Abstract: A method of detecting and/or identifying a material or article in a volume of interest, comprises: a) detecting, with an input hodoscope, charged particles entering the volume of interest, b) detecting, with an output hodoscope, charged particles leaving the volume of interest, c) associating particles leaving the volume of interest with particles entering the volume of interest and determining therefrom a set of completed trajectories for the particles, d) performing filtering based on the deflections of the particles with completed trajectories, e) calculating a volume density map based on the filtered completed trajectories which passed through each respective voxel, the map representing a number of completed trajectories and/or a total scattering angle; and f) detecting and/or identifying the material or article in the volume of interest from the volume density map.