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Experimental investigation of arbitrary-orientation cone-beam X-ray tomography
(2007-01-01)
Chanwimalueang, T.
;
Sangworasil, M.
;
Pintavirooj, C.
X-ray Computed Tomography is a technique to reconstruct an image of trans-axial slab of the object from a series of x-ray radiographs taken at a prior-known angle. Sequences of x-ray radiographs are served as two-dimensional projection data for a 3D tomography. The most popular Feldkamp Algorithm which is based on Filtered Backprojection (FBP) approaches has shown to perform well for 3D reconstruction. In the case of limited view, however, Feldkamp Algorithm suffers from star artifact. In these scenarios, an algebraic reconstruction technique such as the Simultaneous Algebraic Reconstruction Technique (SART) is engaged for reconstructing tomograms. Conventional x-ray computed tomography was implemented on a c-arm x-ray apparatus where the x-ray source and detector is capable of rotating to capture radiograph at any specific angle. The implementation of conebeam - geometry reconstruction algorithm, however, requires that the center location of the detector is accurately identified. Any slightly-missed alignment of the x-ray source or the detector could result in the error of the position of the center and hence the error in reconstructed image. Consequently, x-ray radiography tomography is normally implemented on a c-arm x-ray apparatus where the correct orientation of x-ray tube with respect to x-ray detector is achievable. The aim of this paper is to implement the x-ray tomography on a non c-arm x-ray apparatus where the x-ray source can be in any orientation with respect to x-ray detector. To determine the orientation, we take the radiograph of the reference transparent object, say the plastic box, of which the coordinate of the landmark, say the corner point, is known. The shadowgram of the box is analyzed to extract the coordinate of landmark image and to determine the orientation matrix using classical direct linear transform method (DLT). Once the orientation is known, modified conebeam tomography is performed to derived 3D reconstruction volumetric data. The experimental results demonstrated the potential of such method.
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3D modeling from multiple projections with arbitrary-posed camera
(2006-12-01)
Gimjumpa, S.
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Narkbuekaew, W.
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Sangworasil, M.
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Pintavirooj, C.
Tomographic imaging is a technique for exploration of a cross-section of an inspected object without destruction. In this research, the series of photographs taken around the opaque object under the ambient light is completely served as the projections- the so-called photo-graphic tomography. From the process of tomography, the outcome is the stack of pseudo cross-sectional image. Not the internal of cross section is authentic, but the edge or contour is valid. In this paper, the concept for 3D modeling using photographic tomography was extended to the case where the camera pose can be varied arbitrary. In such case, camera pose is determined using general camera modeling technique. The extracted geometric transform matrix is used to reorient reconstructed data before implementing the traditional tomographic process. The simulation result is very promising. © 2006 IEEE.
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3D modeling from multiple projections: Parallel-beam to helical cone-beam trajectory
(2005-12-01)
Narkbuakaew, W.
;
Pintavirooj, C.
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Withayachumnankul, W.
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Sangworasil, M.
;
Taertulakarn, S.
Tomographic imaging is a technique for exploration of a cross-section of an inspected object without destruction. Normally, the input data, known as the projections, are gathered by repeatedly radiating coherent waveform through the object in a number of viewpoints, and receiving by an array of corresponding detector in the opposite position. In this research, as a replacement of radiographs, the series of photographs taken around the opaque object under the ambient light is completely served as the projections. The purposed technique can be adopted with various beam geometry including parallel-beam, cone-beam and spiral cone-beam geometry. From the process of tomography, the outcome is the stack of pseudo cross-sectional image. Not the internal of cross section is authentic, but the edge or contour is valid. Copyright UNION Agency - Science Press.
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3D modeling from using spiral cone-beam trajectory
(2005-01-01)
Narkbuakaew, W.
;
Withayachumnankul, W.
;
Pintavirooj, C.
;
Sangworasil, M.
Tomographic imaging is a technique for exploration of a cross-section of an inspected object without destruction. Normally, the input data, known as the projections, are gathered by repeatedly radiating coherent waveform through the object in a number of viewpoints, and receiving by an array of corresponding detector in the opposite position. In this research, as a replacement of radiographs, the series of photographs taken around the opaque object under the ambient light is completely served as the projections. The process is called photographic tomograph. In this paper, we purpose the 3D shape extraction based on using photographic tomography with spiral cone-beam trajectory. We have demonstrated that the purposed technique can rectify the problem of perspective occlusion that occurs when using cone-beam trajectory.

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