人跟骨体外时域声速测量对中心频率、带宽和渡越时间标记的依赖性。
The dependence of time-domain speed-of-sound measurements on center frequency, bandwidth, and transit-time marker in human calcaneus in vitro.
作者信息
Wear Keith A
机构信息
U.S. Food and Drug Administration, Center for Devices and Radiological Health, HFZ-140, Rockville, Maryland 20852, USA.
出版信息
J Acoust Soc Am. 2007 Jul;122(1):636-44. doi: 10.1121/1.2735811.
Time-domain speed-of-sound (SOS) measurements in calcaneus are effective predictors of osteoporotic fracture risk. High attenuation and dispersion in bone, however, produce severe distortion of transmitted pulses that leads to ambiguity of time-domain SOS measurements. An equation to predict the effects of system parameters (center frequency and bandwidth), algorithm parameters (pulse arrival-time marker), and bone properties (attenuation coefficient and thickness) on time-domain SOS estimates is derived for media with attenuation that varies linearly with frequency. The equation is validated using data from a bone-mimicking phantom and from 30 human calcaneus samples in vitro. The data suggest that the effects of dispersion are small compared with the effects of frequency-dependent attenuation. The equation can be used to retroactively compensate data. System-related variations in SOS are shown to decrease as the pulse-arrival-time marker is moved toward the pulse center. Therefore, compared with other time-domain measures of SOS, group velocity exhibits the minimum system dependence.
跟骨的时域声速（SOS）测量是骨质疏松性骨折风险的有效预测指标。然而，骨中的高衰减和频散会使透射脉冲产生严重畸变，从而导致时域SOS测量结果模糊不清。针对衰减随频率线性变化的介质，推导了一个方程，用于预测系统参数（中心频率和带宽）、算法参数（脉冲到达时间标记）和骨特性（衰减系数和厚度）对时域SOS估计值的影响。该方程通过来自仿骨体模和30个人体跟骨样本的体外数据进行了验证。数据表明，与频率依赖性衰减的影响相比，频散的影响较小。该方程可用于对数据进行追溯补偿。结果显示，随着脉冲到达时间标记向脉冲中心移动，SOS中与系统相关的变化会减小。因此，与其他时域SOS测量方法相比，群速度表现出最小的系统依赖性。
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