METAL ARTIFACTS REDUCTION IN CONE BEAM RECONSTRUCTION

A method for reducing metal artifacts in a volume radiographic image reconstructs a first 3-D-image using measured projection images and forms a 3-D image metal mask that contains metal voxels. For each measured projection image, a projection metal mask is a projection of the 3-D image metal mask. A 3-D prior image contains voxels within the 3-D image metal mask. Voxel values of the first 3-D image outside the 3-D image metal mask are replaced with a value representative of air or soft tissue. Non-metal voxels of the 3-D prior image are modified according to a difference between a pixel value related to the nonmetal voxel and the corresponding pixel value in a calculated projection image. Composite projection images are formed by replacing measured projection image data for pixels within the projection metal mask with calculated projection image data. A metal artifact reduced 3-D image is reconstructed from composite projections.