超声柱面导波动态监测与评价骨折愈合过程的研究

项目名称： 超声柱面导波动态监测与评价骨折愈合过程的研究

项目编号： No.30870720

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 他得安

作者单位： 复旦大学

项目金额： 30万元

中文摘要： 采用超声导波评价长骨骨折及其愈合是近年来骨超声领域的研究热点和难点之一。本项目在理论、数值仿真和实验上研究了超声柱面导波(简称超声导波)在骨折长骨中的传播特性、在骨折处发生的模式转换规律、长骨骨折及其愈合过程的动态监测与评价等。 本项目把骨折长骨看作充粘液复合管状结构，采用理论、数值仿真(混合边界元法及时域有限差分法)及实验等，在不同的长骨骨折及其愈合情况下，主要研究了：(1)导波在骨折长骨中的传播特性；(2) 骨折检测的超声导波方法；(3) 骨折愈合过程的监测与评价。分析了导波各较低阶模式在愈合过程中骨折处的反射、透射及模式转换等关系；(4) 研究了骨折长骨中导波模式的激发和接收；(5) 导波模式的识别、提取和处理的时频分析方法；(6) 探讨了超声导波的应用及实现途径，建立了多参量综合评价骨折及愈合过程的导波方法。 结果表明：在低频下，低阶导波模式在高频散、低衰减的情况下，激发模式(如L(0,2))转化成新模式的能量不同，可根据接收信号中转换模式的能量大小及与激发模式能量的比值，来动态监测与评价骨折及其愈合情况。该结果为骨折及其愈合过程动态监测与评价提供了一种新思路和理论依。

中文关键词： 超声导波；数值方法；时频分析；骨折愈合；评价

英文摘要： The evaluation of fractured long bone and healing process has become an interesting topic in recent years. This project concentrates on the dynamic evaluation of fractured long bone in healing process using ultrasonic cylindrical guided waves, called "ultrasonic guided waves (GW)" for short. Based on the theoretical derivation, both simulation and experiments have been carried out to analyze the propagation of GW, especially modes conversion, in fractured long bone under different healing statuses. In the project, the fractured long bone was considered as a viscous pipe-shaped structure, which was modeled by boundary element method (BEM) and finite-difference time-domain (FDTD) method. Axial transmissions experiments were designed to investigate the influences of fractured statuses over GW propagation. The main progresses and studies include the followings: (1) GW propagation characteristics in fractured long bones; (2) Detection methods of bone fractures based on GW technique, (3) Dynamic monitoring and evaluation of healing process of the long bone by transmission and reflection coefficients, which is mainly focused on modes conversion phenomenon of low-order guided modes in different healing processes; (4) GW excitation and receive methods of fractured long bone evaluation; (5) Time-frequency signal analysis methods for modes identification and separation of GW; (6) The practicality of GW application, set up a multi-parameter GW method of bone fracture evaluation and healing during different statuses. In conclusion, it is illustrated that low-order guided modes with relatively high dispersion and less attenuation at low-frequency band, the energy ratio between converted and original modes (such as L(0,2)) can be adopted as indicators of bone fracture healing statuses. Narrow band excitation and modes separation methods play very important roles to overcome the dispersion property of GW. Those significant results provided foundation for the dynamic monitoring and evaluation of long bone fracture healing.

英文关键词： Ultrasonic guided waves; Numerical methods; Time-frequency analysis; Fracture healing; Evaluation