Introduction to the Physics Echocardiography Introduction to the Physics Echocardiography Jose L....
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Transcript of Introduction to the Physics Echocardiography Introduction to the Physics Echocardiography Jose L....
Introduction to the Introduction to the Physics Physics
Echocardiography Echocardiography
Jose L. Rivera, M.D.Jose L. Rivera, M.D.January 9, 2010January 9, 2010
The Basic PhysicsThe Basic Physics
• Image Generation: The Physics of Image Generation: The Physics of Ultrasound Doppler Imaging Modalities & Ultrasound Doppler Imaging Modalities & Measurement of Blood VelocitiesMeasurement of Blood Velocities
• Use of Calculus to manipulate ultrasound Use of Calculus to manipulate ultrasound Doppler informationDoppler information
ObjectivesObjectives
• Explain how the various modes of Explain how the various modes of ultrasound image are generatedultrasound image are generated
• Define the basic physics and calculus Define the basic physics and calculus concepts used in medical ultrasound concepts used in medical ultrasound imagingimaging
ObjectivesObjectives
• Discuss the utility and applications of Discuss the utility and applications of Doppler color flows imaging.Doppler color flows imaging.
• Explain the difference between Pulsed Explain the difference between Pulsed Doppler and Continuous Doppler and their Doppler and Continuous Doppler and their applicationsapplications
Physics of EchocardiographyPhysics of Echocardiography
Brief Review of Echocardiography Physics to:
Understand the generation, propagation and detection of Ultrasounds Waves
Explain how the physical principles affect our measurements and images
Appreciate the strengths and limitations of the technology
THE BASIC PHYSICSTHE BASIC PHYSICS
• ULTRASOUND WAVES IN A FLUID BEHAVE ULTRASOUND WAVES IN A FLUID BEHAVE LIKE ELECTROMAGNETIC WAVES IN A LIKE ELECTROMAGNETIC WAVES IN A VACUUMVACUUM
• THEIR ENERGY SOURCE ORIGINATES FROM THEIR ENERGY SOURCE ORIGINATES FROM ELECTROMAGNETIC WAVES & THEY RETAIN ELECTROMAGNETIC WAVES & THEY RETAIN SOME OF THOSE WAVE PROPERTIESSOME OF THOSE WAVE PROPERTIES
• THEIR PROPERTIES CAN BE ANALYZED WITH THEIR PROPERTIES CAN BE ANALYZED WITH BASIC CALCULUS (Integral & Differential)BASIC CALCULUS (Integral & Differential)
• The following diagrams on the following slides were obtained from Sidebotham’s The following diagrams on the following slides were obtained from Sidebotham’s “Perioperative Transesophageal Echocardiography“Perioperative Transesophageal Echocardiography
Piezoelectric EffectPiezoelectric Effect
Piezoelectric effect results inCompression & Rarefaction: The Shockwave
Damping Material is used to “ring down” the Pulse Length & Bandwidth which results in
improved resolution
Ultrasound Interactions with Tissue
Interfaces
Arrow represent Vectors whose length equal the Arrow represent Vectors whose length equal the strength & direction of the reflected signalstrength & direction of the reflected signal
A and B represent specular (mirror like) reflectors, A and B represent specular (mirror like) reflectors, the B return signal does not return to the transducerthe B return signal does not return to the transducer
C and D have a rough surface that is typical of human C and D have a rough surface that is typical of human tissuetissue
E are objects smaller than a wavelength & therefore E are objects smaller than a wavelength & therefore scatter the energyscatter the energy
Interactions of Ultrasound Waves with Interactions of Ultrasound Waves with TissueTissue
The interactions will determine the types of The interactions will determine the types of images & artifacts that are generatedimages & artifacts that are generated
Reflection, Attenuation & Reflection, Attenuation & Time Gain Time Gain Conpensation Conpensation SettingsSettings
Transducer Frequency & Wavelength affect Transducer Frequency & Wavelength affect Resolution & PenetrationResolution & Penetration
TRANSDUCERSTRANSDUCERSDESIGNDESIGN
• Piezoelectric Principle is universal• Linear Array
Nerve Block probe
• Mechanical Sector Scan old Site Rite
• Phase Array Design• 3D probes
Mechanical Sector Scan
PHASE ARRAY TRANSDUCERGenerating the Summation Wave front
Steering the Phase Array Summation Wave Front
3D probes3D probes
Types of Ultrasound “Formats”
• A mode (amplitude)• B mode (brightness) Most common• M mode (motion) • Doppler
Pulse WaveContinuous WaveColor Flow
• 3D
A Mode (amplitude) B Mode (2D) M Mode A Mode (amplitude) B Mode (2D) M Mode (motion)(motion)
3D Format3D Format
• Fig 3.48 video.avi
SUMMARY• Understanding Echocardiography
Physics will enhance our understanding of:
• The physical principles that affect our measurements and images
• Knowing when to believe or doubt our results
• The strengths and limitations of the technology