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Article Dans Une Revue Medical Physics Année : 2016

Filtered-backprojection reconstruction for a cone-beam computed tomography scanner with independent source and detector rotations

Résumé

Purpose: A new cone-beam CT scanner for image-guided radiotherapy (IGRT) can independently rotate the source and the detector along circular trajectories. Existing reconstruction algorithms are not suitable for this scanning geometry. The authors propose and evaluate a three-dimensional (3D) filtered-backprojection reconstruction for this situation. Methods: The source and the detector trajectories are tuned to image a field-of-view (FOV) that is offset with respect to the center-of-rotation. The new reconstruction formula is derived from the Feldkamp algorithm and results in a similar three-step algorithm: projection weighting, ramp filtering, and weighted backprojection. Simulations of a Shepp Logan digital phantom were used to evaluate the new algorithm with a 10 cm-offset FOV. A real cone-beam CTimage with an 8.5 cm-offset FOV was also obtained from projections of an anthropomorphic head phantom. Results: The quality of the cone-beam CT images reconstructed using the new algorithm was similar to those using the Feldkamp algorithm which is used in conventional cone-beam CT. The real image of the head phantom exhibited comparable image quality to that of existing systems. Conclusions: The authors have proposed a 3D filtered-backprojection reconstruction for scanners with independent source and detector rotations that is practical and effective. This algorithm forms the basis for exploiting the scanner’s unique capabilities in IGRT protocols.
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Dates et versions

hal-01375516 , version 1 (03-10-2016)

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Simon Rit, Rolf Clackdoyle, Peter Keuschnigg, Philipp Steininger. Filtered-backprojection reconstruction for a cone-beam computed tomography scanner with independent source and detector rotations. Medical Physics, 2016, 43, pp.2344. ⟨10.1118/1.4945418⟩. ⟨hal-01375516⟩
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