A method of detecting and/or identifying a material or article in a volume of interest, the volume of interest including a plurality of voxels, the method including: a) detecting, with an input hodoscope (12, 16), charged particles entering the volume of interest, the charged particles being electrons/positrons and muons; b) detecting, with an output hodoscope (14, 18), charged particles leaving the volume of interest, the charged particles being muons or electrons/positrons and muons; c) associating charged particles leaving the volume of interest with charged particles entering the volume of interest and determining therefrom a set of completed trajectories for the associated charged particles; d) performing filtering based on the deflection angles in the input and/or the output hodoscopes of the particles with completed trajectories; e) calculating a volume density map by using back projection of the filtered completed trajectories which passed through each respective voxel, the map representing a number of completed trajectories and/or a scattering angle; and f) detecting and/or identifying the material or article in the volume of interest from the volume density map, wherein in operations c, d and e the set of completed trajectories consists of completed trajectories having associated deflection angles within a specific range of deflections, and characterized in that the method includes selecting the range or ranges of deflection angles such that the electrons and muons are at least partly separated. a) detecting, with an input hodoscope (12, 16), charged particles entering the volume of interest, the charged particles being electrons/positrons and muons; b) detecting, with an output hodoscope (14, 18), charged particles leaving the volume of interest, the charged particles being muons or electrons/positrons and muons; c) associating charged particles leaving the volume of interest with charged particles entering the volume of interest and determining therefrom a set of completed trajectories for the associated charged particles; d) performing filtering based on the deflection angles in the input and/or the output hodoscopes of the particles with completed trajectories; e) calculating a volume density map by using back projection of the filtered completed trajectories which passed through each respective voxel, the map representing a number of completed trajectories and/or a scattering angle; and f) detecting and/or identifying the material or article in the volume of interest from the volume density map, wherein in operations c, d and e the set of completed trajectories consists of completed trajectories having associated deflection angles within a specific range of deflections, and characterized in that the method includes selecting the range or ranges of deflection angles such that the electrons and muons are at least partly separated. wherein in operations c, d and e the set of completed trajectories consists of completed trajectories having associated deflection angles within a specific range of deflections, and characterized in that the method includes selecting the range or ranges of deflection angles such that the electrons and muons are at least partly separated.