Syllabus
Home Teaching Research Medical Physics

 

 

Course Title

:

Diagnostic Ultrasound Physics

Course Code

:

MEPH 575

Credit Hours

:

3 (2 lectures + 1 lab)

Prerequisites

:

Graduate Standing

     

Course Description

This course will introduce medical physics students to the principles and methods in ultrasound imaging. Initial focus is on basic acoustics and fundamental sound-tissue interactions, including propagation speed, attenuation, reflection, and scattering. Single element and array transducers are described, along with methods for estimating beam profiles and beam widths. Principles of modern pulse-echo scanners, including gray scale, color flow, and spectral Doppler are described. Finally, acoustic output levels and biological effects and safety are discussed.

 

Textbook

Class notes will be provided.

 

References

* Fundamentals of Acoustics.  Kinsler [QC243.F86 2000]
* Essentials of Ultrasound Physics.  Zagzebski [RC78.7.U4 Z34 1996]
* Exposure Criteria for Medical Diagnostic Ultrasound. NCRP [RC78.7.U4 N37 1992]
* Biological Effects of Ultrasound: Mechanisms & Clinical Implications. NCRP [1983]
* Doppler Ultrasound and its Use in Clinical Measurement.  Atkinson [RC78.7.U4 A84 1982]
* Basic Physics in Diagnostic Ultrasound.  Rose [QC244.R66 1979]
* Diagnostic Ultrasonics.  McDicken [RC78.7.U4 M3 1975]

 

Teaching Tools

* Computer presentations

* Blackboard

* Transparencies

* Internet online courses

* Group discussions

* Tour of the ultrasound clinic at KFUPM Medical Center

 

Assessment

Activity Weight
Problem Sets 10%
Lab Reports 30%
First Exam 20%
Second Exam 20%
Final Exam 20%

 

Grading

 

Grade

Mark

A+ ≥89
A 82-88
B+ 75-81
B 68-74
C+ 61-67
C 54-60
D+ 47-53
D 40-46
F <40

 

Laboratory Content

Session

Experiment Title

1.

Introduction to Clinical Equipment

2.

Speed of Sound, Attenuation

3.

Nonlinear (B/A) Measurements

4.

Echo Signals

5.

Transducer Fields

6.

Image Formation

7.

B-mode Spatial Resolution

8.

B-mode Lesion Detection

9.

Clinical Equipment (Doppler, color)

10.

Acoustic Output

 

Detailed Topical Outline

1. Introduction, History, Clinical Equipment Overview

Course introduction. Historical overview covering early attempts to use ultrasound in diagnosis. Early equipment configurations and general principles of ultrasound equipment operation.

 

2. Plane Wave Ultrasound

Derivation of the one dimensional equation in a lossless medium. Harmonic solutions of the wave equation. Factors determining the speed of sound. Relationship between wave variables, such as particle displacement, acoustic pressure, and particle velocity. Intensity and energy density calculations.

 

3. Reflection and Transmission at Interfaces

Boundary conditions at planar interfaces. Amplitude reflection and transmission coefficients. Sound power reflection and transmission coefficients.

 

4. Propagation Through Tissue

Outline of methods for measuring speed of sound. Attenuation and absorption of sound waves in biological tissue. Experimental data on propagation speed in tissues. Dependence of sound speed on frequency, temperature, and tissue composition. Experimental data on attenuation and absorption of sound waves in tissues. Hypothesized mechanisms for absorption and attenuation. In vivo measurement methods and data in normal and abnormal tissue. Nonlinear propagation. Finite amplitude ultrasound. Equation of state. Waveform distortion. Definition of B/A. Values of B/A for tissues. Harmonic imaging on clinical scanners.

 

5. Single Element Transducers

Design and construction of single element transducers. Piezoelectric effect. Half wave resonance. Matching and backing layers. Effect on pulse duration and axial resolution. Spherical waves. Radiation from planar piston transducers, including axial solution, near field and far field characteristics and far-field directivity function. Methods for focusing single element transducers. Focused transducer beam patterns.

 

6. Transducer Arrays

Transducer array types, construction, advantages and disadvantages of arrays. Beam forming with array transducers. Rectangular aperture directivity functions. Focusing, apodization, expanding aperture.

 

7. Ultrasound Scattering

Mechanisms for ultrasonic scattering. Scattering cross-sections as they relate to acoustic measurements. Scattering versus frequency and angle. The backscatter coefficient. Methods for measuring backscatter coefficients for selected tissues and the relationship to tissue structure. Statistical properties of echo signals including origin of Rayleigh statistics.

 

8. Clinical B-mode Equipment

Overall operation. Pulse-receivers, TGC, dynamic range, and signal processing. Beam formers. A-mode, B-mode, and M-mode. Scanning methods including sequential arrays, phased arrays, mechanical scanners, and water bath scanners. Image storage and recording. Scan conversion. Interpolation algorithms.

 

9. Doppler Ultrasound and Color Flow Imaging

The Doppler effect. Continuous wave Doppler equipment. Quadrature detection for directional Doppler. Pulsed Doppler. Aliasing and maximum detectable velocity versus depth. Spectral analysis. Examples of applications including deriving physiological parameters, estimating qualitative flow characteristics, and quantifying flow. Methods for deriving color flow images including Doppler processing and time-domain correlation. Quantifying flow with color flow imaging. Contrast agents in ultrasound.

 

10. Resolution, Performance Testing, Image Artifacts

Image artifacts including reverberations, refraction, shadowing, enhancement. Image texture. Rayleigh distribution and other statistical properties of texture. Geometric accuracy. Axial, lateral resolution, slice thickness. Rayleigh criteria. Lesion resolution. Source of image contrast on B-mode images. Detectability of masses versus object-backscatter contrast, size, and depth.

 

11. Examples of use in the clinic including echocardiography, obstetrical ultrasound, and abdominal ultrasound.

 

12. Specification of Acoustic Output Levels

Definitions of acoustic output quantities including acoustic power, peak compressional and rarefactional pressure amplitude. Time average, pulse average and temporal peak intensities. Spatial average and spatial peak intensities. Measurement methods including radiation force balances, hydrophones, and scanning apparatus. Typical output levels as a function of operating mode.

 

13. Biological Effects and ALARA

Mechanisms by which ultrasound waves induce biological effects including cavitation, thermal, and "direct" effects. In vitro effects, In vivo animal experiments. Risk versus benefit considerations. Thermal and mechanical indices.

 

Course Content

Session

Topic

1.

Introduction, History, Clinical Equipment Overview

2.

Plane Wave Ultrasound in a Lossless Medium

3.

Relationship Between Wave Variables

4.

Boundary Conditions at Planar Interfaces

5.

Reflection and Transmission Coefficients

6.

Attenuation and Absorption in Tissue

7.

Nonlinear Propagation

8.

Design and Construction of Single Element Transducers

9.

Axial Resolution

10.

Focusing Single Element Transducers

11.

Transducer Array Types

12.

Beam Forming with Array Transducers

13.

Mechanisms of Ultrasound Scattering by Tissue

14.

Methods of Measuring Backscatter Coefficients

15.

Statistical Properties of Echo Signals

16.

Scanning Methods

17.

Clinical B-Mode Equipment

18.

Continuous and Pulsed Doppler Ultrasound

19.

Spectral Analysis and Deriving Physiological Parameters

20.

Color Flow Imaging

21.

Image Artifacts

22.

Resolution and Image Contrast

23.

Echocardiography

24.

Obstetrical and Abdominal Ultrasound

25.

Acoustic Output Quantities

26.

Measurement Methods

27.

Biological effects of Ultrasound

28.

Review