| 摘要 |
At least one embodiment of the present invention relates to a method for extrapolation of truncated, incomplete projections for computed tomography. At least one embodiment of the method is based on the use of CT units having multi-row detectors and scanning in spiral scan operation and includes at least the following. Firstly, scanning of an examination object with the aid of a beam. Secondly, detection of complete and incomplete projection data during a scan. Thirdly, the carrying out of a parallel rebinning for the detected projection data. Fourthly, determining incomplete, truncated projections based on analysis of the 3D signal path in the 3D sinogram belonging to each voxel in the object region. Fifthly, extrapolating the incomplete, truncated projections by continuing the terminated or discontinuous 3D signal paths according to <maths id="MATH-US-00001" num="00001"> <math overflow="scroll"> <mrow> <mrow> <mover> <mi>P</mi> <mo>^</mo> </mover> <mo></mo> <mrow> <mo>(</mo> <mrow> <mi>r</mi> <mo>,</mo> <mi>Phi</mi> <mo>,</mo> <mi>z</mi> </mrow> <mo>)</mo> </mrow> </mrow> <mo>=</mo> <mrow> <msub> <mi>min</mi> <mrow> <mo>(</mo> <mrow> <mi>t</mi> <mo>,</mo> <mi>theta</mi> </mrow> <mo>)</mo> </mrow> </msub> <mo></mo> <mrow> <mo>(</mo> <mrow> <mrow> <mrow> <msub> <mi>P</mi> <mi>theta</mi> </msub> <mo></mo> <mrow> <mo>(</mo> <mrow> <mrow> <mi>t</mi> <mo></mo> <mrow> <mo>(</mo> <mrow> <mi>r</mi> <mo>,</mo> <mi>theta</mi> <mo>,</mo> <mi>Phi</mi> </mrow> <mo>)</mo> </mrow> </mrow> <mo>,</mo> <mrow> <mi>q</mi> <mo></mo> <mrow> <mo>(</mo> <mrow> <mi>z</mi> <mo>,</mo> <mi>theta</mi> </mrow> <mo>)</mo> </mrow> </mrow> </mrow> <mo>)</mo> </mrow> </mrow> <mo>.</mo> <mrow> <msub> <mi>I</mi> <mi>theta</mi> </msub> <mo></mo> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow> </mrow> <mo>,</mo> <mstyle> <mtext> </mtext> </mstyle> <mo></mo> <mrow> <mrow> <mi>I</mi> <mo></mo> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow> <mo>=</mo> <mrow> <mo>{</mo> <mrow> <mtable> <mtr> <mtd> <mn>1</mn> </mtd> <mtd> <mrow> <mrow> <mrow> <mo>∀</mo> <mi>t</mi> </mrow> <mo>=</mo> <mrow> <mi>r</mi> <mo>.</mo> <mrow> <mi>cos</mi> <mo></mo> <mrow> <mo>(</mo> <mrow> <mi>theta</mi> <mo>+</mo> <mi>Phi</mi> </mrow> <mo>)</mo> </mrow> </mrow> </mrow> </mrow> <mo>,</mo> <mrow> <mi>q</mi> <mo>=</mo> <mrow> <mi>q</mi> <mo></mo> <mrow> <mo>(</mo> <mrow> <mi>theta</mi> <mo>,</mo> <mi>z</mi> </mrow> <mo>)</mo> </mrow> </mrow> </mrow> </mrow> </mtd> </mtr> <mtr> <mtd> <mn>0</mn> </mtd> <mtd> <mi>otherwise</mi> </mtd> </mtr> </mtable> <mo>.</mo> </mrow> </mrow> </mrow> </mrow> </mrow> </mrow> </mrow> </math> </maths>
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