Numerical simulation of ultrasound transmission in cancellous bone

Numerical simulation of wave propagation is performed through 31 volumes of trabecular bone. These volumes were reconstructed from high synchrotron microtomography experiments and were used as the input geometry in a three-dimensional (3D) finite-difference simulation tool developed in our laboratory. The simulation algorithm accounts for propagation in both the saturating fluid and bone but absorption is not taken into account. Numerical predictions are consistent with experimental observations in trabecular bones : linear frequency dependence of attenuation, quasi-linear increase of attenuation and speed of sound with the bone volume fraction, negative phase velocity dispersion in most of the specimens, propagation of fast and slow waves depending on the orientation of the trabecular network with respect to the direction of propagation of the ultrasound. Moreover, the predicted attenuation is in close agreement with the experimental data obtained for the same specimens. Coupling numerical simulation with real 3D bone microarchitecture provides a powerful tool to investigate the physics of ultrasound propagation in trabecular structures.