Karaman M, Bilge H S, O'Donnell M
Dept. of Electr. and Electron. Eng, Baskent Univ., Ankara.
IEEE Trans Ultrason Ferroelectr Freq Control. 1998;45(4):1077-87. doi: 10.1109/58.710591.
Multi-element synthetic aperture techniques employing subaperture processing over successive firing steps can produce good image quality with simple front-end hardware but are susceptible to motion and phase aberration artifacts. We explore correlation processing using fully common spatial frequencies of overlapping subapertures to adapt beamforming for motion and phase aberrations. Signals derived from the subset of elements representing common spatial frequencies exhibit significantly higher correlation coefficients than those from signals computed using the entire subaperture. In addition, the correlation coefficient decreases linearly with subaperture separation for complete subaperture signals, but remains nearly constant with subaperture separation if only common spatial frequencies are used. Adaptive multi-element synthetic aperture imaging with correlation processing using fully common spatial frequencies is tested on experimental RF data acquired from a diffuse scattering phantom using a 3.5 MHz, 128-element transducer array. The results indicate that common spatial frequencies can be used efficiently for correlation processing to correct motion and phase aberration for adaptive multi-element synthetic aperture imaging.
采用在连续发射步骤上进行子孔径处理的多元素合成孔径技术，利用简单的前端硬件就能产生良好的图像质量，但容易受到运动和相位畸变伪影的影响。我们探索使用重叠子孔径的完全公共空间频率进行相关处理，以针对运动和相位畸变调整波束形成。从代表公共空间频率的元素子集中导出的信号，其相关系数显著高于使用整个子孔径计算的信号。此外，对于完整子孔径信号，相关系数随子孔径间距线性降低，但如果仅使用公共空间频率，则相关系数随子孔径间距几乎保持恒定。使用完全公共空间频率进行相关处理的自适应多元素合成孔径成像，在使用3.5 MHz、128阵元换能器阵列从漫散射体模采集的实验射频数据上进行了测试。结果表明，公共空间频率可有效地用于相关处理，以校正自适应多元素合成孔径成像中的运动和相位畸变。
