A new approach concerning human calcis bone characterization. Biot´s theory implementation

This paper deals with a new ultrasonic method based on Biot´s theory to characterize bone-like porous media. For osteoporosis diagnosis, classical parameters such as the slope of the attenuation are both dependent on structure and density. Here, the authors are aiming at the identification of parameters related to the structure only. The Biot theory defines two characteristic frequencies, f_t and f_c , which depend on structural parameters of the porous medium, such as porosity or pores size. However, they are not in the ultrasonic range. The authors have empirically defined two other frequencies, associated with a change in velocity. These frequencies are thought to delimit a Biot high frequency range and a diffusive range. Hydroxyapatite ceramics, calibrated in pores size, have been used for experiments. They have similar mass densities but different pore size. The results provide very low Biot frequencies in water-filled ceramics but may be promising with oil-filled ceramics. The measured empirical frequencies F_phase and F_TF are found to be well correlated with pore size