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Gengsheng L. Zeng - One of the best experts on this subject based on the ideXlab platform.
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List-mode data reconstruction via the finite Hilbert transform of the derivative of the Backprojection
2007 IEEE Nuclear Science Symposium Conference Record, 2007Co-Authors: Gengsheng L. ZengAbstract:An exact analytical image reconstruction method is presented for two-dimensional (2D) imaging. The method performs Backprojection, the derivative and finite Hilbert transforms. This method can be applied to many imaging geometries. The Backprojection procedure is imaging- geometry dependent, while the differentiation and the finite Hilbert transform procedures are identical for all imaging geometries. This algorithm is applicable to list-mode data in nuclear medicine, while other filtered Backprojection algorithms cannot be applied directly to the list-mode data.
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Image reconstruction via the finite Hilbert transform of the derivative of the Backprojection.
Medical Physics, 2007Co-Authors: Gengsheng L. ZengAbstract:An exact analytical image reconstruction method is presented for two-dimensional imaging. The method performs Backprojection, the derivative and finite Hilbert transforms. This method can be applied to many imaging geometries. The Backprojection procedure is imaging-geometry dependent, while the differentiation and the finite Hilbert transform procedures are identical for all imaging geometries. This algorithm is applicable to list-mode data in nuclear medicine, while other filtered Backprojection algorithms cannot be applied directly to the list-mode data.
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Backprojection filtering for variable orbit fan-beam tomography
IEEE Transactions on Nuclear Science, 1995Co-Authors: Grant T. Gullberg, Gengsheng L. ZengAbstract:Backprojection filtering algorithms are presented for three variable orbit fan-beam geometries. Expressions for the fan-beam projection and Backprojection operators are given for a flat detector fan-beam geometry with fixed focal length, with variable focal length, and with fixed focal length and off-center focusing. Backprojection operators are derived for each geometry using transformation of coordinates to transform from a parallel geometry backprojector to a fan-beam backprojector for the appropriate geometry. The Backprojection operator includes a factor which is a function of the coordinates of the projection ray and the coordinates of the pixel in the backprojected image. The Backprojection filtering algorithm first backprojects the variable orbit fan-beam projection data using the appropriately derived backprojector to obtain a 1/r blurring of the original image, then takes the two-dimensional (2D) Fast Fourier Transform (FFT) of the backprojected image, then multiples the transformed image by the 2D ramp filter function, and finally takes the inverse 2D FFT to obtain the reconstructed image. Computer simulations verify that backprojectors with appropriate weighting give artifact free reconstructions of simulated line integral projections. Also, it is shown that it is not necessary to assume a projection model of line integrals, but the projector and backprojector can be defined to model the physics of the imaging detection process. A backprojector for variable orbit fan-beam tomography with fixed focal length is derived which includes an additional factor which is a function of the flux density along the flat detector. It is shown that the impulse response for the composite of the projection and Backprojection operations is equal to 1/r. >
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Backprojection filtering for variable orbit fan beam tomography
Proceedings of 1994 IEEE Nuclear Science Symposium - NSS'94, 1994Co-Authors: Grant T. Gullberg, Gengsheng L. ZengAbstract:A Backprojection filtering algorithm is presented for variable orbit fan-beam tomography. Expressions for the fan beam projection and Backprojection operators are given for a fan-beam geometry with flat detector. The Backprojection operator is derived such that the impulse response for the composite of the projection and Backprojection operations is equal to l/r if the data are acquired over 360 degrees. The algorithm first backprojects the variable orbit fan-beam projection data using the newly derived backprojector, takes the two-dimensional (2D) Fast Fourier Transform (FFT) of the backprojected image, multiplies the transformed image by the 2D ramp filter function, and finally takes the inverse 2D FFT to obtain the reconstructed image. The Backprojection operator includes a factor which is a function of the flux density along the flat detector which is a function of the rate of change of the orbit radius as a function of angle. The algorithm is verified using computer simulations. >
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A study of reconstruction artifacts in cone beam tomography using filtered Backprojection and iterative EM algorithms
IEEE Transactions on Nuclear Science, 1990Co-Authors: Gengsheng L. Zeng, Grant T. GullbergAbstract:Reconstruction artifacts in cone beam tomography are studied for filtered Backprojection (Feldkamp) and iterative EM algorithms. The filtered Backprojection algorithm uses a voxel-driven, interpolated Backprojection to reconstruct the cone beam data, whereas the iterative EM algorithm performs ray-driven projection and Backprojection operations for each iteration. Two weighting schemes for the projection and Backprojection operations in the EM algorithm are studied. One weights each voxel by the length of the ray through the voxel and the other equates the value of a voxel to the functional value of the midpoint of the line intersecting the voxel, which is obtained by interpolating between eight neighboring voxels. Cone beam reconstruction artifacts such as rings, bright vertical extremities, and slice-to-slice cross-talk are not found with parallel beam and fan beam geometries. When using filtered Backprojection and iterative EM algorithms, the line-length weighting is susceptible to ring artifacts which are improved by using interpolated projector-backprojectors. >
Grant T. Gullberg - One of the best experts on this subject based on the ideXlab platform.
