Effect of ultrasound attenuation on piezoelectric signal generation in cancellous bone

The piezoelectric signals generated in cancellous bone by ultrasound irradiation were numerically simulated using a piezoelectric finite-difference time-domain method. The changes of the piezoelectric signals with the cancellous bone thickness were investigated with the changes of the transmitted ultrasound signals. In the ultrasound direction of the strong trabecular orientation, two piezoelectric signals could be observed and was associated with the fast and slow waves in the ultrasound signal. The former wave amplitude did not vary with the thickness. The later wave amplitude randomly varied, but not significantly. In the ultrasound direction of the weak trabecular orientation, the piezoelectric signal due to the overlapped fast and slow waves and its multiple reflected wave could be observed. The former wave amplitude did not vary with the thickness. In both ultrasound directions, the local piezoelectric signal generated at the shallow depth of cancellous bone was dominant, which was because of the high ultrasound attenuation.