Wear Keith A
US Food and Drug Administration, Center for Devices and Radiological Health, HFZ-142, 12720 Twinbrook Parkway, Rockville, Maryland 20852, USA.
J Acoust Soc Am. 2005 Aug;118(2):1186-92. doi: 10.1121/1.1940448.
Frequency-dependent phase velocity was measured in trabecular-bone-mimicking phantoms consisting of two-dimensional arrays of parallel nylon wires (simulating trabeculae) with thicknesses ranging from 152 to 305 microm and spacings ranging from 700 to 1000 microm. Phase velocity varied approximately linearly with frequency over the range from 400 to 750 kHz. Dispersion was characterized by the slope of a linear least-squares regression fit to phase velocity versus frequency data. The increase in phase velocity (compared with that in water) at 500 kHz was approximately proportional to the (1) square of trabecular thickness, (2) inverse square of trabecular spacing, and (3) volume fraction occupied by nylon wires. The first derivative of phase velocity with respect to frequency was negative and exhibited nonlinear, monotonically decreasing dependencies on trabecular thickness and volume fraction. The dependencies of phase velocity and its first derivative on volume fraction in the phantoms were consistent with those reported in trabecular bone.
在由平行尼龙丝二维阵列（模拟小梁）组成的骨小梁模拟体模中测量频率依赖性相速度，这些尼龙丝的厚度范围为152至305微米，间距范围为700至1000微米。在400至750千赫兹范围内，相速度随频率近似呈线性变化。通过对相速度与频率数据进行线性最小二乘回归拟合的斜率来表征频散。在500千赫兹时相速度的增加（与在水中相比）近似与以下因素成正比：（1）小梁厚度的平方，（2）小梁间距的平方反比，以及（3）尼龙丝所占的体积分数。相速度相对于频率的一阶导数为负，并且对小梁厚度和体积分数呈现出非线性、单调递减的依赖性。体模中相速度及其一阶导数对体积分数的依赖性与在骨小梁中报道的一致。
