3D Spectroscopic computed tomography imaging using terahertz waves
28 Oct 2010-pp 1-2
TL;DR: In this paper, a three-dimensional spectroscopic imaging system that uses terahertz waves and is based on transmission computed tomography was developed, which is used for high refractive index objects with identification of chemical components.
Abstract: We have developed a three-dimensional spectroscopic imaging system that uses terahertz waves and is based on transmission computed tomography. Using this system, we demonstrate transmission three-dimensional computed tomography imaging of high refractive index objects, with identification of chemical components, by analyzing spectroscopic information.
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TL;DR: In this paper, the principles of tomography for terahertz Computed tomography (CT), tomosynthesis (TS), synthetic aperture radar (SAR), and time-of-flight (TOF) tomography are established.
Abstract: Terahertz and millimeter waves penetrate various dielectric materials, including plastics, ceramics, crystals, and concrete, allowing terahertz transmission and reflection images to be considered as a new imaging tool complementary to X-Ray or Infrared. Terahertz imaging is a well-established technique in various laboratory and industrial applications. However, these images are often two-dimensional. Three-dimensional, transmission-mode imaging is limited to thin samples, due to the absorption of the sample accumulated in the propagation direction. A tomographic imaging procedure can be used to acquire and to render three-dimensional images in the terahertz frequency range, as in the optical, infrared or X-ray regions of the electromagnetic spectrum. In this paper, after a brief introduction to two dimensional millimeter waves and terahertz imaging we establish the principles of tomography for Terahertz Computed tomography (CT), tomosynthesis (TS), synthetic aperture radar (SAR) and time-of-flight (TOF) terahertz tomography. For each technique, we present advantages, drawbacks and limitations for imaging the internal structure of an object.
215 citations
Cites methods from "3D Spectroscopic computed tomograph..."
...Coherent detection methods are used to allow the reflected or transmitted THz pulse profile to be measured [135]....
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TL;DR: Two-dimensional and three-dimensional analyses have been performed in order to reveal the internal structure of nearly 3500-year-old sealed Egyptian jars.
Abstract: A monochromatic millimeter-wave imaging system coupled with an infrared temperature sensor has been used to investigate historic objects preserved at the Museum of Aquitaine (France). In particular, two-dimensional and three-dimensional analyses have been performed in order to reveal the internal structure of nearly 3500-year-old sealed Egyptian jars.
39 citations
Cites background from "3D Spectroscopic computed tomograph..."
...simple manufactured phantom objects, such as foam or polyethylene cylinders, drilled with metallic bars [10,11] or filled with specific chemical substances such as lactose or lactose powder [12,13]....
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TL;DR: In this article, a 3D continuous-wave (CW) terahertz computed tomography (CT) system employing a gas laser operating at 2.52 THz is presented.
Abstract: A 3D continuous-wave (CW) terahertz computed tomography (CT) system employing a gas laser operating at 2.52 THz is presented. To shorten acquisition time on the premise of guaranteeing the image quality, the modified simultaneous algebraic reconstruction technique (MSART) coupled with image processing operations like the Gaussian low-pass filter (GLPF), open operation and close operation has been adopted in the paper. With the 2D results the 3D images of the samples have been also obtained. The reconstruction results illustrate the promising application prospects of this CW THz CT system.
20 citations
TL;DR: In this article, the 3D image of the sample is performed in the low absorption liquid, the refractive index of which is close to the sample, and the defect with different sizes inside the sample are measured with refractive matching method.
Abstract: Terahertz (THz) computed tomography (CT) is a promising technique to obtain the internal information of objects due to its properties of nonionizing and high penetration of nonpolar objects. However, THz CT is hindered by the strong refractive effect and Fresnel reflection loss when it is applied to high-refractive-index samples. In this paper, the three-dimensional image of the sample is performed in the low absorption liquid, the refractive index of which is close to the sample. This novel experimental procedure can eliminate the refractive effect and Fresnel reflection loss effectively. Together with the data processing to eliminate the liquid absorption and to restrain the artifacts, the THz CT imaging of high-density polyethylene ( n = 1.53) cylinders and cubes is achieved successfully. The internal hole and metallic foreign body are shown accurately. In addition, the defects with different sizes inside the sample are measured with refractive index matching method. It shows that THz CT imaging based on refractive index matching method has high sensitivity to detect the small defect inside the sample as small as 0.5 mm diameter.
10 citations
Cites background from "3D Spectroscopic computed tomograph..."
...In addition, THz wave has the broad spectral bandwidth, making the spectroscopic THz CT possible [12], [13]....
