中国激光, 2011, 38 (12): 1204001, 网络出版: 2011-10-31
基于相位补偿的改进内窥超声合成孔径方法
An Improved Synthetic Aperture Technique Based on Phase Compensation for Endoscopic Ultrasonography
医用光学 超声内窥 合成孔径 相位补偿 互相关 距离弯曲校正 medical optics endoscopic ultrasonography synthetic aperture phase compensation cross correlation range curve correction
摘要
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0.2 mm和1.6 dB,证明了改进超声内窥合成孔径方法的有效性。
Abstract
This paper describes the application of an improved synthetic aperture technique based on phase compensation. This technique corrects the phase distortion of the echoes caused by ultrasound degradation to enhance the resolution of endoscopic ultrasonography. The degradation of the echoes in lateral and axial directions is investigated to obtain the impact of center frequency and lateral resolution caused by ultrasound degradation. Two different cross correlations are implemented to compensate the phase distortion in both lateral and axial directions. One is achieved in the form of segmented cross correlation in axial direction to evaluate the instantaneous change of phase. The other one is used to compensate the remnant phase distortion after range curve correction to enhance the performance of lateral pulse compression. The results of simulation indicate that phase compensation can improve the resolution and signal-to-noise ratio (SNR) of ultrasound images. The increases are 0.2 mm and 1.6 dB in resolution and SNR, respectively, compared with the uncompensated images. It can be concluded that phase compensation has the potential to enhance the resolution and SNR.
李明, 陈晓冬, 李妍, 郝云霞, 汪毅, 郁道银. 基于相位补偿的改进内窥超声合成孔径方法[J]. 中国激光, 2011, 38(12): 1204001. Li Ming, Chen Xiaodong, Li Yan, Hao Yunxia, Wang Yi, Yu Daoyin. An Improved Synthetic Aperture Technique Based on Phase Compensation for Endoscopic Ultrasonography[J]. Chinese Journal of Lasers, 2011, 38(12): 1204001.