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基于时域有限差分法(FDTD)建立了松质骨的超声背散射仿真系统,研究了骨小梁材料特性对超声背散射信号的影响。首次得到松质骨中的超声背散射系数(BSC)和积分背散射系数(IBC)随骨小梁材料参数(密度、拉梅常数、黏度系数及声阻抗系数)的变化关系。研究结果表明,IBC随骨小梁密度的增加而增加;BSC和IBC随拉梅常数的增加而增加、随第一黏度系数的增加而近似线性地减小,第二黏度的变化对背散射信号的影响很小;背散射参数随阻抗系数的增加而减小。说明松质骨中的超声背散射特性不仅受骨矿密度(BMD)和骨微结构的影响,还与骨小梁的材料参数密切相关。研究结果有利于理解松质骨中超声的背散射特性,对松质骨骨质状况的评价有一定帮助。
The ultrasonic backscatter simulation system of cancellous bone was established based on finite difference time domain (FDTD) method, and the effect of trabecular bone material properties on ultrasonic backscatter signal was studied. For the first time, the relationship between the ultrasonic backscatter coefficient (BSC) and integral backscatter coefficient (IBC) of cancellous bone with the material parameters of bone trabecula (density, Lame’s constant, viscosity coefficient and acoustic impedance coefficient) was obtained. The results showed that IBC increased with the increase of trabecular thickness; BSC and IBC increased with the increase of Lame’s constant, and decreased linearly with the increase of the first viscosity coefficient. The change of second viscosity affected the backscatter signal The effect of backscattering parameters decreases with the increase of the impedance coefficient. It is concluded that the ultrasonic backscatter in cancellous bone is not only affected by bone mineral density (BMD) and microstructure, but also closely related to the material parameters of trabecular bone. The results are helpful to understand the backscattering characteristics of cancellous bone in ultrasound and have some help on the evaluation of cancellous bone status.