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Patent 4189775: Method and apparatus for subsection analysis using computed tomography (4748 words) |
 | projection data, are obtained from radiation beams penetrating the sectional portion of the subject in parallel therewith and in fixed directions of projection at varied angles, and then the projection data are filtered for the calculation of modified projection data. |
| The filtering operation is performed in order to remove fuzziness or blurring that may be caused if the image is constructed from the data back projected as they are. |
| According to the fundamental principles of the filtered-back projection method, the projection data g(X,.theta.) is transformed to the frequency domain by Fourier transformation multiplied by the filter function H(.omega.), transformation by inverse Fourier transform to calculate the modified projection data, the back-projected for reconstruction and display of an image of the sectional portion. |
| Single photon emission computed tomography - Wikipedia, the free encyclopedia (208 words) |
| Then a series of projection images are acquired using a gamma camera. |
| The projection images are stored digitally and a sophisticated computer program is used to process them and produce the slices (this is called reconstruction). |
| At the time of writing (2004), by far the most commonly used method is ' filtered back projection '. |
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