Spectral estimation for characterization of acoustic aberration.
Spectral estimation for characterization of acoustic aberration.
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DOI：
10.1121/1.1760799
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发表时间：
2004-07
期刊：
影响因子：
--
通讯作者：
T. Varslot;B. Angelsen;R. Waag
中科院分区：
文献类型：
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作者：
T. Varslot;B. Angelsen;R. Waag
描述了基于静止随机介质的声波后向散射的光谱估计，用于表征超声成像中的像差。估计的基本假设是：介质的相关长度比发射声脉冲的长度短，焦点周围存在足够大的等平面区域，并且后向散射可以建模为遍历随机过程。这项工作的动机是超声成像与像差校正。测量使用二维阵列系统进行，传感器元件为80 x 80，元件间距为0.6 mm。测量的f值为1.2，中心频率为3.0 MHz，带宽为53%。基于相邻波形相位差随频率的正交展开，采用鲁棒最小均方误差法从估计的交叉光谱中提取相对像差相位。通过组织模拟像差的随机散射测量估计的交叉光谱相位具有大约+/- 5度宽的置信带。相位和幅度都与从点散射体获得的参考特性很好地一致。
Spectral estimation based on acoustic backscatter from a motionless stochastic medium is described for characterization of aberration in ultrasonic imaging. The underlying assumptions for the estimation are: The correlation length of the medium is short compared to the length of the transmitted acoustic pulse, an isoplanatic region of sufficient size exists around the focal point, and the backscatter can be modeled as an ergodic stochastic process. The motivation for this work is ultrasonic imaging with aberration correction. Measurements were performed using a two-dimensional array system with 80 x 80 transducer elements and an element pitch of 0.6 mm. The f number for the measurements was 1.2 and the center frequency was 3.0 MHz with a 53% bandwidth. Relative phase of aberration was extracted from estimated cross spectra using a robust least-mean-square-error method based on an orthogonal expansion of the phase differences of neighboring wave forms as a function of frequency. Estimates of cross-spectrum phase from measurements of random scattering through a tissue-mimicking aberrator have confidence bands approximately +/- 5 degrees wide. Both phase and magnitude are in good agreement with a reference characterization obtained from a point scatterer.