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Backprojection filtering for variable orbit fan-beam tomography
IEEE Transactions on Nuclear Science, 1995Co-Authors: Grant T. Gullberg, Gengsheng L. ZengAbstract:Backprojection filtering algorithms are presented for three variable orbit fan-beam geometries. Expressions for the fan-beam projection and Backprojection operators are given for a flat detector fan-beam geometry with fixed focal length, with variable focal length, and with fixed focal length and off-center focusing. Backprojection operators are derived for each geometry using transformation of coordinates to transform from a parallel geometry backprojector to a fan-beam backprojector for the appropriate geometry. The Backprojection operator includes a factor which is a function of the coordinates of the projection ray and the coordinates of the pixel in the backprojected image. The Backprojection filtering algorithm first backprojects the variable orbit fan-beam projection data using the appropriately derived backprojector to obtain a 1/r blurring of the original image, then takes the two-dimensional (2D) Fast Fourier Transform (FFT) of the backprojected image, then multiples the transformed image by the 2D ramp filter function, and finally takes the inverse 2D FFT to obtain the reconstructed image. Computer simulations verify that backprojectors with appropriate weighting give artifact free reconstructions of simulated line integral projections. Also, it is shown that it is not necessary to assume a projection model of line integrals, but the projector and backprojector can be defined to model the physics of the imaging detection process. A backprojector for variable orbit fan-beam tomography with fixed focal length is derived which includes an additional factor which is a function of the flux density along the flat detector. It is shown that the impulse response for the composite of the projection and Backprojection operations is equal to 1/r. >
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Backprojection filtering for variable orbit fan beam tomography
Proceedings of 1994 IEEE Nuclear Science Symposium - NSS'94, 1994Co-Authors: Grant T. Gullberg, Gengsheng L. ZengAbstract:A Backprojection filtering algorithm is presented for variable orbit fan-beam tomography. Expressions for the fan beam projection and Backprojection operators are given for a fan-beam geometry with flat detector. The Backprojection operator is derived such that the impulse response for the composite of the projection and Backprojection operations is equal to l/r if the data are acquired over 360 degrees. The algorithm first backprojects the variable orbit fan-beam projection data using the newly derived backprojector, takes the two-dimensional (2D) Fast Fourier Transform (FFT) of the backprojected image, multiplies the transformed image by the 2D ramp filter function, and finally takes the inverse 2D FFT to obtain the reconstructed image. The Backprojection operator includes a factor which is a function of the flux density along the flat detector which is a function of the rate of change of the orbit radius as a function of angle. The algorithm is verified using computer simulations. >
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A study of reconstruction artifacts in cone beam tomography using filtered Backprojection and iterative EM algorithms
IEEE Transactions on Nuclear Science, 1990Co-Authors: Gengsheng L. Zeng, Grant T. GullbergAbstract:Reconstruction artifacts in cone beam tomography are studied for filtered Backprojection (Feldkamp) and iterative EM algorithms. The filtered Backprojection algorithm uses a voxel-driven, interpolated Backprojection to reconstruct the cone beam data, whereas the iterative EM algorithm performs ray-driven projection and Backprojection operations for each iteration. Two weighting schemes for the projection and Backprojection operations in the EM algorithm are studied. One weights each voxel by the length of the ray through the voxel and the other equates the value of a voxel to the functional value of the midpoint of the line intersecting the voxel, which is obtained by interpolating between eight neighboring voxels. Cone beam reconstruction artifacts such as rings, bright vertical extremities, and slice-to-slice cross-talk are not found with parallel beam and fan beam geometries. When using filtered Backprojection and iterative EM algorithms, the line-length weighting is susceptible to ring artifacts which are improved by using interpolated projector-backprojectors. >
Michel Desvignes - One of the best experts on this subject based on the ideXlab platform.
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Algorithm Architecture Adequacy for High Speed 3D Tomography
2007Co-Authors: Nicolas Gac, Stéphane Mancini, Michel Desvignes, Dominique HouzetAbstract:Backprojection is a computational costly step in tomography image reconstruction such as Positron Emission Tomography (PET). In this purpose, this paper presents a Pipelined, Prefetch and Parallelized Architecture for PET Backprojection (3PA-PET). The main strength of this architecture comes from its original memory access strategy, masking the high memory latency of the external memory. The 3PAPET architecture is implemented on a System on Programmable Chip (SopC). Time performances are compared with a desktop PC, a workstation and a GPU. We prove that the exploitation of the intrinsic temporal and spatial locality by the 3D Predictive and Adaptative (3D-AP) memory cache succeeds to run efficiently several pipelines of Backprojection : each reaches a computational throughput close to 1 operation per cycle.
