Provided are an apparatus and method for K-edge based interior tomography image processing. The apparatus efficiently performs tomography image reconstruction by acquiring different material images using an energy-selective detector, such as a photon counting detector. The apparatus includes a projection image acquisition unit configured to inject a contrast agent into an object and acquire projection images using the energy-selective detector with respect to a K-edge of the material, a parameter initialization unit configured to initialize parameters needed for image reconfiguration, an ROI interior reconstruction unit configured to perform reconstruction for image reconfiguration until initial convergence is achieved in order to reconstruct an interior of a region of interest, a concentration and correction value calculation unit configured to calculate a concentration and a correction value (β) using a linear attenuation coefficient of the contrast agent and a linear attenuation coefficient of blood, which are known, in the acquired and reconstructed image.
