Patent ID: 8306180

Claim:
An image reconstruction method in a high-energy dual-energy CT system for cargo inspection comprising: scanning an object with high-energy dual-energy rays to obtain high-energy dual-energy projection values, wherein the high-energy dual-energy rays have energy higher than 1 MeV; calculating projection values of base material coefficients corresponding to the dual-energy projection values on the basis of a pre-created lookup table or by analytically solving a set of equations, wherein the linear attenuation coefficient of each of the materials contained in the scanned object is represented by a linear combination of the linear attenuation coefficients of two selected base materials as in a first formula: μ=b i μ 1 +b 2 μ 2 , where μ denotes the linear attenuation coefficient of the material, μ 1 , μ 2 are the linear attenuation coefficients of the two base materials, b 1 and b 2 are base material coefficients for the material, wherein the first formula establishes a base material decomposition model for representing the linear combination of the linear attenuation coefficients of the two selected base materials with respect to merely Compton effect and Electron pair effect; obtaining an image of base material coefficient distribution based on the projection values of base material coefficients; and calculating both an atomic number image and a characteristic density image of the detected object based on the image of base material coefficient distribution by using the second formula: Z eff = b 1 ⁢ ρ e ⁢ ⁢ 1 ⁢ Z 1 + b 2 ⁢ ρ e ⁢ ⁢ 2 ⁢ Z 2 b 1 ⁢ ρ e ⁢ ⁢ 1 + b 2 ⁢ ρ e ⁢ ⁢ 2 ρ e = b 1 ⁢ ρ e ⁢ ⁢ 1 + b 2 ⁢ ρ e ⁢ ⁢ 2 in which ρ e1 , ρ e2 represent the two base material's densities respectively, Z 1 , Z 2 represent the two base material's atomic numbers respectively, and Z eff denotes an equivalent physical quantity representing the atomic number of the scanned object, and ρ e denotes an equivalent physical quantity representing the characteristic density of the scanned object.