富含高频的截面精确重建  

A field rich in high-frequency components being accurately reconstructed with our tomography algorithm

作　　者：韩彦[1] 宋一中[2] HAN Yan;SONG Yi-zhong(Experimental Teaching Center,Shandong University of Finance and Economics,Ji′nan 250014,China;Physical Department,Dezhou University,Dezhou 253000,China)

机构地区：[1]山东财经大学实验中心,山东济南250014 [2]山东德州学院物理系,山东德州253000

出　　处：《激光与红外》2019年第8期1002-1006,共5页Laser & Infrared

基　　金：国家自然科学基金项目(No.11604040)资助

摘　　要：应用非线性自适应自动追踪目标的迭代重建算法(NAIRT)重建富含高频的截面。选用圆柱形PVC管材模拟轴对称场,法向截面是PVC圆环,对于截面场来说,PVC材质圆环即是矩形脉冲信号。X-ray对PVC管法向透射,采集透射影像。对PVC法向切片,从透射影像中提取切片的投影信息,应用NAIRT反投影迭代重建。结果发现,PVC材质对X-ray的吸收系数大约是2.2~2.6;重建PVC环厚度是8个像素;外直径是96个像素;根据PVC管材的参数,计算的重建PVC环厚度相对于管直径误差为0.46%。对重建数据灰度化,结果发现,不论灰度级怎么量化,PVC环厚度均匀、恒定;边缘清晰、分明。意味着重建结果PVC材质环的数据十分陡峭,从信号角度分析,矩形脉冲信号得以精确重建。综合分析发现,NAIRT能够精确重建富含高频成分的截面。Our home-made nonlinear auto-adjusting iterative reconstruction technique(NAIRT)was used to reconstruct a field rich in high-frequency components.A piece of cylindrical PVC pipe was selected to simulate axisymmetric fields.Its normal cross sections are PVC rings.As far as reconstructed fields are concerned,PVC rings are their rectangular pulse signals.The PVC pipe was normally transmitted by X-rays,and the transmitting image,called projection,was recorded.The PVC pipe was sliced by normal direction.The relative projection data of each slice could be extracted out from the projection image easily.One slice′s projection data were directly inverse-projected for iterating reconstruction.The iterating algorithm used here is our home-made NAIRT.As results,the absorption coefficient of PVC to X-ray is about 2.2~2.6.The thickness of each PVC ring is 10 pixels,and its external diameter is 96 pixels.Based on PVC pipe parameters,the error of the reconstructed PVC ring′s thickness is about 0.46%relative to the pipe external diameter.The reconstruction data were transformed into grayscale image.As results,no matter how to quantize grayscales,the thickness of the PVC ring kept uniform and constant.The edges of rings show clear and distinct.This means that the reconstructed PVC rings are very steep in signal data.As far as signal analysis is concerned,the rectangular pulse signals of PVC rings were accurately reconstructed.Based on analysis above,we considered that,NAIRT could be competent to reconstructing a field rich in high-frequency components.

关 键 词：X射线透射 吸收谱 投影 滤波 层析 

分 类 号：O434.19[机械工程—光学工程]