基于改进卷积反投影模型的CT成像伪影消除方法
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摘要
针对传统卷积反投影法的CT重建图像容易产生伪影的问题,提出了一种基于改进卷积反投影算法的CT成像伪影消除方法.该方法通过分析给定模板的测量参数,标定CT系统的旋转中心、探测器间距及各探测方向等参数,使用Radon和傅里叶变换得到反投影方程,并利用卷积反投影技术得到每一点的吸收率与投影值的积分关系,使用三次样条插值算法得到较清晰的重建图像.仿真结果表明,所提出的算法具有简明易懂、操作方便和精确度高等诸多优点,相较于传统方法拥有更高的运算效率.
Focusing on the fact that the CT reconstruction image obtained with the traditional convolution back projection method is easy to produce artifacts,an artifact elimination method for the CT imaging based on improved convolution back projection algorithm was proposed. Through analyzing the measurement parameters of a given template,such parameters as the rotation center,detector spacing and detection direction of CT system were calibrated,and the back projection equation was obtained through Radon and Fourier transformation. In addition,the integral relationship between the absorption rate and projection value of each point was obtained with the convolution back projection technique,and the clear reconstructed image was obtained with the cubic spline interpolation algorithm. The simulation results showthat the proposed algorithm has many advantages,such as concise and easy understanding,easy operate and high precision,and has a higher computational efficiency than traditional methods.
Focusing on the fact that the CT reconstruction image obtained with the traditional convolution back projection method is easy to produce artifacts,an artifact elimination method for the CT imaging based on improved convolution back projection algorithm was proposed. Through analyzing the measurement parameters of a given template,such parameters as the rotation center,detector spacing and detection direction of CT system were calibrated,and the back projection equation was obtained through Radon and Fourier transformation. In addition,the integral relationship between the absorption rate and projection value of each point was obtained with the convolution back projection technique,and the clear reconstructed image was obtained with the cubic spline interpolation algorithm. The simulation results showthat the proposed algorithm has many advantages,such as concise and easy understanding,easy operate and high precision,and has a higher computational efficiency than traditional methods.
引文
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[13]黄建龙.双跨孔距兰姆波层析成像无损检测算法研究[D].成都:电子科技大学,2014.(HUANG Jian-long.Research on nondestructive detection algorithm of double span rimw ave tomography[D].Chengdu:University of Electronic Science and Technology of China,2014.)
[14]李篪.一种基于图像处理的打捆钢筋计数方法[J].沈阳工业大学学报,2016,38(5):551-554.(LI Chi.A counting method for bundled steel bars based on image processing[J].Journal of Shenyang University of Technology,2016,38(5):551-554.)
[15]Wang Z W,Qiang Y U,Shu C M,et al.The simulation of CT filtering projection reconstruction using computer[J].Chinese Journal of M edical Physics,2010,7:152-159.
[16]Caruso D,de Cecco C N,Schoepf U J,et al.Correction factors for CT coronary artery calcium scoring using advanced modeled iterative reconstruction instead of filtered back projection[J].Academic Radiology,2016,23(12):1480-1489.
[2]高敦堂,谈平,葛文建.卷积法重建图象及在非线性参量成象中的应用[J].南京大学学报,1992,28(4):543-550.(GAO Dun-tang,TAN Ping,GE Wen-jian.Convolution reconstruction image and its application in nonlinear parametric imaging[J].Journal of Nanjing University,1992,28(4):543-550.)
[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 Hui-yun.Research on CT image filtering back projection reconstruction algorithm[D].Xi’an:Northw estern Polytechnical University,2007.)
[4]卞晓月,武妍.基于CT图像的肺实质细分割综合方法[J].重庆邮电大学学报(自然科学版),2010,22(5):665-668.(BIAN Xiao-yue,WU Yan.A method of careful lung segmentation based on CT images[J].Journal of Chongqing University of Posts and Telecommunications(Natural Science Edition),2010,22(5):665-668.)
[5]Fahlenkamp U L,Diaz R I,Wagner M,et al.Image quality of low-radiation dose left atrial CT using filtered back projection and an iterative reconstruction algorithm:intra-individual comparison in unselected patients undergoing pulmonary vein isolation[J].AC-TA Radiologica,2017,11:87-99.
[6]Park J H,Kim B,Kim M S,et al.Comparison of filtered back projection and iterative reconstruction in diagnosing appendicitis at 2-mSv CT[J].Abdominal Radiology,2016,41(7):1227-1236.
[7]宁祎,高红伟.脑外科CT图像的综合边缘提取算法[J].电子设计工程,2011,19(24):146-149.(NING Yi,GAO Hong-wei.An integrated algorithm of edge detection of brain surgery CT image[J].Electronic Design Engineering,2011,19(24):146-149.)
[8]辛山.基于γ射线CT及ECT的气液两相流成像系统[D].天津:天津大学,2011.(XIN Shan.Gas liquid two phase flow imaging system based on gamma ray CT and ECT[D].Tianjin:Tianjin University,2011.)
[9]郑德伟.连续太赫兹波层析成像实验研究[D].成都:电子科技大学,2011.(ZHENG De-wei.Experimental study of continuous terahertz tomography[D].Chengdu:University of Electronic Science and Technology of China,2011.)
[10]谌湘倩,马绍惠,须文波.基于有序子集加速拆分算法的三维CT图像重建[J].现代电子技术,2016,39(6):104-107.(CHEN Xiang-qian,MA Shao-hui,XU Wen-bo.Three-dimensional CT image reconstruction based on accelerated splitting algorithm of ordered subsets[J].M odern Electronics Technique,2016,39(6):104-107.)
[11]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):169-173.(XIA Jing-tao,WANG Qun-shu,MA Ji-ming,et al.High density differential multi-layer spherical shell double energy CT image reconstruction method[J].Strong Laser and Particle Beam,2015,27(4):169-173.)
[12]郭禹姬.虚拟相控阵超声散射CT成像中散射源快速定位及识别方法研究[D].太原:中北大学,2010.(GUO Yu-ji.Research on fast location and recognition of scattering sources in CT imaging of virtual phased array ultrasonic scattering[D].Taiyuan:North Central University,2010.)
[13]黄建龙.双跨孔距兰姆波层析成像无损检测算法研究[D].成都:电子科技大学,2014.(HUANG Jian-long.Research on nondestructive detection algorithm of double span rimw ave tomography[D].Chengdu:University of Electronic Science and Technology of China,2014.)
[14]李篪.一种基于图像处理的打捆钢筋计数方法[J].沈阳工业大学学报,2016,38(5):551-554.(LI Chi.A counting method for bundled steel bars based on image processing[J].Journal of Shenyang University of Technology,2016,38(5):551-554.)
[15]Wang Z W,Qiang Y U,Shu C M,et al.The simulation of CT filtering projection reconstruction using computer[J].Chinese Journal of M edical Physics,2010,7:152-159.
[16]Caruso D,de Cecco C N,Schoepf U J,et al.Correction factors for CT coronary artery calcium scoring using advanced modeled iterative reconstruction instead of filtered back projection[J].Academic Radiology,2016,23(12):1480-1489.