Role of absorption mechanisms for ultrasound attenuation in cancellous bone: Macroscopic modeling and experiment.

Abstract

Evaluation of the relative contribution of physical mechanisms responsible for attenuation of ultrasonic wave in cancellous bone is one of the crucial issues from the point of view of modeling elastic wave propagation and related model-based identification of the structural and mechanical properties of bone material. Considering trabecular bone as a porous material filled with fluid, the wave attenuation may stem from (i) intrinsic absorption in the fluid and solid phase, (ii) friction at the fluid-solid interface, as well as (iii) wave scattering by inhomogeneities (pores/trabeculaes). The commonly used for modeling ultrasound propagation in cancellous bone of the macroscopic Biot’s theory will be discussed in context of its potential applicability for prediction of wave parameters: phase velocity and attenuation coefficient as functions of frequency. Since the model was introduced for long wavelength range, the scattering effects are neglected, and the analysis will be focused on the absorption mechanisms responsible for attenuation of ultrasonic waves in bone material. The suitability of the model will be verified by comparison of results of sensitivity analysis of the model with in vitro experimental ultrasonic data obtained for cancellous bones filled with different fluids.