Clinics in Medical Education

Online Courses

PHYSICS IN ULTRASOUND

PHYSICS IN ULTRASOUND

Upon completion of this course, learners will be able to:

  1. Describe the physics behind ultrasound, including properties of sound transmission, sound and tissue interaction, and the Doppler principle.
  2. Describe the structure and function of an ultrasound probe, the properties of different probes, and how to select a probe based on procedure.
  3. Use various Doppler modes: color flow, pulsed wave, continuous wave, to obtain ultrasound images.
  4. Use motion mode (M-mode) to obtain ultrasound images.
  5. Adjust image settings on an ultrasound machine.
  6. Optimize an ultrasound image: sector size, depth, gain, focus.

Module 1: Hemodynamics

This module provides foundational knowledge in ultrasound physics and hemodynamics through the following four instructional videos:

  1. Part I: Review of Hemodynamic Principles
  2. Part II: Chamber Pressure and Continuity Equation
  3. Part III: Aortic and Mitral Valve
  4. Part IV: Proximal Isovelocity Area Method

Learning Objectives

By the end of this module, learners will be able to:

  1. Explain fundamental hemodynamic principles including types of flow, energy gradients, and the pressure–flow relationship, and describe their relevance to cardiovascular physiology and pathology.
  2. Apply the principles of Doppler ultrasound physics including the Doppler shift, Nyquist limit, and aliasing to accurately assess blood flow dynamics and optimize imaging quality.
  3. Utilize key hemodynamic equations, such as the Bernoulli and continuity equations, to estimate pressure gradients, stroke volume, and cardiac output in clinical scenarios.
  4. Interpret non-invasive measurements of intracardiac chamber pressures and integrate these findings into clinical decision-making.
  5. Perform quantitative and semiquantitative assessments of valvular function, including aortic and mitral valve area calculations, and determine the severity of stenosis and regurgitation.
  6. Explain the theoretical basis and clinical application of the Proximal Isovelocity Surface Area (PISA) method for evaluating mitral stenosis and regurgitation.
  7. Integrate hemodynamic and Doppler principles to analyze case-based scenarios, enhancing diagnostic accuracy and clinical reasoning in cardiovascular ultrasound.

1. Part I: Review of Hemodynamic Principles

A. Core Hemodynamic Concepts

  1. Types of Flow
  2. Energy Gradient
  3. Pressure–Flow Relationship

B. Doppler Physics

  1. Doppler Shift
  2. Doppler Equation
  3. Pulse Wave Doppler
  4. Nyquist Limit
  5. Aliasing: Definition and Mechanism
  6. Strategies to Minimize Aliasing

C. Fundamental Concepts

  1. Relationship Between Flow and Pressure
  2. Relationship Between Velocity and Pressure

D. Key Formulae

  1. Bernoulli’s Equation

2. Part II: Chamber Pressure and Continuity Equation

  • Chamber Pressure Quantification Techniques
  • Application of Continuity Equations
  • Five Practical Case Examples Demonstrating Clinical Application

3. Part III: Aortic and Mitral Valve 

A. Aortic Valve

  • Calculation of Aortic Valve Area
  • Assessment of Aortic Stenosis Severity
  • Stroke Volume and Cardiac Output Calculation

B. Mitral Valve

  • Evaluation of Mitral Stenosis via Pressure Decline Method (Left Atrium)
  • Semiquantitative Assessment of Mitral Regurgitation Using the Vena Contracta Method

4. Part IV: Proximal Isovelocity Area Method

  • Principles Underlying the PISA Technique
  • Application of PISA in Quantifying Mitral Stenosis and Mitral Regurgitation

Module 2: Building Blocks and Core Principles

This module provides the foundational framework for understanding and applying ultrasound imaging and cardiovascular hemodynamics. It is divided into two parts, both of which emphasize clinical application:

  1. Part I
  2. Part II

Learning Objectives:

By the end of this module, learners will be able to:

  1. Explain the basic principles of physics relevant to ultrasonography and their impact on image acquisition and interpretation.
  2. Describe the operation of ultrasound machines (knobology) and apply image optimization techniques to enhance diagnostic accuracy.
  3. Interpret hemodynamic data using spectral Doppler and color flow Doppler.
  4. Apply the simplified Bernoulli equation to estimate pressure gradients in clinical practice.
  5. Explain the principle of conservation of energy as it relates to cardiovascular hemodynamics.
  6. Define pressure gradient and pressure recovery, and describe their implications for clinical measurements.
  7. Quantify intracardiac pressures using Doppler-derived parameters and understand their clinical significance.
  8. Use the continuity equation to assess valvular flow and function.
  9. Analyze and interpret case-based clinical scenarios to apply theoretical knowledge in practice.
  10. Reinforce understanding of core hemodynamic concepts through problem-based learning and clinical case questions.

