Estimation and correction of ultrasonic wavefront distortion using pulse-echo data received in a two-dimensional aperture
Estimation and correction of ultrasonic wavefront distortion using pulse-echo data received in a two-dimensional aperture
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使用二维孔径中接收的脉冲回波数据估计和校正超声波波前畸变
DOI：
10.1109/58.660157
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
R. Waag
中科院分区：
文献类型：
--
作者：
Dalong Liu;R. Waag
来自随机散射和来自点目标的脉冲回波测量已被用于量化发射机波束大小效应和等晕块大小，以及评估不同像差补偿技术的性能。使用直径为1/2英寸、1英寸或2英寸的单元件发射器进行测量，每个发射器聚焦在3英寸处。模拟组织的散射模体或点目标被用来产生回波，这些回波在通过扫描线性阵列合成的二维孔径中被接收。将腹壁标本放置在接收路径中以产生像差。B扫描图像是在没有补偿的情况下形成的，在接收孔径中进行时移补偿，并在反向传播之后进行时移补偿。通过用原始点目标位置估计的参数补偿测试点目标的焦点，并观察随着测试点目标与原始点目标距离的增加补偿效果的恶化，来估计等晕块大小。使用不同发射机直径的测量结果量化了随发射机波束尺寸减小而增加的波前相干性对时延估计的改善。对于7个标本，通过-10dB有效直径增加10%确定的平均等平面斑块尺寸在方位向为16.7 mm，在射程方向为39.0 mm。回交后，上述两种大小分别增加到19.0 mm和41.4 mm。对于1/2英寸、1英寸和2英寸平均对比度提高2.0dB、2.1db和2.8dB时移补偿后，平均对比度提高2.3dB、2.7dB和3.5dB，后向传播20 mm，然后进行时延估计和补偿。研究表明，要产生满足时移估计要求的散射波前，需要一束紧聚焦的发射机光束，等距面片在距离方向上的长度大约是方位向的两倍，后向传播和时移补偿比单独的时移补偿提供了更好的失真补偿。
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.
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影响因子：
2.4
作者：
HINKELMAN, LM;LIU, DL;WAAG, RC
通讯作者：
WAAG, RC
影响因子：
2.4
作者：
LIU, DL;WAAG, RC
通讯作者：
WAAG, RC
使用到达时间的最小均方误差估计对超声脉冲焦点退化进行时移补偿。
DOI：
10.1121/1.408348
发表时间：
1994
期刊：
The Journal of the Acoustical Society of America
影响因子：
--
作者：
Liu,DL;Waag,RC
通讯作者：
Waag,RC
通过模型随机介质和小牛肝脏的散射测量来估计波前畸变。
DOI：
10.1121/1.397692
发表时间：
1989
期刊：
The Journal of the Acoustical Society of America
影响因子：
--
作者：
Waag,RC;Dalecki,D;Smith,WA
通讯作者：
Smith,WA
影响因子：
2.4
作者：
HINKELMAN, LM;LIU, DL;STEINBERG, BD
通讯作者：
STEINBERG, BD