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SAC - Hardware/software 2D-3D Backprojection on a SoPC platform
Proceedings of the 2006 ACM symposium on Applied computing - SAC '06, 2006Co-Authors: Nicolas Gac, Stéphane Mancini, Michel DesvignesAbstract:The reduction of image reconstruction time is needed to spread the use of PET for research and routine clinical practice. In this purpose, this article presents a hardware/software architecture for the acceleration of 3D Backprojection based upon an efficient 2D Backprojection. This architecture has been designed in order to provide a high level of parallelism thanks to an efficient management of the memory accesses which would have been otherwise strongly slowed by the external memory. The reconstruction system is embedded in a SoPC platform (System on Programmable Chip), the new generation of reconfigurable circuit. The originality of this architecture comes from the design of a 2D Adaptative and Predictive Cache (2D-AP Cache) which has proved to be an efficient way to overcome the memory access bottleneck. Thanks to a hierarchical use of this cache, several Backprojection operators can run in parallel, accelerating in this manner noteworthy the reconstruction process. This 2D reconstruction system will next be used to speed up 3D image reconstruction.
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Hardware/software 2D-3D Backprojection on a SoPC platform
2006Co-Authors: Nicolas Gac, Stéphane Mancini, Michel DesvignesAbstract:The reduction of image reconstruction time is needed to spread the use of PET for research and routine clinical practice. In this purpose, this article presents a hardware/software architecture for the acceleration of 3D Backprojection based upon an efficient 2D Backprojection. This architecture has been designed in order to provide a high level of parallelism thanks to an efficient management of the memory accesses which would have been otherwise strongly slowed by the external memory. The reconstruction system is embedded in a SoPC platform (System on Programmable Chip), the new generation of reconfigurable circuit. The originality of this architecture comes from the design of a 2D Adaptative and Predictive Cache (2D-AP Cache) which has proved to be an efficient way to overcome the memory access bottleneck. Thanks to a hierarchical use of this cache, several Backprojection operators can run in parallel, accelerating in this manner noteworthy the reconstruction process. This 2D reconstruction system will next be used to speed up 3D image reconstruction.
H Rendon - One of the best experts on this subject based on the ideXlab platform.
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high resolution Backprojection at regional distance application to the haiti m7 0 earthquake and comparisons with finite source studies
Journal of Geophysical Research, 2012Co-Authors: Lingsen Meng, Jeanpaul Ampuero, A Sladen, H RendonAbstract:A catastrophic M_w7 earthquake ruptured on 12 January 2010 on a complex fault system near Port-au-Prince, Haiti. Offshore rupture is suggested by aftershock locations and marine geophysics studies, but its extent remains difficult to define using geodetic and teleseismic observations. Here we perform the multitaper multiple signal classification (MUSIC) analysis, a high-resolution array technique, at regional distance with recordings from the Venezuela National Seismic Network to resolve high-frequency (about 0.4 Hz) aspects of the earthquake process. Our results indicate westward rupture with two subevents, roughly 35 km apart. In comparison, a lower-frequency finite source inversion with fault geometry based on new geologic and aftershock data shows two slip patches with centroids 21 km apart. Apparent source time functions from USArray further constrain the intersubevent time delay, implying a rupture speed of 3.3 km/s. The tips of the slip zones coincide with subevents imaged by Backprojections. The different subevent locations found by Backprojection and source inversion suggest spatial complementarity between high- and low-frequency source radiation consistent with high-frequency radiation originating from rupture arrest phases at the edges of main slip areas. The centroid moment tensor (CMT) solution and a geodetic-only inversion have similar moment, indicating most of the moment released is captured by geodetic observations and no additional rupture is required beyond where it is imaged in our preferred model. Our results demonstrate the contribution of Backprojections of regional seismic array data for earthquakes down to M ≈ 7, especially when incomplete coverage of seismic and geodetic data implies large uncertainties in source inversions.
Hua Guo - One of the best experts on this subject based on the ideXlab platform.
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limited view photoacoustic imaging based on linear array detection and filtered mean Backprojection iterative reconstruction
Journal of Applied Physics, 2009Co-Authors: Sihua Yang, Hua GuoAbstract:Most existing photoacoustic tomography techniques require collecting complete projection data that are acquired on a defined circle surrounding the object. However, in clinical application, the object can only be approached from a limited angle mostly. Furthermore, with the incomplete projection data acquired in limited view, the general filtered Backprojection algorithm will streak image artifacts nearby the reconstructed location of absorbers. In this paper, we present a limited-view-scanning photoacoustic imaging system with a linear transducer array and develop a filtered mean-Backprojection-iteration (FMBPI) algorithm to reconstruct the absorbed optical deposit distribution. The FMBPI algorithm combines the terseness of the filtered Backprojection algorithm with the accuracy of the iterative reconstruction algorithm. Numerical simulation and experimental results validate that the algorithm can effectively reconstruct high-quality image with limited-view data. It is also demonstrated that with the FMB...