Send to

Choose Destination
Med Phys. 2016 May;43(5):2344. doi: 10.1118/1.4945418.

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

Author information

Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Department of Radiation Oncology, Centre Léon Bérard, 28 rue Laennec, Lyon 69008, France.
Laboratoire Hubert Curien, CNRS and Université Jean Monnet (UMR5516), 18 rue du Professeur Benoit Lauras, Saint Etienne F-42000, France.
Institute for Research and Development on Advanced Radiation Technologies (radART), Paracelsus Medical University, Strubergasse 16, Salzburg 5020, Austria and medPhoton GmbH, Strubergasse 16, Salzburg 5020, Austria.



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.


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 CT image with an 8.5 cm-offset FOV was also obtained from projections of an anthropomorphic head phantom.


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.


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.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center