US Physics Unit 3

studied byStudied by 3 people
5.0(3)
get a hint
hint

a pulse

1 / 94

encourage image

There's no tags or description

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

95 Terms

1

a pulse

short emission of sound (a few cycles)

New cards
2

pulses are separated in time with ____ of no emission (gaps/listening time)

periods

New cards
3

What is pulsed ultrasound based on

principle of echolocation

New cards
4

echolocation

this distance between structures and the ultrasound probe can be calculated by using this formula

New cards
5

2 way we look for

echo, round trip, time to reflector and back

New cards
6

1 way we look for

time for reflector

New cards
7

equation for 2 way

d=c(t/2)

New cards
8

equation for 1 way

d=ct

New cards
9

for imaging each pulse is ______ long for imaging

2-3 cycles

New cards
10

for doppler each pulse is ____ long

5-30

New cards
11

Determined by source of sound in PW

PRF, PRP, DF, PD, BW, QF

New cards
12

Determined by the source and the medium in PW

SPL

New cards
13

Pulse Repetition Frequency (PRF)

is the number of pulses per seconds (kHz)

New cards
14

The PRF for imaging

4-15 kHz

New cards
15

the PRF for Doppler

5-30 kHz

New cards
16

equation for PRF in kHz

# of pulses/s

New cards
17

Pulse Repetition Period (PRP)

is the time from the beginning of one pulse to the beginning of the next pulse (ms)

New cards
18

PRF is _____ related to PRP, just like frequency and period

inversely

New cards
19

A _____ PRF is desirable for image quality and Doppler sampling

high

New cards
20

PRF is ______ by the speed of sound in soft tissues

speed

New cards
21

Range ambiguity

when a pulse is sent out before all the echoes from the previous pulse have been received.

New cards
22

If PRF is increased, penetration or depth must

decrease

New cards
23

Pulse Duration (PD)

the time it takes for a single pulse to occur

New cards
24

equation for PD

T (# of cycles/pulse)

New cards
25

if frequency is increased, pulse duration is ______

decreased

New cards
26

for most diagnostic medical ultrasound, there are short periods when the machine is sending pulses into the body and _____ times when the machine is waiting for echoes

longer

New cards
27

Duty Factor (DF)

the percent of time that the sound is on (unitless)

New cards
28

For imaging the DF ranges from

0.1-0.1%

New cards
29

DF ranges from _____ in doppler

0.5-5%

New cards
30

DF equation

PD/PRP

New cards
31

Spatial Pulse Length (SPL)

the distance covered by a single pulse

New cards
32

SPL equation

wavelength (# of cycles/pulse)

New cards
33

Bandwidth (BW)

the range of frequencies contained in a pulse

New cards
34

Equation for BW

highest f- lowest f

New cards
35

CW Bandwidth

1

New cards
36

fractional bandwidth

is equal to the bandwidth divided by the operating frequency

New cards
37

equation for fractional bandwidth

BW/f0

New cards
38

Shorter pulses have ________ bandwidths

wider/broader

New cards
39

the _____ the pulse, the fewer number of cycles

shorter

New cards
40

having a broader bandwidth will result in ______ frequencies present

more

New cards
41

Quality Factor (QF)

refers to the purity of the beam or how close it is to the operating frequency

New cards
42

Equation for QF

f0/BW

New cards
43

we want _____ pulses so we can have a broad BW-improved resolution

short

New cards
44

PRF is the number of ____ occurring in 1 s

pulses

New cards
45

pulse-repetition ______ is the time from the beginning of one pulse to the beginning of the next

