Non-linear acoustics in Ultrasound Imaging Hans Torp Department of Physiology and Biomedical...
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Transcript of Non-linear acoustics in Ultrasound Imaging Hans Torp Department of Physiology and Biomedical...
Non-linear acoustics in Ultrasound ImagingNon-linear acoustics in Ultrasound Imaging
Hans TorpHans Torp
Department of Physiology and Biomedical EngineeringDepartment of Physiology and Biomedical Engineering
NTNUNTNU
NorwayNorway
Hans TorpNTNU, Norway
Non-linear acoustics in Non-linear acoustics in Ultrasound ImagingUltrasound Imaging
Body wall
object
Nonlinear propagation
Transducer
nonlinear scattering
Hans TorpNTNU, Norway
Nonlinear propagationNonlinear propagation
0.5 1 1.5 2 2.5 3 3.5
x 10-6
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
Transmitted pulse
0.5 1 1.5 2 2.5 3 3.5
x 10-6
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
0.12
Pulse after 6cm propagation
0 1 2 3 4 5 6 7 8 9 10
x 106
-40
-30
-20
-10
0
10
20
0 1 2 3 4 5 6 7 8 9 10
x 106
-40
-30
-20
-10
0
10
20
frequencyfo 2fo 3fo frequencyfo 2fo 3fo
Received signal is filtered byReceived signal is filtered by1. transducer1. transducer2. Frequency dependent attenuation2. Frequency dependent attenuation
0 2 4 6 8 10x 106
-70
-60
-50
-40
-30
-20
-10
0
Hans TorpNTNU, Norway
Measured RF- spectrumMeasured RF- spectrumFrequency range 1- 4 MHzFrequency range 1- 4 MHz
0 1 2 3 4 5x 106
-20
0
20
40
60
80
Signal from ventricular septumNoise from LV cavity
Hans TorpNTNU, Norway
Fundamental and second harmonic Fundamental and second harmonic signal separated by filtersignal separated by filter
0 1 2 3 4 5x 106
-20
0
20
40
60
80
450
Fundamental 2. harmonicSignal from septumNoise from LV cavity
-500 0 5000
50
100
150
200
250
-10 0 100
50
100
150
200
250
Hans TorpNTNU, Norway
Water tank experimentWater tank experiment
0 2 4 6x 106
-20
0
20
40
60
80
100
Full band 2nd Harmonic
Hans TorpNTNU, Norway
Second harmonic imagingSecond harmonic imagingReverberation noise is suppressedReverberation noise is suppressed
Conventional Bmode imagingftx=3.4 MHz, frx=3.4 MHz
2.harmonic Bmode imagingftx=1.7 MHz, frx=3.4 MHz
0 1 2 3 4 5x 106
-20
0
20
40
60
80
FrequencySignal
Noise
Hans TorpNTNU, Norway
Cardiac examples 3.5 MHz probeCardiac examples 3.5 MHz probe
Fundamental Octave
Hans TorpNTNU, Norway
Brain - 18 week fetus 5 MHz probeBrain - 18 week fetus 5 MHz probe
Fundamental OctaveHans TorpNTNU, Norway
Brain - 18 week fetus 5 MHz probeBrain - 18 week fetus 5 MHz probe
Fundamental Octave
Hans TorpNTNU, Norway