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首页> 外文期刊>IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control >Estimation and correction of ultrasonic wavefront distortion using pulse-echo data received in a two-dimensional aperture
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Estimation and correction of ultrasonic wavefront distortion using pulse-echo data received in a two-dimensional aperture

机译：使用二维孔径中接收的脉冲回波数据估算和校正超声波波前畸变

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Pulse-echo measurements from random scattering and from a point target have been used to quantify transmitter beam size effects and isoplanatic patch size as well as to evaluate the performance of different aberration compensation techniques. Measurements were made using a single-element transmitter with a diameter of 1/2 in., 1 in., or 2 in., each focused at 3 in. A tissue-mimicking scattering phantom or a point target was used to produce echoes that were received in a two-dimensional aperture synthesized by scanning a linear array. A specimen of abdominal wall was placed in the reception path to produce aberration. B-scan images were formed with no compensation, with time-shift compensation in the receiving aperture, and with backpropagation followed by time-shift compensation. The isoplanatic patch size was estimated by compensating the focus of a test point target with the parameters estimated for an original point target position, and observing the deterioration of compensation effects with increasing distance between the test and the original point targets. The results of the measurements using different transmitter diameters quantify the improvement of time-delay estimation with the increase in wavefront coherence that accompanies decreased transmitter beam size. For seven specimens, the average isoplanatic patch size determined from a 10% increase in the -10 dB effective diameter was 16.7 mm in the azimuthal direction and 39.0 mm in the range direction. These sizes increased after backpropagation to 19.0 mm and 41.4 mm, respectively. For the 1/2 in., 1 in., and 2 in. diameter transmitters, the average contrast ratio improvement was 2.0 dB, 2.1 dB, and 2.8 dB, respectively, with time-shift compensation, and 2.3 dB, 2.7 dB, and 3.5 dB, respectively, with backpropagation of 20 mm followed by time-delay estimation and compensation. The investigation indicates that a tightly focused transmitter beam is necessary to create a scattered wavefront satisfactory for time-shift estimation, the isoplanatic patch is about twice as long in the range direction as in the azimuthal direction, and backpropagation followed by time-shift compensation provides better compensation of distortion than time-shift compensation alone.
机译：来自随机散射和来自点目标的脉冲回波测量已用于量化发射器光束尺寸效应和等平面斑片尺寸，以及评估不同像差补偿技术的性能。使用直径为1/2 in。，1 in。或2 in。的单元素发射器进行测量，每个发射器聚焦在3 in处。使用模仿组织的散射体模或点目标产生回波，在通过扫描线性阵列而合成的二维孔径中接收光。将腹壁标本放置在接收路径中以产生像差。 B扫描图像形成时不进行补偿，在接收孔中进行时移补偿，并在反向传播之后进行时移补偿。通过用针对原始点目标位置估算的参数补偿测试点目标的焦点，并观察随着测试与原始点目标之间距离的增加，补偿效果的恶化，来估算等平面斑块的大小。使用不同发射器直径的测量结果量化了随波前相干性增加（随发射器波束大小减小而增加）的时延估计的改进。对于七个样本，由-10 dB有效直径增加10％确定的平均等平面斑块尺寸在方位方向上为16.7 mm，在范围方向上为39.0 mm。反向传播后，这些尺寸分别增加到19.0 mm和41.4 mm。对于直径为1/2英寸，1英寸和2英寸的发射器，采用时移补偿后，平均对比度的改善分别为2.0 dB，2.1 dB和2.8 dB，以及2.3 dB，2.7 dB，和3.5 dB，分别反向传播20 mm，然后进行延时估计和补偿。研究表明，紧密聚焦的发射器光束对于产生满足时移估计要求的散射波阵面是必要的，等距斑块在射程方向上的长度约为方位角方向的两倍，而反向传播和时移补偿可提供比单独的时移补偿更好的失真补偿。

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