The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Vasilis Ntziachristos - One of the best experts on this subject based on the ideXlab platform.
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in vivo imaging of murine tumors using complete Angle Projection fluorescence molecular tomography
Journal of Biomedical Optics, 2009Co-Authors: Vasilis Ntziachristos, Nikolaos C Deliolanis, Joshua Dunham, Thomas Wurdinger, Joseluiz Figueiredo, Bakhos A TannousAbstract:We interrogate the ability of free-space fluorescence tomography to image small animals in vivo using charge-coupled device (CCD) camera measurements over 360-deg noncontact Projections. We demonstrate the performance of normalized dual-wavelength measurements that are essential for in-vivo use, as they account for the heterogeneous distribution of photons in tissue. In-vivo imaging is then showcased on mouse lung and brain tumors cross-validated by x-ray microcomputed tomography and histology.
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complete Angle Projection diffuse fluorescence molecular tomography with early photons
Biosilico, 2006Co-Authors: Mark Niedre, Gordon M Turner, Vasilis NtziachristosAbstract:In this work we demonstrate diffuse fluorescence tomography using early transmitted photons and complete-Angle Projection. We describe instrumentation and reconstruction algorithms and show preliminary images of complex fluorescent phantoms and of mice with implanted fluorophores
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complete Angle Projection diffuse optical tomography by use of early photons
Optics Letters, 2005Co-Authors: Gordon M Turner, Giannis Zacharakis, Antoine Soubret, Jorge Ripoll, Vasilis NtziachristosAbstract:We present the first, to our knowledge, experimental images of complex-shaped phantoms embedded in diffuse media by use of optical tomography. Imaging is based on a complete-Angle Projection tomographic technique that utilizes transmitted early photons. Results are contrasted with measurements obtained at later gates as well as pseudocontinuous-wave data. The scanning system developed employs noncontact illumination and detection technologies that allow for high spatial sampling of transmitted photons. Combining this system with complete-Angle illumination is found to be an important strategy toward improved imaging performance, resulting in a better-posed inversion problem. The appropriateness of reconstruction algorithms similar to those employed in x-ray computed tomography are showcased, and suggestions for model improvements are provided.
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Early-photon tomographic imaging with 360-degree sample rotation
Biosilico, 2004Co-Authors: Gordon M Turner, Giannis Zacharakis, Jorge Ripoll, Vasilis NtziachristosAbstract:An early photon detection multi-Angle Projection, high spatial sampling system has been developed to fully exploit the advantages of time-resolved methods in imaging diffuse media and offer measurements of maximum information content.
Li Zeng - One of the best experts on this subject based on the ideXlab platform.
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Guided Image Filtering Based Limited-Angle CT Reconstruction Algorithm Using Wavelet Frame
IEEE Access, 2019Co-Authors: Jiaxi Wang, Chengxiang Wang, Wei Yu, Li ZengAbstract:Computed tomography (CT) has its irreplaceable function in nondestructive testing and medical diagnosis. In some practical CT imaging applications, the limited-Angle scanning is common due to X-ray's potential harm to human and the limitation of the scanning conditions. Under these circumstances, analytic reconstruction algorithms, like filtered backProjection (FBP), will not obtain satisfactory results because of lacking the Projection data. Iterative reconstruction (IR) methods that can incorporate prior knowledge have attracted attention in many fields, and wavelet frame-based regularization reconstruction algorithms have proven to be a useful means to reduce slope artifacts and noise for limited-Angle CT. However, with the obtained Projection data of the scanned object further reduces, the edge structures and the details of the reconstructed image worsen. For the sake of improving the quality of the reconstructed image from the limited-Angle Projection data, a guided image filtering (GIF)-based limited-Angle CT reconstruction algorithm using wavelet frame was proposed. In each iteration of the proposed algorithm, the reconstructed result constrained by the wavelet frame was used as the guidance image to transfer the important features it contains to the reconstructed result of SART method by GIF. Furthermore, some simulated experiments and real data tests were conducted to evaluate the feasibility and validity of the proposed algorithm, and the qualitative and quantitative indexes indicated that the proposed algorithm was superior to other iterative reconstruction algorithms in artifacts reduction, noise suppression, and structure preservation.
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Limited-Angle image reconstruction based on Mumford–Shah-like model and wavelet tight frames
Journal of Optics, 2018Co-Authors: Lingli Zhang, Li Zeng, Chengxiang WangAbstract:Restricted by the scanning environment and the radiation exposure of computed tomography (CT), the obtained Projection data are sometimes incomplete, which results in an ill-posed problem, such as a limited-Angle image reconstruction. In such circumstance, the commonly used analytic and iterative algorithms, such as filtered back-Projection and simultaneous algebraic reconstruction technique (SART), will not work well. Nowadays, a popular iterative image reconstruction algorithm ( $${\hbox {SART}}+{\hbox {TV}}$$ ) solving the optimization model based on the minimization of total variation (TV) of the image applies to the sparse-view reconstruction problem well; it is not effective on small limited-Angle reconstruction problem, especially in aspect of suppressing slope artifacts when the limited-Angle Projection views are severely reduced. In this work, we develop a reconstruction model based on the Mumford–Shah-like model and wavelet tight frames that applies to limited-Angle CT; and the corresponding iterative method is given. Numerical experiments and quantitative analysis demonstrate that our method outperforms SART and $${\hbox {SART}}+{\hbox {TV}}$$ in suppressing slope artifacts when the limited-Angle Projection views are severely decreased.
