Ultrasonic guided waves dispersion reversal for long bone thickness evaluation: A simulation study

It has been shown that ultrasonic guided waves have great potentials for long cortical bone evaluation. However, due to the multimodal dispersion, the received signals usually contain several mixed guided modes, which highly complicates the mode separation and signal processing. In the study, we showed that the use of dispersion reversal excitation allows the self-compensation of the dispersive modes in the long cortical bone. Two-dimension finite-difference time-domain (2D-FDTD) method was employed to simulate the propagation of two fundamental guided modes, symmetrical S0 and anti-symmetrical A0, in the long cortical bones. It was demonstrated that the pulse-like modes of S0 and A0 can be detected under the dispersion reversal excitations. The simulations also illustrated that the proposed dispersion reversal method can be used to evaluate the cortical thickness. Results are promising for the application of dispersion reversal method in ultrasonic assessment of the long cortical bone.