1. A method for reconstructing and segmenting an image of the contents of a container, said method comprising: (i) receiving actual scan data from a scan of the container; (ii) reconstructing the actual scan data to obtain a reconstructed image; (iii) segmenting the reconstructed image to obtain a segmented image; (iv) deriving simulated scan data corresponding to the segmented image; (v) calculating an error term based on a difference between the simulated scan data and the actual scan data; (vi) determining whether a criterion is satisfied; (vii) using the error term to produce a modified reconstructed image and repeating steps (iii) through (vii) with the modified reconstructed image substituted for the reconstructed image obtained in step (ii), if the criterion is not satisfied; and (viii) outputting information from the segmented image if the criterion is satisfied.