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Wavelet tight frame and prior image-based image reconstruction from limited-Angle Projection data
Inverse Problems and Imaging, 2017Co-Authors: Chengxiang Wang, Li Zeng, Lingli ZhangAbstract:The limited-Angle Projection data of an object, in some practical applications of computed tomography (CT), are obtained due to the restriction of scanning condition. In these situations, since the Projection data are incomplete, some limited-Angle artifacts will be presented near the edges of reconstructed image using some classical reconstruction algorithms, such as filtered backProjection (FBP). The reconstructed image can be fine approximated by sparse coefficients under a proper wavelet tight frame, and the quality of reconstructed image can be improved by an available prior image. To deal with limited-Angle CT reconstruction problem, we propose a minimization model that is based on wavelet tight frame and a prior image, and perform this minimization problem efficiently by iteratively minimizing separately. Moreover, we show that each bounded sequence, which is generated by our method, converges to a critical or a stationary point. The experimental results indicate that our algorithm can efficiently suppress artifacts and noise and preserve the edges of reconstructed image, what's more, the introduced prior image will not miss the important information that is not included in the prior image.
Chengxiang Wang - One of the best experts on this subject based on the ideXlab platform.
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Guided Image Filtering Based Limited-Angle CT Reconstruction Algorithm Using Wavelet Frame
IEEE Access, 2019Co-Authors: Jiaxi Wang, Chengxiang Wang, Wei Yu, Li ZengAbstract:Computed tomography (CT) has its irreplaceable function in nondestructive testing and medical diagnosis. In some practical CT imaging applications, the limited-Angle scanning is common due to X-ray's potential harm to human and the limitation of the scanning conditions. Under these circumstances, analytic reconstruction algorithms, like filtered backProjection (FBP), will not obtain satisfactory results because of lacking the Projection data. Iterative reconstruction (IR) methods that can incorporate prior knowledge have attracted attention in many fields, and wavelet frame-based regularization reconstruction algorithms have proven to be a useful means to reduce slope artifacts and noise for limited-Angle CT. However, with the obtained Projection data of the scanned object further reduces, the edge structures and the details of the reconstructed image worsen. For the sake of improving the quality of the reconstructed image from the limited-Angle Projection data, a guided image filtering (GIF)-based limited-Angle CT reconstruction algorithm using wavelet frame was proposed. In each iteration of the proposed algorithm, the reconstructed result constrained by the wavelet frame was used as the guidance image to transfer the important features it contains to the reconstructed result of SART method by GIF. Furthermore, some simulated experiments and real data tests were conducted to evaluate the feasibility and validity of the proposed algorithm, and the qualitative and quantitative indexes indicated that the proposed algorithm was superior to other iterative reconstruction algorithms in artifacts reduction, noise suppression, and structure preservation.
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Limited-Angle image reconstruction based on Mumford–Shah-like model and wavelet tight frames
Journal of Optics, 2018Co-Authors: Lingli Zhang, Li Zeng, Chengxiang WangAbstract:Restricted by the scanning environment and the radiation exposure of computed tomography (CT), the obtained Projection data are sometimes incomplete, which results in an ill-posed problem, such as a limited-Angle image reconstruction. In such circumstance, the commonly used analytic and iterative algorithms, such as filtered back-Projection and simultaneous algebraic reconstruction technique (SART), will not work well. Nowadays, a popular iterative image reconstruction algorithm ( $${\hbox {SART}}+{\hbox {TV}}$$ ) solving the optimization model based on the minimization of total variation (TV) of the image applies to the sparse-view reconstruction problem well; it is not effective on small limited-Angle reconstruction problem, especially in aspect of suppressing slope artifacts when the limited-Angle Projection views are severely reduced. In this work, we develop a reconstruction model based on the Mumford–Shah-like model and wavelet tight frames that applies to limited-Angle CT; and the corresponding iterative method is given. Numerical experiments and quantitative analysis demonstrate that our method outperforms SART and $${\hbox {SART}}+{\hbox {TV}}$$ in suppressing slope artifacts when the limited-Angle Projection views are severely decreased.
