ECE 474 - Ultrasonic Techniques

Spring 2005

Ultrasonic TechniquesECE474L39330LEC3 -    Leon A Frizzell

Official Description

(ECE 374) Ultrasonic wave propagation, generation, detection, and measurement in liquid and solid media, acoustic impedance concepts, ultrasonic absorption and velocity measurement techniques, piezoelectricity, and discussion of industrial, experimental, bioengineering, and medical applications. Course Information: 3 undergraduate hours. 3 or 4 graduate hours. Prerequisite: ECE 473 or equivalent or consent of instructor.

Course Goals

This course is an elective for electrical engineering, computer engineering, theoretical and applied mechanics, and other majors. The goals are to provide fundamental understanding of ultrasonic systems to prepare electrical engineering, computer engineering, theoretical and applied mechanics, and other majors to take jobs involving the use of ultrasonic techniques or to conduct research in an area of ultrasonics. A particular emphasis is placed on the understanding of medical imaging systems.

Instructional Objectives

By completion of the course, the students should be able to do the following:

1. Define the basic building blocks of an ultrasonic imaging system and understand at a basic level the functioning of each. (a)

2. Observe and understand the ultrasonic image produced from a tissue mimicking ultrasound phantom. (a)

3. Acquire an initial understanding of the range of ultrasonic applications in medicine, research and industry. (a)

4. Understand the relationship between stress and strain in solids. (a)

5. Develop and understand the three-dimensional wave equation using stress, strain and the constitutive relations for solids. (a)

6. Determine the appropriate components of stress, strain and elasticity to describe propagation of longitudinal and shear waves in solids. (a)

7. Be able to simplify the relations in 5 and 6 above for the case of an isotopic material. (a)

8. Use 7 above to determine the third parameter given the other two involved in wave propagation in an isotropic medium. (a)

9. Calculate the transmission and reflection coefficients both for intensity and power at interfaces between two media. (a)

10. Calculate transmission coefficients in three layer systems and understand the special uses in various circumstances of interest in ultrasonic applications, such a the design of and acoustic window and an impedance matching layer. (a,c)

11. Define the contributions to attenuation from scattering and absorption, including the basics of scattering and the classical and relaxational absorption mechanisms. (a)

12. Be able to describe the frequency dependence of the absorption coefficient and the speed of sound when the different absorption mechanisms apply and the reasons for the different behavior. (a)

13. Define several different types of sources and receivers of ultrasound (transducers) and have some understanding of the circumstances under which the different transducers might be used. (a)

14. Be able to use the piezoelectric equations and material constants to describe the behavior of piezoelectric sources. (a)

15. Calculate the electrical impedance of different piezoelectric sources using the material properties and transducer dimensions. (a)

16. Explain the various advantages and disadvantages of particular materials when used as sources or receivers. (a)

17. Design a lens to provide focusing at a particular focal distance for a circular source transducer. (a,c)

18. Describe quantitatively the field pattern from an ultrasound transducer array. (a)

19. Understand the concept of grating lobes associated with arrays and ways that they can be minimized or eliminated. (a)

20. Be able to define the phase variations required to provide electronic focusing and steering with a linear or two dimensional phased array source. (a)

21. Define the basic requirements of systems used for medical therapy, including both hyperthermia and surgery. (a)

22. Be able to design a system that could be used for the applications in 21, for example with the gain required for treating deep tissues. (a,c,k)

23. Define in detail the role of the various components of an ultrasound medical imaging system. (a)

24. Calculate required dynamic range and overall gain for the design of an imaging system to be used at a specified frequency and depth. (a,c,k)

25. Calculate the resolution for an imaging system based on the transducer design and the frequency. (a)

26. The reverse of 25. Design a transducer that will provide a desired lateral resolution at a given frequency. (a,c)

27. Define how thermal and nonthermal mechanisms may be involved in the effect of ultrasound on tissues. (a)

28. Be able to calculate the approximate temperature rise, with no heat dissipation by blood, due to broad beam ultrasound exposure. (a)

29. Define how cavitation can be involved in biological effects and explain the role of nuclei and acoustic pressure in that process. (a)

30. Calculate resonance frequencies for free bubbles in water. (a)

31. Explain the types of bubble responses that can occur in the presence of ultrasound and their importance to biological effects, cleaning in industry and sonochemical applications. (a)

32. Describe different techniques for measuring ultrasonic propagation properties such as speed, attenuation coefficient and absorption coefficient in liquids, solids and biological tissues. (a)

33. Describe the basic operating principles of a scanning laser acoustic microscope and of a scanning acoustic microscope. Calculate speed using the interference mode of a scanning laser acoustic microscope. (a)

34. Define the differences between a surface acoustic wave and waves propagating in the bulk of the material. (a)

35. Explain nonlinear propagation and its significance to wave distortion, attenuation, beam profiles, and saturation. (a)

36. Define the wide range of applications of ultrasound in industry and explain the operation of some of the basic systems that are used. (a)

Last updated