1. A method for analyzing an item, comprising acts of: a) analyzing scan data that provides a projection of the item to determine at least one first characteristic of at least one object in the item; b) selecting, based on the projection, a region of the item that includes the at least one object; c) performing a computed tomographic reconstruction of the selected region to produce a reconstructed representation of the selected region; d) analyzing the reconstructed representation to determine at least one second characteristic of the at least one object; and e) using the at least one first characteristic and the at least one second characteristic after a region of the item is selected to determine whether the item contains a threat object.