period

New cards
46

the PRP ______ while PRF increases

decreases

New cards
47

PD is the _____ it takes for a pulse to occur

time

New cards
48

SPL is the _____ of _____ that a pulse occupies while it travels

length, space

New cards
49

______ is the fraction of time that pulsed ultrasound is actually on

duty factor

New cards
50

PD equals the number of cycles in the pulse multiplied by

period

New cards
51

SPL equals the number of cycles in the pulse multiplied by _____

wavelength

New cards
52

the DF of continuous wave sound is

1

New cards
53

if the wavelength is 2 mm, the SPL for a 3 cycles pulse is _____mm

6

New cards
54

How many cycles are there in 1s of continuous wave 5MHZ ultrasound

5,000,000

New cards
55

Amplitude

difference between max value and equilibrium value of an acoustic variable

New cards
56

Power equation

P= Energy/ Time

New cards
57

Intensity equation

I=P/Area

New cards
58

The Intensity of a sound beam is _____ at its center than on the periphery

higher

New cards
59

the intensity of pulsed ultrasound also decreased toward the ____ of the pulse

end

New cards
60

Spatial Peak (SP)

is the greatest intensity in a pulse in reference to space

New cards
61

Spatial Average (SA)

is the average intensity across the pulse

New cards
62

PW is ____ uniform in space or time in terms of Intensity

not

New cards
63

The Beam Uniformity Ratio (BUR)

shows how uniform the intensity is in space

New cards
64

BUR equation

BUR= SP/SA

New cards
65

BUR will always be >1 because the peak will always be higher than the ____

average

New cards
66

Temporal Peak (TP)

is the greatest intensity measured as the pulse passes by

New cards
67

Pulse Average (PA)

is the average of all intensities measured as the pulse passes by

New cards
68

Temporal Average (TA)

includes all the time between the pulse being measured and the next pulse

New cards
69

SPTA

Spatial Peak/Temporal Average

Thermal interactions within tissue

New cards
70

FDA Limit on SPTA

<720 mW/cm2

New cards
71

Attenuation

the weakening of sound as it propagates

New cards
72

gain

an increase in strength of the sound wave

New cards
73

dynamic range

the ration of largest to smallest power in dB

New cards
74

Intensity Ratio

I/Io

New cards
75

I/I0 < 1

I<Io

New cards
76

I/Io>1

I>Io

New cards
77

I/Io=1

I=Io

New cards
78

Equation for dB

10 log (I/Io)

New cards
79

If I/Io <

=-dBi

New cards
80

If I/Io>1

+dB

New cards
81

If I/Io=1

=0 dB

New cards
82

How do we get gain?

Constructive interference, and amplifiers

New cards
83

Time Gain Compensation (TGC)

How to change this to make the picture stronger

New cards
84

-3dB represents a reduction in intensity or power by a factor of

2

New cards
85

-10dB represents a reduction in intensity or power by

10

New cards
86

-6dB represents a reduction in amplitude by a factor of

2

New cards
87

Amplitude is the maximum _____ that occurs in an acoustic variable

variation

New cards
88

Intensity is the ___ in a wave divided by _____

power, area

New cards
89

A unit for intensity is ______

mW/cm2

New cards
90

Intensity is proportional to ______ squared

amplitude

New cards
91

if power is doubled and area remains unchanged, intensity is ________

doubled

New cards
92

if area is doubled and power remains unchanged, intensity is ______

halved

New cards
93

if both power and area are doubled, intensity is ______

unchanged

New cards
94

if amplitude is doubled, intensity is _______

quadrupled

New cards
95

Attenuation is the reduction in ___ and ___ as a wave travels through a medium

amplitude, intensity

New cards

Explore top notes

note Note
studied byStudied by 10 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 20564 people
Updated ... ago
4.5 Stars(99)
note Note
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 3 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 40 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 8 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 5572 people
Updated ... ago
4.3 Stars(23)

Explore top flashcards

flashcards Flashcard36 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard82 terms
studied byStudied by 49 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard60 terms
studied byStudied by 4 people
Updated ... ago
4.0 Stars(1)
flashcards Flashcard154 terms
studied byStudied by 10 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard42 terms
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard159 terms
studied byStudied by 12 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard34 terms
studied byStudied by 11 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard70 terms
studied byStudied by 84 people
Updated ... ago
5.0 Stars(2)