1. A method, comprising: registering first volumetric data, corresponding to an image volume comprising an object of study and an unwanted object, and second volumetric data, corresponding to the unwanted object, in a common coordinate system; removing the unwanted object from the first volumetric data to generate modified first volumetric data; performing a plurality of forward projections on the modified first volumetric data to generate a plurality of planar projection images; constructing a three-dimensional image of the image volume from the plurality of planar projection images, wherein the three-dimensional image does not contain the unwanted object.