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| Content Provider | IEEE Xplore Digital Library |
|---|---|
| Author | Gullberg, G.T. Zeng, G.L. |
| Copyright Year | 1963 |
| Abstract | 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.< |
| Sponsorship | IEEE Nuclear and Plasma Sciences Society Computer Applications in Nuclear and Plasma Sciences (CANPS) Lawrence Berkeley Lab. Lawrence Livermore Nat. Lab. APS College of William and Mary Continuous Electron Beam Accelerator Facility NASA Defence Nuclear Agency Sandia National Laboratories Jet Propulsion Laboratory Brookhaven Nat. Lab. Lawrence Livermore Nat. Lab IEEE/NPPS Radiat. Effects Committee Defence Nuclear Agency/DoD Sandia National Laboratories/DOE Jet Propulsion Laboratory/NASA Phillips Lab./DoD |
| Starting Page | 1257 |
| Ending Page | 1266 |
| Page Count | 10 |
| File Size | 843347 |
| File Format | |
| ISSN | 00189499 |
| Volume Number | 42 |
| Issue Number | 4 |
| Language | English |
| Publisher | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Publisher Date | 1995-08-01 |
| Publisher Place | U.S.A. |
| Access Restriction | One Nation One Subscription (ONOS) |
| Rights Holder | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Subject Keyword | Tomography Geometry Filtering algorithms Detectors Image reconstruction Computer simulation Focusing Pixel Fast Fourier transforms Filters |
| Content Type | Text |
| Resource Type | Article |
| Subject | Nuclear and High Energy Physics Electrical and Electronic Engineering Nuclear Energy and Engineering |
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