTION r/t speed, b/t media
hi REFRACTION DIFF speed bone-soft
92
SNELL's LAW
=physics attempt to explain refraction
93
SNELL's LAW equation
sin{transmission angle} / sin{incident angle} = [propagation speed 2] / [propagation speed 1]
94
def SINE draw *note CH6
= angle adjacent to the side
95
draw NO REFRACTION r/t angle and speed
NO refraction same angle degree same speed
96
draw YES REFRACTION r/t angle and speed (large vs small)
YES refraction with LARGE diff .incident < transmission angle .speed 1 < speed 2 YES refraction. with SMALL diff .incident > transmission angle .speed 1 > speed 2

US - Understanding US Physics (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions