New Features of SIMTech s Unique CT Reconstruction and Visualization Software

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1 New Features of SIMTech s Unique CT Reconstruction and Visualization Software Liu Tong and Jiang Ting Ying More info about this article: Abstract Singapore Institute of Manufacturing Technology tliu@simtech.a-star.edu.sg Over the years, based on our inventions for automatic central ray determination for CT scan and differential CT reconstruction algorithm, an affordable software package for CT reconstruction, visualization and measurements has been developed and improved by continuously adding on new functions according to industry s requirements for convenient and reliable analysis of various applications. This paper will describe the main functions of this software, with attention mainly focusing on its unique features and their performance in actual industrial case studies, including reconstruction along arbitrary orientation, multiple reconstructions of a scan, realignment of top views to a preferred direction, various measurements and so on. Keywords: X-ray imaging, computed tomography, reconstruction software 1 Introduction In CT inspection industry, there are several reconstruction and visualization software packages that dominate the market. These software packages are powerful in terms of various functions and convenience they provide, however, they are also very expensive. Based on SIMTech inventions for automatic central ray determination [1] for CT scan and differential CT reconstruction algorithm [2-5], we have developed an affordable software package for CT reconstruction, visualization and dimensional measurements. Unlike all those commercially available software, many measurement and analysis functions of this software are developed based on the unique capability of well-oriented differential reconstruction. Over the last few years of extensive testing with real industrial applications, this software is now proven to be an efficient, low-cost, user-friendly tool that can meet most daily CT inspection and analysis of industrial applications for reconstruction, visualization, measurement and analysis. Differential reconstruction can be treated as a modifcation to the traditional FDK algorithm for an effective reconstruction to planar objects [1-4]. Traditional FDK reconstruction algorithm in computed tomography (CT) always uses a cubic reconstruction volume, regardless of the particular object shape. This becomes inefficient when reconstructing planar objects such as IC chips which have a large areato-thickness ratio. Differential reconstruction algorithm was developed to address this issue. Instead of using a cubical volume, an NxMxN (the value of M depends on the actual thickness of the object) volume is defined for reconstructing a planar object based on a generally automatical determinition of the scan-start-angle, axial-tilt-angle, and the location and projection thickness of the object in a [ID196] 1

2 particular scan. The main advantages of this method are the well-orientation reconstruction or the object regardless of its original mounting orientation, and the higher-resolution in the thickness dimension with even a smaller reconstruciton volume, when compared to the traditional method. This software includes several unique technologies, such as Automatic central-ray determination Differential planar reconstruction Differential reconstruction along any orientation-of-interest on an objet Figure 1: Illustration of Planar CT reconstruction with traditional and differential reconstructions Besides, this software is developed with the consideration that all the functions and features can be easily learned and used by general users who can quickly catch the problem of the part under inspection as well as obtain the wanted measurement and analysis results. 2 Key features of the software The functions of the software can be grouped into seven categories: Load/save image View both X-ray image and reconstructed images Parameters setting Reconstruction control Image enhancement Measurement 3D visualization [ID196] 2

3 Figure 2: Software interface The software is currently compatible to several brands of CT systems such as DAGE, YXLON, and can be further extended to other CT models. 3. New features of the software after last publication As some of the main technologies and functions have been published before [6], here we will only report those new features of our software developed based on our new understanding and experiences gained over the years of extensive services to industries. 3.1 Reconstruction with fine-tuned orientation parameters Our reconstruction module allows user to choose either conventional reconstruction method (used by almost all commercial CT software) or SimTech differential reconstruction method. When choosing the later, an object will be reconstructed along a specified orientation that is perhaps the primary plane of the object, or one of its internal feature planes. Now this capability is further enhanced to handle more complicated situations where precise determination of an orientation-of-interest is not achievable with the existing algorithm. As shown in figure 3, one electronic device is reconstructed with an orientation that is not ideal for interpretation and measurement (a small tilting still exists). To solve this problem, two supplementary angles are introduced to the scan-start-angle (SSA) and the axial-tilt-angle (ATA), [ID196] 3

4 These two parameters can be measured respectively using the axial view and frontal view (figure 3(c)). Then a 2 nd reconstruction can be conducted with all other parameters determined in the 1 st reconstructed unchanged. The results of the 2 nd reconstruction are shown in figure 3(c). (c) Figure 3: Reconstruction orientation improvement through fine-tuning SSA and ATA. 1 st reconstruction showing slightly tilted object; Determing the compensation angles for SSA and ATA; (c) 2 nd reconstruction results with the compensated SSA and ATA [ID196] 4

5 3.2 Multiple reconstruction of a scan This software allows one to conduct various reconstruction with a scan. This is a function only achievable with our unique differential reconstruction technology and its associated flexibility to reconstruct along any orientation-of-interest. To demonstrate this function, a dummy sample is fabricated with three CFRP plates, with each of them having different orientation. With the scan data of the sample, one can choose to reconstruct the whole object (either in conventional manner or using the differential reconstruction method), or reconstruct each of the three plates along its own orientation with the differential CT option. The four reconstruction results, as shown in figure 4, can be saved independently and reloaded for subsequent analysis. (c) (d) Figure 4: Reconstructions of the whole CFRP sample, and (c)-(d) each individual plate. The white letters were written on the surfaces of the plates with an ink-correction pen. 3.3 Realignment of top views to a user-preferred direction One key benefit of the differential reconstruction is the ability to obtain a well-orientated reconstruction of an object with even a smaller reconstruction volume and a higher resolution on the thickness dimension of the object, regardless of its actual mounting orientation at the start of the scan. This method, however, is unable to rectify the tilting of the primary plane (top view). In daily inspection application, we frequently encounter applications that expect cross-sectional images that may not align [ID196] 5

6 with any primary dimension of the object. In this situation, a function to perform a rotation to the CT data is necessary. A new function is now added to address this requirement, with which, an angle is first measured on the top-view for the preferred plane of interest. Then all CT data will be rotated by this angle so that the new axial images would become the cross-sectional images aligned to the plane of interest (figure 5) (c) (d) Figure 5: Realignment of the top views to obtain images of the cross-section of interest. Reconstruction results; Measurement of the plane-of-interest with respect to the topview axes; (c) Align the top-view to the plane-of interest; (d) One of the new axial images show the features on the cross-section of interest. 3.4 Quick zooming around any region-of-interest As the size of the image display box is smaller than the size of views, zooming capability is necessary to show the details of features. Convenience and fast zooming around any region-of-interest are the major consideration when designing the zoom function. When activating the zoom function, one can set a zoom factor by either directly entering a number or dragging the left scroll bar under the large display box. By default, the image is zoomed around the center of the image. By clicking a point on the full image in the left column [ID196] 6

7 of views, a rectangle indicating the actual ROI to be zoomed appears and that ROI is shown in the large display box (figure 6). The same procedure is true for all three orthogonal views of the CT data. Figure 6: Zooming of the regions-of-interest on a top view. Original views; Zooming of ROI in the rectangle indicated on the middle image of the left column; Zooming of another ROI in the rectangle indicated on the middle image of the left column; (c) 3.5 3D visualization module Even though our reconstruction software and the associated 2D slices based analysis and measurement capabilities are sufficient to address the majority requirements of industries for CT inspection applications, it is always useful to have a basic 3D visualization module. The 3D visualization module is now integrated to the software, which can be run on a general lab PC with the following specs: OS: 64bit Windows 10 Pro; CPU: Intel Broadwell CPU or newer, 1.7GHz, Video card: OpenGL compatible with 512MB; Memory: 6GB It provides two key functions of 3D visualization (figure 7): 3D rendering of CT data 3D rotation of object 3D clipping in arbitrary direction [ID196] 7

8 Figure 7: 3D visualization module. Rendering; Clipping 4 Conclusion As a cost-effective alternatvie to those expensive CT visualization software, SIMTech s PowerRecon CT reconstruction and visualization software has many unique features that could not be achieved (or is very diffifuclt to achieve) with other software. This paper desribes those main functions of this software, with attention mainly focusing on its unique features and their performance in actual industrial case studies, including reconstruction along arbitrary orientation, multiple reconstructions of a scan, realignment of top views to a preferred direction, various measurements and so on. 5 Future Work The future works will focus on developing and implementing beam-hardening correction, 3D-stitching with multiple scans of the large planar object. [ID196] 8

9 Reference [1] T. Liu, "Direct Central Ray Determination in Micro-CT", Optical Engineering, vol. 48(NA), pp (2009) [2] T. Liu, "Differential Reconstruction for Planar Object in Computed Tomography", Journal of X- ray Science and Technology, vol. 17(2), pp (2009) [3] T. Liu, Cone-beam reconstruction for planar object, NDT & E International, vol. 45, pp (2012) [4] Liu Tong, Book Chapter: Differential Cone-Beam CT Reconstruction for Planar Objects, Computed Tomography - Special Applications, Luca Saba (Ed.), ISBN: , InTech, available from: (2011) [5] T. Liu, L. Sim, J. Xu, Targeted reconstruction with differential planar computed tomography, NDT & E International 43(2) (2010), [6] T. Liu and A. A. Malcolm, "Development of Reconstruction Software for CT reconstruction of Planar Object", 2nd Singapore International non-destructive testing conference & exhibition (SINCE2013), 19-Jul-2013 to 20-Jul-2013, Singapore [ID196] 9