流场超声层析成像中图像的迭代滤波反投影重建  

Iterative filtered back projection image reconstruction for ultrasonic tomographic flow field imaging

作　　者：柳建楠[1] 王浩源[1] 王伯雄[1] 崔园园[1] 

机构地区：[1]清华大学精密仪器系精密测试技术及仪器国家重点实验室,北京100084

出　　处：《光学精密工程》2014年第11期3136-3144,共9页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.11274199)

摘　　要：为提高流场超声层析成像的图像重建质量,提出了一种迭代滤波反投影图像重建算法。该算法借鉴联合迭代重建算法的原理,将滤波反投影算法引入迭代重建过程。首先,利用滤波反投影算法,通过投影数据残差重建误差图像对流场图像进行修正,实现图像的迭代重建。然后,通过优化迭代步长,使每步迭代后投影数据残差均取得极小值以便加快收敛速度。最后,基于流场连续、紧支撑分布的特点,在迭代重建过程中引入投影数据的细分内插和流场图像的圆域修正。实验表明:相比于滤波反投影算法,迭代滤波反投影算法可使理论流场重建的图像误差平均减少26%,流量误差由1.77%减小至±0.25%以内;程序运行时间为0.63s,仅为联合迭代重建算法的0.89%。该算法可实现对直管段内和单弯管下游实际流场的可靠重建,满足流场高精度实时成像的要求。To improve the image reconstruction resolution of ultrasonic tomographic flow field imaging,an iterative Filtered Back Projection （FBP） algorithm was proposed.On the basis of the Simultaneous Iterative Reconstruction Technique （SIRT）,the FBP algorithm was integrated into an iterative reconstruction process.With the FBP algorithm,an error image was reconstructed by the residual error of the projection data,then the flow field image was revised and the iterative reconstruction of the image was implemented.By optimizing the iteration step size,the residual error of the projection data for each iteration was minimized to improve the speed of convergence.Finally,according to the flow field characteristics in continuity and compact support,the projection data was interpolated and the flow field image was assigned a value of zero outside the circular domain.Simulation results indicate that the iterative FBP algorithm decreases the image error by 26％ and the volume flow rate error decreases from an average of-1.77％ to ±0.25％ as compared with the FBP algorithm.In addition,the computational time of the iterative FBP algorithm is just 0.63 s,only 0.89％ that of SIRT.In actual experiments,the iterative FBP algorithm can reconstruct the flow fields in a straight pipe and downstream of a 90° single bend with high reliability.It concludes that the iterative FBP algorithm implements the reconstruction of flow fields in real-time and higher accurate because of its good reconstruction resolution and high computational efficiency.

关 键 词：流场成像 超声层析 图像重建 迭代滤波反投影 联合迭代重建算法 

分 类 号：TB559[理学—物理] TP391[理学—声学]