The goals of this work are to quantify the acoustic energy balance between thermal and mechanical energies for typical ultrasound configurations used during diagnostic and therapeutic soft tissue insonification and to determine how those energies dynamically change after being absorbed by tissue. Insonification of tissue with ultrasonic frequencies leads to a complex dynamic balance between thermal and mechanical energies that persist on different time domains (10~(1) vs. 10~(-3) s) and vary appreciably in magnitude (10~(-3) vs. 10~(-9) J). Acoustic radiation force-based imaging modalities are able to take advantage of very small amounts of absorbed acoustic energy, compared with thermal energy, to generate strain fields in tissue. While the dynamic displacement behavior of focused, impulsive acoustic radiation force excitations are shear mediated, material properties such as Poisson's ratio can have a significant effect on the amount of mechanical energy that is coupled into the material.
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