大直径回转体零部件壳体局部加速器CT检测  

Local Accelerator CT Testing of Large-Diameter Rotary Part Shells

作　　者：詹美娜 倪松 余海军 谢海霞 刘丰林[1,2] 谭辉[1,2] Zhan Meina;Ni Song;Yu Haijun;Xie Haixia;Liu Fenglin;Tan Hui(Industrial CT Non-Destructive Testing Engineering Research Center,Ministry of Education,Chongqing University,Chongqing 400044,China;Key Laboratory of Optoelectronic Technology&Systems,Ministry of Education,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学工业CT无损检测教育部工程研究中心,重庆400044 [2]重庆大学光电技术及系统教育部重点实验室,重庆400044

出　　处：《光学学报》2024年第22期131-143,共13页Acta Optica Sinica

基　　金：国家重点研发计划(2022YFF0706400);国家自然科学基金面上项目(62171067)。

摘　　要：针对大直径回转体零部件直径较大且内部存在高密度材料、缺陷通常位于壳体部位的特点,采用电子直线加速器作为射线源,提出一种多次局部源直线扫描计算机断层成像(mL-STCT)方法。mL-STCT通过旋转检测对象及偏置射线源和探测器,对检测对象壳体预估缺陷部位进行多次扫描,每次扫描移动射线源以采集不同角度的投影数据。通过分析mL-STCT投影数据在Radon空间的不同分布,确定了每次扫描物体的旋转角度及相关成像参数。仿真和模拟的物理扫描实验结果表明,相比于局部源直线扫描计算机断层成像(L-STCT)和切向计算机断层成像(TCT),mL-STCT在投影连续情况下对缺陷结构的恢复效果较好,重建图像具有较完整、清晰的轮廓。实验结果说明mL-STCT可以实现大直径回转体零部件壳体的局部CT成像检测,在实际检测中具有重要的应用价值。Objective Large-diameter rotary parts play a crucial role in various applications,and non-destructive testing(NDT)is essential for preventing catastrophic failures and reducing economic losses.Conventional X-rays cannot penetrate these parts due to their substantial size and high-density materials.Therefore,an electron linear accelerator is employed as the Xray source,typically at angles not exceeding 30°.Existing digital radiography(DR)systems and motion detection enable full-section scanning of these objects.However,such methods are time-consuming and costly,particularly when precise rotation of the object is required.Given the focus on detecting defects in the shell areas,such as tangentially distributed strip defects,it is advisable to perform localized computed tomography(CT)on the shell.To address this need,we have developed a new imaging method based on the existing accelerator imaging system,aimed at enabling localized CT of large-diameter rotary part shells.This method has significant practical application value.Methods To meet the detection requirements of large-diameter rotary parts,we propose a multi-scan local source translation CT(mL-STCT)method.In mL-STCT,the detector and X-ray source are offset on opposite sides of the object.During scanning,the detector and object remain fixed,while the X-ray source translates parallel to the detector to collect projection data from various angles.The detector's center is consistently aligned with the shell area under inspection.The mL-STCT involves scanning the estimated defect region multiple times by rotating the object and adjusting the positions of the X-ray source and detector.The rotation angle and other scan parameters are determined by analyzing the projection data distribution in Radon space.Due to the limited-angle and truncation issues inherent in the mLSTCT method,the simultaneous iterative reconstruction technique(SIRT)is employed for image reconstruction.Comparative experiments are conducted using local source translation CT(L-STCT)and tangential

关 键 词：成像系统 计算机断层成像 直线扫描 图像重建 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]