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Small-sized computed tomography system with rotating gantry
(2010-07-30)
Jantanayingyong, V.
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Chanwimalueang, T.
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Srisuk, N.
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Pintavirooj, C.
Small-sized computed tomography system with rotating gantry is presented in this paper. System calibration was performed before achieving the projection data. An object placed on platform was exposed by the x-ray every two degrees of rotating angle. Thus, 180 projection data were performed in this study. Finally, Feldkamp algorithm based on a 3D filtered backprojeciton was employed to reconstruct cross sectional images. The result shows that cross sectional images obtained from small-sized computed tomography were satisfactory. In conclusion, the small-sized computed tomography presented in this study is capable to construct the cross sectional images. Moreover, 3D model reconstructed from these cross sectional images will be performed in the future work.
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Robotic arm controller using muscular contraction classification based on independent component analysis
(2008-10-06)
Chanwimalueang, T.
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Sueaseenak, D.
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Laoopugsin, N.
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Pintavirooj, C.
We develop a multi-channel electromyogram acquisition system base on the Programmable System On Chip (PSOC) microcontroller to control Robotic Arm. The array of 4 × 4 surface electrodes which invents from the low-cost EKG electrodes is used as the input sensor. B-spline interpolation technique has been utilized to map the EMG signal on the muscle surface. The topological mapping of the EMG is then analyzed to classify the pattern of muscle contraction. The proposed system was successfully demonstrated to record EMG data and its surface mapping. The muscular-contraction classification of mapping is then applied using independent component analysis. The classification result is then applied to control the movement of the robotic arm. © 2008 IEEE.
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Independent component analysis: An application for muscular contraction classification
(2007-12-01)
Daochai, S.
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Sueaseenak, D.
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Chanwimalueang, T.
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Laoopugsin, N.
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Pintavirooj, C.
We develop a multi-channel electromyogram acquisition system using PSOC microcontroller to aquire multichannel EMG signals. An array of 4 x 4 surface electrodes is used to record the EMG signal. B-spline interpolation technique has been utilized to map the EMG signal on the muscle surface. The topological mapping of the EMG is then analyzed to classify the pattern of muscle contraction. The proposed system was successfully demonstrated to record EMG data and its surface mapping. The muscular contraction classification of mapping using independent component analysis demonstrates promising results. ©2007 IEEE.
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Bone mineral density and bone mineral content estimation using low-cost x-ray detector
(2007-12-01)
Chuaychunu, N.
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Pititheerapab, Y.
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Chanwimalueang, T.
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Lertprasert, P.
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Pintavirooj, C.
This paper presented a design of a low-cost x-ray-detector using CMOS camera with an application on bone mineral content estimation. The main components consist of CMOS camera, optical lens, and image intensifier screen. CMOS camera offers various advantages including miniature-sized, low power consumption and cost effective. To apply the CMOS camera as x-ray detector, x-ray-to-visible light convector is required. Our key component of x-ray-to-visible light converter is intensifier screen. The application of x-ray detector for bone mineral density (BMD) and bone mineral content (BMC) is also given in this paper. The concept of dual energy x-ray is adopted to estimate the BMD on the finger bone. To compute BMC from BMD, the area of the bone is required. The concept of aative contour is applied to estimate the finger-bone area. ©2007 IEEE.
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Experimental investigation of arbitrary-orientation cone-beam X-ray tomography
(2007-01-01)
Chanwimalueang, T.
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Sangworasil, M.
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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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Miniatured computed tomography system and calibration
(2006-12-01)
Pititheerapab, Y.
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Chanwimalueang, T.
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Pintavirooj, C.
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Tosranon, P.
In this paper, we focus on a miniature computed tomographic system with application in 3D modelling of bony structure of a small animal. Our system consists of an x-ray source, a rotating platform and an x-ray array detector unit. The rotating platform is controlled by a personal computer which can rotate the sitting object to arbitrary angle. The x-ray array detector is used to capture the 2D x-ray signal that traversing the object placed on the platform. The x-ray detector is an image intensifier tube of which the 2D image is coupled to the computer via a CCD camera. Feldkamp Conebeam technique is engaged for reconstructing tomograms due to its simplicity. Volume rendering technique together with the shading effects is performed on a stack of cross-sectional image to realize the data into 3D visualization. The algorithms are applied to the practical situation where a series of x-ray radiographs of an animal's bone are collected from the system. The 3D modelling of such bone is performed on the cross-sectional images reconstructed with Feldkamp Conebeam. The results are very satisfactory. © 2006 IEEE.
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Cone-beam X-ray tomography with arbitrary-orientation X-ray tube
(2006-12-01)
Sueseenak, D.
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Chanwimalueang, T.
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Narkbuekaew, W.
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Chitsakul, K.
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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 priorknown 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. Conventional x-ray computed tomography was implemented on a c-arm x-ray apparatus where the x-ray tube and detector is capable of rotating to capture radiograph at any specific angle. In this paper, the concept of x-ray computed tomography for non c-arm x-ray apparatus was presented. In the purposed method, the cross-section of the object can be reconstructed from the multiple-viewed radiographs taken with arbitrary orientation of x-ray tube. The simulation results demonstrated the potential of such method. © 2006 IEEE.
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Improved-resolution x-ray array detector applied for SART fanbeam
(2006-12-01)
Angsuwatanakul, T.
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Chanwimalueang, T.
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Pintavirooj, C.
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Sangworasil, M.
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Lertprasert, P.
In this paper, we investigate the design and construction of improved-resolution x-ray detector. Our detector is an array of photo-transistors coated with gadolinium based phosphor similar that used in the x-ray cassettes and used in advanced medical CT detector. The x-ray array detector module consists of two main part: the detector frontend and data acquisition system. The detector frontend includes preamplifying, low-pass filter. The data acquisition system is served to convert the signal in to digital form and forward it to personnel computer. The application of the detector as a CT detector shows a promising result. © 2006 IEEE.

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