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TL;DR: Terahertz computed tomography makes use of the penetrability of terahertz radiation and obtains three-dimensional (3-D) object projection data in this paper.
Abstract: Terahertz computed tomography makes use of the penetrability of terahertz radiation and obtains three-dimensional (3-D) object projection data Continuous-wave terahertz digital holographic tomography with a pyroelectric array detector is presented Compared with scanning terahertz computed tomography, a pyroelectric array detector can obtain a large quantity of projection data in a short time To obtain a 3-D image, in-line digital holograms of the object are recorded from various directions and reconstructed to obtain two-dimensional (2-D) projection data; then 2-D cross-sectional images and 3-D images of the internal structure of the object are obtained by the filtered back projection algorithm The presented system can rapidly reconstruct the 3-D object and reveals the internal 3-D structure of the object A 3-D reconstruction of a polyethylene straw is presented with a 6% error in retrieved diameter
9 citations
References
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Book•
01 Jan 1987TL;DR: Properties of Computerized Tomographic Imaging provides a tutorial overview of topics in tomographic imaging covering mathematical principles and theory and how to apply the theory to problems in medical imaging and other fields.
Abstract: Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions. The impact of tomography in diagnostic medicine has been revolutionary, since it has enabled doctors to view internal organs with unprecedented precision and safety to the patient. There are also numerous nonmedical imaging applications which lend themselves to methods of computerized tomography, such as mapping of underground resources...cross-sectional imaging of for nondestructive testing...the determination of the brightness distribution over a celestial sphere...three-dimensional imaging with electron microscopy. Principles of Computerized Tomographic Imaging provides a tutorial overview of topics in tomographic imaging covering mathematical principles and theory...how to apply the theory to problems in medical imaging and other fields...several variations of tomography that are currently being researched.
5,620 citations
"3D Spectroscopic computed tomograph..." refers methods in this paper
...Conventional CT is based the Radon transform [5], and reconstruction of measured data typically is performed by filtered backprojection [ 6 ]....
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TL;DR: A novel basic technology for terahertz imaging is developed, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis.
Abstract: The absence of non-destructive inspection techniques for illicit drugs hidden in mail envelopes has resulted in such drugs being smuggled across international borders freely. We have developed a novel basic technology for terahertz imaging, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis. The spatial distributions of the targets are obtained from terahertz multispectral transillumination images, using absorption spectra measured with a tunable terahertz-wave source. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.
1,309 citations
"3D Spectroscopic computed tomograph..." refers methods in this paper
...Kawase et al. first demonstrated the identification of MDMA and MA by two-dimensional (2D) spectroscopic imaging using THz waves [ 1 ]....
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TL;DR: A tomographic imaging modality that uses pulsed terahertz (THz) radiation to probe the optical properties of three-dimensional structures in the far-infrared, analogous to conventional CT techniques such as x-ray CT.
Abstract: We demonstrate a tomographic imaging modality that uses pulsed terahertz (THz) radiation to probe the optical properties of three-dimensional (3D) structures in the far-infrared. This THz-wave computed tomography (T-ray CT) system provides sectional images of objects in a manner analogous to conventional CT techniques such as x-ray CT. The transmitted amplitude and phase of broadband pulses of THz radiation are measured at multiple projection angles. The filtered backprojection algorithm is then used to reconstruct the target object, including both its 3D structure and its frequency-dependent far-infrared optical properties.
322 citations
"3D Spectroscopic computed tomograph..." refers background in this paper
...One of the first examples of CT utilizing THz waves was reported by Ferguson et al. [ 4 ]....
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28 Oct 2010
TL;DR: The 3D Imaging Analysis System (3DIA) as mentioned in this paper uses terahertz waves for non-destructive analysis of the spatial distribution of constituents, which is the first such system for practical applications.
Abstract: We have developed the “3D Imaging Analysis System” that uses terahertz waves, the world's first such system for practical applications. This system has an unprecedented capability for nondestructive three-dimensional spectroscopic analysis of the spatial distribution of constituents.
9 citations
10 Nov 2009
TL;DR: In this paper, the authors performed 2D tomographic measurements upon shaped phantoms constructed from material with low optical power, using a time-domain THz arrangement, demonstrating distortions that may be a consequence of beam diffraction effect.
Abstract: We have performed 2-dimensional tomographic measurements upon shaped phantoms constructed from material with low optical power, using a time-domain THz arrangement. While the phantom morphology can be successfully reconstructed using the time-delay data, use of the THz pulse amplitude is less reliable, demonstrating distortions that may be a consequence of beam diffraction effect. This effectively masks the true attenuation contrast of the object.
1 citations