The influence of bone model geometries on the determination of skull acoustic properties.
The influence of bone model geometries on the determination of skull acoustic properties.
复制标题
骨模型几何形状对颅骨声学特性测定的影响。
DOI：
10.1002/cnm.3779
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发表时间：
2023
影响因子：
2.1
通讯作者：
Christensen,DouglasA
中科院分区：
文献类型：
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作者：
Marchant,JoshuaK;Clinard,SamuelR;Odéen,Henrik;Parker,DennisL;Christensen,DouglasA
在这项研究中，我们研究了各种模拟颅骨几何形状的影响，通过优化使用传输的压力振幅超出骨的声音和声衰减值的头骨速度的确定。使用混合角谱方法（HAS），我们模拟了通过四个不同几何形状的模型集的超声传输，这些模型集包括板障和皮质骨的夹层以及从离体人类颅骨的CT图像生成的三个模型。我们表征了每个模型的成本函数解空间，并使用优化发现，当模型在可分辨层厚度方面具有明显变化时，可以以低误差（RMSE < 0.01 Np/cm）找到预定义的衰减系数。然而，我们在模型的几何结构中确定了空间频率截止，超过该空间频率截止，属性确定的准确性开始失效，这取决于超声源的频率。当层厚度的变化高于所识别的空间频率截止值时，或者当跨模型的横向变化幅度相对较低时，通过优化确定的衰减系数的误差大幅增加。对于我们有限的三个CT图像衍生骨模型样本，成功确定了衰减系数。对于所有受试模型（包括CT图像衍生模型），均以低误差确定声速值（RMSE < 0.4 m/s）。这些结果表明，当考虑内部骨结构并且结构满足所讨论的空间频率约束时，可以确定双组分模型的声学特性。
In this study, we investigated the impact of various simulated skull bone geometries on the determination of skull speed of sound and acoustic attenuation values via optimization using transmitted pressure amplitudes beyond the bone. Using the hybrid angular spectrum method (HAS), we simulated ultrasound transmission through four model sets of different geometries involving sandwiched layers of diploë and cortical bone in addition to three models generated from CT images of ex‐vivo human skull‐bones. We characterized cost‐function solution spaces for each model and, using optimization, found that when a model possessed appreciable variations in resolvable layer thickness, the predefined attenuation coefficients could be found with low error (RMSE < 0.01 Np/cm). However, we identified a spatial frequency cutoff in the models' geometry beyond which the accuracy of the property determination begins to fail, depending on the frequency of the ultrasound source. There was a large increase in error of the attenuation coefficients determined by the optimization when the variations in layer thickness were above the identified spatial frequency cutoffs, or when the lateral variations across the model were relatively low in amplitude. For our limited sample of three CT‐image derived bone models, the attenuation coefficients were determined successfully. The speed of sound values were determined with low error for all models (including the CT‐image derived models) that were tested (RMSE < 0.4 m/s). These results illustrate that it is possible to determine the acoustic properties of two‐component models when the internal bone structure is taken into account and the structure satisfies the spatial frequency constraints discussed.