DISCLOSURE Frederick W. Kremkau, Ph.D.
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1 DISCLOSURE Frederick W. Kremkau, Ph.D. Elsevier: Textbook Royalties ULTRASOUND: Sound We Don’t Hear Frederick W. Kremkau, Ph.D. “SONOGRAPHY” etymology is Sono sonos: [Latin] “sound” graphy < Image: a representation ________________ _______________ PULSE ECHOES SCAN LINE DATA LINE; ECHO LINE
Transcript of DISCLOSURE Frederick W. Kremkau, Ph.D.
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DISCLOSURE
Frederick W. Kremkau, Ph.D.
Elsevier: Textbook Royalties
GE Healthcare: Consultant
Philips Healthcare: Consultant
Sonosim: Consultant
ULTRASOUND: Sound We Don’t Hear
Frederick W. Kremkau, Ph.D.
“SONOGRAPHY” etymology isSono sonos: [Latin] “sound”
graphy ΥραΦειν: [Greek] “to write”
< Image: a representation
_______________________________
PULSE
ECHOES
SCAN LINEDATA LINE; ECHO LINE
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1 scan line1 scan line 5 scan lines
48 scan lines 96 scan lines
192 scan lines
sector
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1. Ultrasound
2. Transducers
3. Instruments
1. Ultrasound
2. Transducers
3. Instruments
1. Ultrasound• Sound• Pulsed Ultrasound• Attenuation• Echoes
Courtesy Steve Knight, BSc, RVT, RDCS
pressure
distance
cycle
wavelength
amplitude
amplitude
wavelength
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periodcycle
pressure
time
amplitude
frequency = cycles in one sec
1 second
5 cycles per secondFREQUENCY
Number of per second.
cycle per second
HeinrichHertz 1890
Can you hear 5 Hz?
INFRASOUND
< 20 Hz
No!
[below]
5
1 microsecond
5 million hertz
μεγας = large
No!
beyond
Can you hear 5 MHz?
millionbeyondThis form of sound (MHz) is called __________.ultrasound
Tones
large
ULTRASOUND
> 20 kHz
My favorite frequency is 40,000 Hz.What’s yours?
30 kHz ispopular now.Have you heard it?
Tones
frequency
period
1 s
4 MHz
10 MHz
740 mph
U.S. Navy FA-18 Hornet
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SPEED
LIMIT
1.54mm/µs
= c_f
frequency
wavelength 1 ms
PRF = 3 kHz
Pressure
Time
pulserepetition
period
(0.2 ms)
pulseduration
(0.04 ms)
Time
PRP (100 %)
(95 %)
(5 %)
DUTY FACTORFraction of time pulsed sound is on.
3 cycles
amplitude
travel
length higherfrequency
wavelengthfrequency
SPL
pc
pr
distance
pressure
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INTENSITY
power divided by area
[W/cm2]
“A lens like the one found at Jamestowncould have been used in telescopes but also to fire tinder with a char cloth in the tinderbox.”
Colonial Williamsburg JournalWinter 2006
A t t e n u a t i o n
ATTENUATION
Reduction in amplitude and intensity with travel.
[decibels per centimeter (dB/cm)]
attenuation =
absorption + scattering
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3 dB 1/2
10 dB 1/10
frequency
attenuation
penetration
3 MHz17 cm
5 MHz11 cm
7 MHz7 cm
Demo2.00
20 MHz
frequencyperiod
wavelengthSPL
attenuationpenetration
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0.5 dB/cm-MHz
(0.5 dB/cm-MHz) x cm x MHz = dB
0.5 dB/cm-MHz x 4 cm x 3 MHz = 6 dB
0.5 dB/cm-MHz x 5 cm x 4 MHz = 10 dB
= density x propagation speedimpedance
diffe
renc
e
=ir
tsame speedfaster speedslower speed
percent speed change ~ percent angle change
SPECULARLatin: mirror-like
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50 mph4 hours200 miles round trip100 miles one way
How far?
d = ½ c t= ½ x 1.54 x 13= 10 mm = 1 cm
RangeEquation SUN TUEMON WED THU SAT
AUG 2021
1 2 3 4 5 6 7
8 9 10 11 12 14
13 µs/cmround-trip travel time
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FRI
T
1 cm
[2 cm of travel]
13 μs 1 cm
65 μs 5 cm
130 μs 10 cm
• Pulse-Echo Principle• Sound • Pulsed Ultrasound• Attenuation• Echoes
TRAN
