DETECTING AND QUANTIFYING MATERIALS IN CONTAINERS UTILIZING AN INVERSE ALGORITHM WITH ADAPTIVE REGULARIZATION

摘要

A method, system and computer program product for automatically detecting and quantifying materials in containers (e.g., luggage, storage containers, equipment or componentry for processing or handling). An X-ray radiograph of a container is generated. A set of materials of interest (e.g., plutonium, steel) is selected to determine if the object comprises or contains materials of interest. An estimate of the areal densities or thicknesses of each of the selected materials of interest is obtained by minimizing an objective function with respect to the areal densities or thicknesses for each of the selected materials of interest. Adaptive regularization is implemented in the objective function to improve optimization results by adding a constraint to the objective function, where the constraint penalizes the objective function for solutions that do not line up with a prior belief about the solution form (e.g., the solution should not be negative or especially noisy).

主权项

1. A method for automatically detecting or quantifying a presence of a material in a container, the method comprising:
generating a radiograph from a detector response at a detector array, wherein said detector array detects a transmitted beam which emerges from an object in a container, wherein said transmitted beam is a portion of a flux in an X-ray beam that is not attenuated by said object; selecting a set of materials of interest used to determine if said object in said container corresponds to one or more of these materials of interest; obtaining, by a processor, estimated areal densities for each of said selected set of materials of interest by minimizing an objective function with respect to said areal densities, or linear attenuation coefficients, for each of said selected set of materials of interest, wherein said objective function comprises a least-squares misfit of a vector containing observed signals at each pixel of said radiograph and a model of said radiography detector response, wherein said minimizing of said objective function occurs by varying a combination and a quantity for each of said selected set of materials of interest at each pixel of said radiograph model until a minimum of said objective function is found; and implementing adaptive regularization to said objective function to improve optimization results by adding a constraint to said objective function, wherein said constraint penalizes said objective function as sums of differences in material compositions for each of said selected set of materials of interest in column and row dimensions at each pixel of said radiograph.