Patent ID: 8411822

Claim:
A method for analyzing material in a voxel of a target, the method comprising: (a) illuminating the voxel of the target with a photon beam; (b) measuring with at least one photon detector a first number of photons scattered from the voxel in a first predetermined energy range and in a first predetermined measurement direction; (c) measuring with at least one photon detector a second number of photons scattered from the voxel in a second predetermined energy range and in a second predetermined measurement direction; (d) determining in a processor a ratio of the first number of photons to the second number of photons; (e) determining in a processor an average atomic number of the material in the voxel using the ratio; (f) choosing at least one predetermined average atomic number range; (g) based upon the average atomic number determined not being within any chosen predetermined average atomic number range, taking no further action with respect to the voxel; and (h) based upon the average atomic number determined being within a chosen predetermined average atomic number range, taking an action with respect to the voxel chosen from the group consisting of: scanning the voxel at a higher resolution; performing a NRF scan of the voxel; scanning the voxel with another scanning method; displaying in an output device an image of at least a part of the target to an operator; and notifying the operator by means of an output device of a potential threat.