多层球壳构件FBP重建差异化滤波设计与仿真
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摘要
针对高密度差多层球壳这一类特殊工件的CT检测技术研究,构建平行束CT投影及图像重建系统模型,开发建立CT研究软件平台,结合理论分析和仿真着重研究基于滤波反投影(FBP)理论重建图像的滤波处理方法。首先通过限定扫描方式使多层球壳截面的CT投影正弦图呈现空间区域性分布,结合图像分析和先验知识对其进行分割,再根据重建细节的频率特征和检测需求,对不同区域投影分别采用RL和SL函数进行针对性的滤波处理。仿真结果表明,相对于传统FBP算法中的单一函数滤波,所提出的分区域差异化滤波方法能够获得更好的图像重建效果。
Aiming at the CT detection technology research for multilayer spherical shell with great density difference, the parallel beam CT projection and image reconstruction system model were built and a software platform was developed. Combined with theoretical analysis and computer simulation, the filtering method of FBP theory for image reconstruction was focused on. A special scanning mode was limited to make the projection sinogram of multilayer spherical shell show a regional spatial distribution, which was divided up combined with image analysis and priori knowledge. Then, according to the frequency characteristic and reconstruction demand, RL and SL functions were respectively used to filter projection data of different regions. The simulation results show that the proposed method can obtain better image reconstruction results compared with the single function filter in the traditional FBP algorithm.
Aiming at the CT detection technology research for multilayer spherical shell with great density difference, the parallel beam CT projection and image reconstruction system model were built and a software platform was developed. Combined with theoretical analysis and computer simulation, the filtering method of FBP theory for image reconstruction was focused on. A special scanning mode was limited to make the projection sinogram of multilayer spherical shell show a regional spatial distribution, which was divided up combined with image analysis and priori knowledge. Then, according to the frequency characteristic and reconstruction demand, RL and SL functions were respectively used to filter projection data of different regions. The simulation results show that the proposed method can obtain better image reconstruction results compared with the single function filter in the traditional FBP algorithm.
引文
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[2]张朝宗,郭志平,王贤刚,等.计算机断层成像技术原理、设计、伪像和进展[M].北京:科学出版社,2005.(Zhang CZ,Guo ZP,Wang XG,et al.Computed tomography principle,design,artifacts and recent advances[M].Beijing,China:Science Press,2005.)
[3]范慧赟.CT图像滤波反投影重建算法的研究[D].西安:西北工业大学,2007.(FAN Huiyun.Research on Filtered Backprojection Algorithms of CT Image Reconstruction[D].Xian,China:Northwest Polytechnical University,2007.)
[4]庄天戈.CT原理与算法[M].上海:上海交通大学出版社,1992.(Zhuang TG.CT Principles and algorithms[M].Shanghai,China:Shanghai Jiaotong University Press,1992.)
[5]夏惊涛,王群书,马继明,等.高密度差多层球壳双能CT图像重建方法[J].强激光与粒子束,2015,27(4):044002(5).(Xia Jingtao,Wang Qunshu,Ma Jiming,et al.Study of Image Reconstruction Method of Dual Energy CT for Multilayer Spherical Shell With Great Density Difference[J].High Power Laser and Particle Beams,2015,27(4):044002(5).)
[6]张朝宗,郭志平,张朋,等.工业CT技术和原理[M].北京:科学出版社,2009.(Zhang CZ,Guo ZP,Zhang P,et al.The technology and principle of industrial CT[M].Beijing,China:Science Press,2009.)
[7]蔡玉芳,李丹,王珏.工业CT图像边缘伪影校正[J].强激光与粒子束,2013,25(3):755-761.(Cai Yufang,Li Dan,Wang Jue.Edge artifact correction for industrial computed tomography images[J].High Power Laser and Particle Beams,2013,25(3):755-761.)
[8]方黎勇,白金平,李辉,等.工业CT图像轮廓提取与优化系统设计[J].强激光与粒子束,2012,24(9):2207-2211.(Fang Liyong,Bai Jinping,Li Hui,et al.Design of contour extraction and optimization system of industrial computed tomography images[J].High Power Laser and Particle Beams,2012,24(9):2207-2211.)
[9]Lewitt R M.Reconstruction algorithms:Transform methods[J].Proc IEEE(S0018-9219),1983,71(3):390-408.
[10]Y J He,A Cai,J-A Sun.Multiorientation simulaneous computation of backprojection for tomographic image reconstruction[J].Electronics Letters(S0013-5194),1993,29(9):822-824.
[11]Daniel P K Lun,Tai-Chiu Hsung,W C Siu.On the convolution property of a new discrete radon transform and its efficient inversion algorithm[J].Proceedings IEEE International Symposium on Circuits and Systems(S1051-8215),1995,3:1892-1895.
[12]段黎明,邱猛,吴朝明.面向逆向工程的工业CT图像预处理系统开发[J].强激光与粒子束,2008,20(4):666-670.(Duan Liming,Qiu Meng,Wu Zhao ming.Development of industrial CT image pre-processing system for reverse engineering[J].High Power Laser and Particle Beams,2008,20(4):666-670.)