1. Building Blocks and CORE Principles – Part I

  • Principles of Physics in Ultrasonography
  • Hemodynamic Interpretation
  • Image Optimization Techniques
  • Knobology (Ultrasound Machine Operation)
  • Spectral Doppler
  • Color Flow Doppler
  • Application Through Clinical Case Discussions

2. Building Blocks and CORE Principles – Part II

  • Application of the simplified bernoulli equation in clinical practice
  • Principle of conservation of energy in cardiovascular hemodynamics
  • Pressure gradient and the concept of pressure recovery
  • Quantification of intracardiac chamber pressures
  • Case-based practice questions to reinforce key concepts
  • Application of the continuity equation

Module 3: Basic Physics

  1. Part I – Acoustic Parameters
  2. Part II – Transducer Design and Impulse Formation / Transmission
  3. Part III – Real Time Imaging / Artifacts / Harmonics

Learning Objectives:

By the end of this module, learner will be able to:

  1. Describe the key acoustic parameters (e.g., frequency, wavelength, propagation speed) that govern ultrasound wave behavior.
  2. Explain the interactions between ultrasound waves and tissue, including mechanisms of attenuation and amplification.
  3. Define pulsed ultrasound characteristics such as pulse duration, spatial pulse length, pulse repetition period, and duty factor, and discuss their clinical significance.
  4. Describe the components and function of ultrasound transducers, including principles of impulse formation and beam anatomy.
  5. Differentiate among types of resolution (axial, lateral, temporal) and their implications for image quality.
  6. Explain the principles of real-time imaging, including system settings, focusing techniques, frame rate, and receiver functions (e.g., amplification, compensation, demodulation).
  7. Distinguish between output power and receiver gain and discuss how dynamic range affects image display.
  8. Identify and describe common ultrasound artifacts (e.g., lobe artifacts, range ambiguity, beam path errors) and understand how they arise and affect interpretation.
  9. Understand the principles of harmonic imaging, including tissue harmonics, contrast harmonics, and the role of the mechanical index.
  10. Apply the physical principles learned to optimize image acquisition and recognize technical limitations during ultrasound use in clinical practice.

1. Part I – Acoustic Parameters

A. Acoustic Parameters and Sound Wave Properties

  1. Period
  2. Frequency
  3. Amplitude
  4. Power
  5. Intensity
  6. Wavelength
  7. Propagation Speed

B. Sound–Tissue Interaction

  • Mechanisms of Attenuation and Amplification

C. Pulsed Ultrasound Parameters

  1. Pulse Duration
  2. Spatial Pulse Length
  3. Pulse Repetition Period
  4. Pulse Repetition Frequency
  5. Duty Factor

2. Part II: Transducer Design Impulse Formation / Transmission

A. Transducer Design

  • Structural components and functional principles of ultrasound transducers

B. Impulse Formation

  • Generation and transmission of ultrasound impulses
  • Anatomy and structure of an ultrasound beam

C. Resolution

  • Concepts of axial, lateral, and temporal resolution and their relevance to image quality

3. Part III: Real-Time Imaging / Artifacts / Harmonics

A. Real-Time Imaging

  • Principles of image formation in real time
  • Focusing techniques and their consequences
  • Fixed focusing methods
  • Impact of focusing on image resolution and field of view
  • System settings, frame rate, and their optimization
  • Multi-focus systems and line density adjustments
  • Key receiver functions:
    • Amplification
    • Compensation
    • Compression
    • Demodulation
  • Comparison of output power versus receiver gain
  • Understanding and application of dynamic range settings

B. Imaging Artifacts

  • Beam Dimension Artifacts
  • Lobe Artifacts
  • Beam width artifacts
  • Beam thickness artifact
  • Side lobe and grating lobe artifacts
  • Depth of origin artifacts
  • Speed of sound artifacts
  • Range ambiguity artifact
  • Beam path artifacts

C. Harmonic Imaging

  • Introduction to harmonic wave generation
  • Contrast harmonic imaging
  • Mechanical index and its relevance in harmonic imaging
  • Tissue harmonic imaging
  • Fundamental and harmonic imaging techniques

Module 4: Acoustic Principles

This module focuses on the foundational acoustic principles of ultrasound and includes the following three instructional videos:

  1. Properties of Sound
  2. Sound Tissue Interactions
  3. Formation of the Ultrasound Beam

Learning Objectives:

By the end of this module, learners will be able to:

  1. Review the basic physical properties of sound relevant to ultrasound, including frequency, wavelength, velocity, and amplitude.
  2. Describe how sound is transmitted through different media, particularly soft tissue.
  3. Understand how sound interacts with tissue through reflection, refraction, scattering, absorption, and attenuation.
  4. Explain how these interactions impact image quality and diagnostic interpretation.
  5. Understand how an ultrasound beam is formed and how its properties influence resolution and penetration.

