Giesey J J, Carson P L, Fitting D W, Meyer C R
Dept. of Electr. Eng., Ohio Univ., Athens, OH.
IEEE Trans Ultrason Ferroelectr Freq Control. 1992;39(2):167-73. doi: 10.1109/58.139111.
An experimental pulse-echo imager was developed for the purpose of reducing speckle in ultrasonic images. The system utilized a 64-element spherically focused segmented annuli array receiver with a common transmitter. Compounded images were formed using subapertures of varying size, shape, and overlap, and the speckle and resolution characteristics of the final images were observed. A pointlike scatterer was imaged to determine the resolution, point spread function, and sensitivity of the system along with a new measure called the resolution cell size. The response of the system was also simulated for comparisons. It was found that lateral resolution, and resolution cell sizes only gradually increased with a decrease in subaperture size and system sensitivity was not greatly diminished. Incoherent summation of signals from small groups of elements decreased the speckle noise by a factor of four while maintaining enough resolution to improve the image quality as measured by the CSR/d by a factor of almost two.
为了减少超声图像中的散斑，开发了一种实验性脉冲回波成像仪。该系统采用了一个带有共用发射器的64阵元球形聚焦分段环形阵列接收器。使用不同大小、形状和重叠的子孔径形成复合图像，并观察最终图像的散斑和分辨率特性。对一个点状散射体进行成像，以确定系统的分辨率、点扩散函数和灵敏度，以及一种名为分辨率单元大小的新度量。还对系统的响应进行了模拟以作比较。结果发现，横向分辨率和分辨率单元大小仅随着子孔径尺寸的减小而逐渐增加，并且系统灵敏度没有大幅降低。来自小单元组的信号的非相干求和将散斑噪声降低了四倍，同时保持了足够的分辨率，使得以CSR/d衡量的图像质量提高了近两倍。
