Insana M F, Wagner R F, Brown D G, Hall T J
Department of Diagnostic Radiology, University of Kansas Medical Center, Kansas City 66013.
J Acoust Soc Am. 1990 Jan;87(1):179-92. doi: 10.1121/1.399283.
A method for estimating structural properties of random media is described. The size, number density, and scattering strength of particles are estimated from an analysis of the radio frequency (rf) echo signal power spectrum. Simple correlation functions and the accurate scattering theory of Faran [J.J. Faran, J. Acoust. Soc. Am. 23, 405-418 (1951)], which includes the effects of shear waves, were used separately to model backscatter from spherical particles and thereby describe the structures of the medium. These methods were tested using both glass sphere-in-agar and polystyrene sphere-in-agar scattering media. With the appropriate correlation function, it was possible to measure glass sphere diameters with an accuracy of 20%. It was not possible to accurately estimate the size of polystyrene spheres with the simple spherical and Gaussian correlation models examined because of a significant shear wave contribution. Using the Faran scattering theory for spheres, however, the accuracy for estimating diameters was improved to 10% for both glass and polystyrene scattering media. It was possible to estimate the product of the average scattering particle number density and the average scattering strength per particle, but with lower accuracy than the size estimates. The dependence of the measurement accuracy on the inclusion of shear waves, the wavelength of sound, and medium attenuation are considered, and the implications for describing the structure of biological soft tissues are discussed.
本文描述了一种估计随机介质结构特性的方法。通过对射频（rf）回波信号功率谱的分析来估计粒子的大小、数密度和散射强度。分别使用简单相关函数和包含剪切波效应的Faran精确散射理论[J.J. Faran，《美国声学学会杂志》23，405 - 418（1951）]对球形粒子的后向散射进行建模，从而描述介质的结构。使用琼脂中的玻璃球和琼脂中的聚苯乙烯球散射介质对这些方法进行了测试。采用适当的相关函数，可以以20%的精度测量玻璃球直径。由于显著的剪切波贡献，在所研究的简单球形和高斯相关模型下，无法准确估计聚苯乙烯球的大小。然而，对于玻璃和聚苯乙烯散射介质，使用球体的Faran散射理论，估计直径的精度提高到了10%。可以估计平均散射粒子数密度与每个粒子平均散射强度的乘积，但精度低于大小估计。考虑了测量精度对剪切波的包含、声波长和介质衰减的依赖性，并讨论了其对描述生物软组织结构的意义。