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Wavelet tight frame and prior image-based image reconstruction from limited-Angle Projection data
Inverse Problems and Imaging, 2017Co-Authors: Chengxiang Wang, Li Zeng, Lingli ZhangAbstract:The limited-Angle Projection data of an object, in some practical applications of computed tomography (CT), are obtained due to the restriction of scanning condition. In these situations, since the Projection data are incomplete, some limited-Angle artifacts will be presented near the edges of reconstructed image using some classical reconstruction algorithms, such as filtered backProjection (FBP). The reconstructed image can be fine approximated by sparse coefficients under a proper wavelet tight frame, and the quality of reconstructed image can be improved by an available prior image. To deal with limited-Angle CT reconstruction problem, we propose a minimization model that is based on wavelet tight frame and a prior image, and perform this minimization problem efficiently by iteratively minimizing separately. Moreover, we show that each bounded sequence, which is generated by our method, converges to a critical or a stationary point. The experimental results indicate that our algorithm can efficiently suppress artifacts and noise and preserve the edges of reconstructed image, what's more, the introduced prior image will not miss the important information that is not included in the prior image.
Muneharu Kuwata - One of the best experts on this subject based on the ideXlab platform.
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a 65 in slim 255 mm depth laser tv with wide Angle Projection optical system
Journal of The Society for Information Display, 2009Co-Authors: Muneharu Kuwata, Hiroaki Sugiura, Tomohiro Sasagawa, Atsushi Michimori, Eiich Toide, Takayuki Yanagisawa, Syuhei Yamamoto, Yoshihito Hirano, Masahiro Usui, Shigenori TeramatsuAbstract:— A high-definition laser TV that employs a newly developed laser light source and a super-wide-Angle Projection optical system has been developed. This adoption of a laser light source with three primary colors helped to achieve an extremely wide color gamut, and, in addition, a compact optical engine, which has been optimized to the laser light source and contributed to the achievement of the stylish design of a large screen of 65 in., with the depth being only 255 mm.
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A 65‐in. slim (255‐mm depth) laser TV with wide‐Angle Projection optical system
Journal of The Society for Information Display, 2009Co-Authors: Muneharu Kuwata, Hiroaki Sugiura, Tomohiro Sasagawa, Atsushi Michimori, Eiich Toide, Takayuki Yanagisawa, Syuhei Yamamoto, Yoshihito Hirano, Masahiro Usui, Shigenori TeramatsuAbstract:— A high-definition laser TV that employs a newly developed laser light source and a super-wide-Angle Projection optical system has been developed. This adoption of a laser light source with three primary colors helped to achieve an extremely wide color gamut, and, in addition, a compact optical engine, which has been optimized to the laser light source and contributed to the achievement of the stylish design of a large screen of 65 in., with the depth being only 255 mm.
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70.3: Distinguished Contributed Paper: Wide Angle Projection Optics for Compact Rear Projector
SID Symposium Digest of Technical Papers, 2005Co-Authors: Muneharu Kuwata, Tomohiro Sasagawa, Kuniko Kojima, Junichi Aizawa, Akihisa Miyata, Shinsuke Shikama, Hiroshi SuzukiAbstract:We have developed a new Projection optics with the exceptionally wide field Angle of 160 degrees and the short Projection distance of 125 mm with a 62 inch screen. It is constructed based on the Direct Projection Method which does not need a back mirror. In this paper, we will describe our new optical design concept and the characteristics of a prototype optical system.
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70.1: Invited Paper: Ultra‐Thin Rear Projector
SID Symposium Digest of Technical Papers, 2005Co-Authors: Shinsuke Shikama, Muneharu Kuwata, Hiroshi Suzuki, Takao Endo, Tomohiro SasagawaAbstract:Three years ago, an ultra-thin rear projector attracted people's eyes only for the great thickness reduction. But today, in the situation where some new models had been presented, ultra-thin rear projectors are making their own position in FPD market. In this paper, we describe the latest trend of the ultra-thin rear projectors in FPD market, and review the wide-Angle Projection optics ever reported. And we also discuss key issues for further improvement of the Projection optics.
Ge Wang - One of the best experts on this subject based on the ideXlab platform.
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exact interior reconstruction from truncated limited Angle Projection data
International Journal of Biomedical Imaging, 2008Co-Authors: Yangbo Ye, Hengyong Yu, Ge WangAbstract:Using filtered backProjection (FBP) and an analytic continuation approach, we prove that exact interior reconstruction is possible and unique from truncated limited-Angle Projection data, if we assume a prior knowledge on a subregion or subvolume within an object to be reconstructed. Our results show that (i) the interior region-of-interest (ROI) problem and interior volume-ofinterest (VOI) problem can be exactly reconstructed from a limited-Angle scan of the ROI/VOI and a 180 degree PI-scan of the subregion or subvolume and (ii) the whole object function can be exactly reconstructed from nontruncated Projections from a limited-Angle scan. These results improve the classical theory of Hamaker et al. (1980).
