基于S变换的长骨超声导波特征速度参数研究

超声导波可以反映长骨的材料特性,为此提出采用S变换高分辨率，提取长骨中超声导波特征速度参数来反映骨骼的力学特性.该方法首先对长骨导波作S变换，在时频域用最大值法确定不同模式导波信号最大能量极值点对应的传播时刻，根据传播距离，计算超声不同模式导波的特征速度.仿真结果表明，特征速度与骨骼泊松比呈线性相关，对皮质骨厚度不敏感，可用于评估骨骼的泊松比.该方法不依赖于导波的先验知识，因此具有一定的实用价值.
Abstract：Ultrasonic guided wave can reflect the material properties of the long bone. The S transform with high-resolution features was proposed to extract the feature velocity in ultrasonic guided wave, and then to reflect the mechanical properties of long bone. Firstly, S transform was performed on the long bone guided wave. Then the maximum method was used to determine the propagation time corresponding to maximum energy extreme point in time-frequency domain. According to the propagation distance, the feature velocities of different modes in ultrasonic guided wave were calculated. The simulation results show that the feature velocities are linearly correlated to bone Poisson's ratio, and is insensitive to the thickness of cortical bones. Therefore, it can be used to evaluate the bone Poisson's ratio. In addition, the method does not rely on the prior knowledge of the guided wave so that it has a certain practical value.