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提出一种基于相位补偿的改进内窥超声合成孔径方法,校正因超声波衰减造成的回波相位失真,提高系统的分辨率。分析了超声回波在人体内部传播过程中产生的纵向与横向衰减,得到回波衰减与超声波中心频率及合成孔径系统横向分辨率的变化关系;采用纵向分段互相关的方法估计衰减引起的纵向回波的中心频率变化,补偿超声波波长变化造成的横向回波相位畸变;并对距离弯曲校正后的横向回波进行横向互相关,补偿距离弯曲校正后残留的距离弯曲量,改善横向匹配滤波器的脉冲压缩效果。仿真与实验结果表明,经纵向与横向二维相位补偿后,系统的横向分辨率和信噪比较未加补偿时分别提升了0.2mm和1.6dB,证明了改进超声内窥合成孔径方法的有效性。
An improved endoscopic ultrasonic synthetic aperture method based on phase compensation is proposed to correct the echo phase distortion caused by ultrasonic attenuation and improve the resolution of the system. The longitudinal and transverse attenuation of ultrasonic echoes propagating in the human body are analyzed. The relationship between the echo attenuation and the ultrasonic center frequency and the transverse resolution of the synthetic aperture system is analyzed. The longitudinal segmentation cross-correlation method is used to estimate the longitudinal Compensates the transverse echo phase distortion caused by the change of the ultrasonic wavelength, and transversely corrects the horizontal echo after the distance bending correction to compensate the residual distance bending amount after the distance bending correction, and improves the horizontal matched filter Pulse compression effect. Simulation and experimental results show that the horizontal resolution and signal-to-noise ratio of the system are improved by 0.2mm and 1.6dB, respectively, after compensating for longitudinal and transverse two-dimensional phase, which proves the effectiveness of the improved endoscopic synthetic aperture method Sex.