1. Properties of Sound

  • Sound waves
  • Period
  • Frequency
  • Amplitude
  • Power
  • Intensity
  • Wavelength
  • Propagation speed

2. Sound Tissue Interaction

  • Scattering
  • Reflection
  • Refraction
  • Attenuation and amplification

3. Formation of Ultrasound Beam

  • Huygen’s Principle
  • Attenuation and amplification
  • Anatomy of an ultrasound beam
  • Linear phased array transducer
  • Multiple transmit foci
  • Beam dynamics

Module 5: Ultrasound System Components

This module explores how ultrasound transducers work and how they contribute to image generation. It includes the following two instructional videos:

  1. Transducer Design
  2. Receiver Functions

Learning Objectives:

By the end of this module, learners will be able to:

  1. Understand the structure and components of the ultrasound transducer.
  2. Explain how the transducer functions to generate and receive ultrasound waves.
  3. Describe how the transducer contributes to image formation through sound wave transmission and echo detection.
  4. Understand the role of the receiver in amplifying, filtering, and processing signals to create a usable image.

1. Transducer Design

  • Anatomy of a transducer
  • Transesophageal echo transducer
  • Backing material
  • Piezoelectric crystals
  • Matching layer
  • Lens
  • Linear and curvilinear arrays
  • Constraints

2. Receiver Functions

  • Amplification
  • Two Dimensional Gain
  • Compensation
  • Compression
  • Demodulation
  • Reject

Module 6: Image Quality and Enhancement

This module covers techniques to enhance image quality and common artifacts encountered in ultrasound imaging. It includes the following three instructional videos:

  1. Focusing
  2. Artifacts
  3. Harmonics

Learning Objectives:

By the end of this module, learners will be able to:

  1. Understand the principles of focusing in ultrasound imaging, including phased array, external, and internal focusing techniques.
  2. Identify and describe various types of ultrasound artifacts, including:
    • Beam width artifacts
    • Side lobe artifacts
    • Depth of origin artifacts
    • Speed of sound artifacts
    • Range ambiguity artifacts
    • Reverberation artifacts
  3. Explain how multiple reflection artifacts occur during transmission and receiving.
  4. Understand key pulse characteristics, including:
    • Pulse duration
    • Spatial pulse length
    • Pulse repetition period
    • Pulse repetition frequency
    • Duty factor
  5. Describe the role of harmonic imaging in improving image resolution and reducing artifacts.

1. Focusing

  • Phased Array Focusing 
  • External Focusing
  • Internal Focusing
  • Consequences of Focusing

2. Artifacts

  • Beam Width Artifacts
  • Beam Thickness Artifact
  • Side Lobe and Grating Lobe Artifacts
  • Depth of Origin Artifacts
  • Speed of Sound Artifacts
  • Range Ambiguity Artifact
  • Beam Path Artifacts
  • Reverberation Artifact

3. Harmonics

  • Transmit and Receive
  • Pulse Duration
  • Spatial Pulse Length
  • Pulse Repetition Period
  • Pulse Repetition Frequency
  • Duty Factor
  • Five Review Questions

Module 7: Operational Aspects

This module focuses on the practical and safety aspects of ultrasound imaging. It includes the following three instructional videos:

  1. Real-Time Imaging
  2. Image Display and Storage
  3. Biosafety

Learning Objectives:

By the end of this module, learners will be able to:

  1. Describe the principles and workflow of real-time ultrasound imaging.
  2. Review image display settings and understand options for image storage, including standard formats and archiving practices.
  3. Understand safe operation of ultrasound machines and optimize settings to minimize patient risk.
  4. Discuss ultrasound biosafety principles.
  5. Recognize the importance of thermal and mechanical indices in maintaining biosafety standards during scanning.

1. Real-Time Imaging

  • Temporal Resolution
  • Imaging Depth
  • Number of Pulses
  • Multi-Focus
  • Sector Size
  • Line Density
  • Two Review Questions

2. Image Display and Storage

  • Screen
  • Pixels
  • Analog and Digital
  • Processing

3. Biosafety

  • Risks
  • Temperature Elevation
  • Acoustic Cavitation
  • Transesophageal Echo
  • ALARA Principle

Module 8: Self-Assessment Questions

This final module offers a series of self-assessment tools designed to reinforce learning, evaluate understanding, and promote retention of key concepts covered in the previous modules.

1. Self-Assessment 1

2. Self-Assessment 2

3. Self-Assessment 3

4. Self-Assessment 4

5. Self-Assessment 5

6. Self-Assessment 6

7. Self Assessment 7