Measurement of the Nonlinearity Parameter B/a in Biological Materials Using the Finite Amplitude and Thermodynamic Method
Law, Wing Kong
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https://hdl.handle.net/2142/69267
Description
Title
Measurement of the Nonlinearity Parameter B/a in Biological Materials Using the Finite Amplitude and Thermodynamic Method
Author(s)
Law, Wing Kong
Issue Date
1984
Department of Study
Electrical Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Acoustics
Abstract
It is well-known that materials exhibit a decrease in compressibility when subjected to high compression. This decrease in compressibility may be described by the nonlinearity parameter B/A. Organic liquids have been shown to possess a wide variation of the parameter, ranging from 5 to 12. This thesis reports on the measurement of this parameter in biological materials, including tissue models and soft tissue. An acoustic method with the potential for in vivo measurements is developed for this purpose. The result of measurements is confirmed by a second method which determines the change of sound speed, and hence the compressibility, with changes in hydrostatic pressure and temperature. The measurements indicate that: (1) B/A increases approximately linearly with solute concentration for protein solutions; (2) B/A is relatively insensitive to the molecular weight of the solute for a fixed concentration; (3) B/A ranges from 6.5 to 11 for various soft tissues; and (4) B/A decreases when the cellular structure of a tissue is destroyed. It is felt that details of nonlinear ultrasonic propagation in living systems should contribute to the development of clinical diagnostic and therapeutic applications of ultrasound.
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