Hybrid decomposition method for dual energy CT

Dual energy CT (DECT) can target to reconstruct the spatial distribution of the electron density and the atomic number or the mass density of materials. In the literature, there are two kinds of processing methods for DECT to incorporate analytically the basis function decomposition. Taking decomposition in projection-domain before spatial reconstruction is referred as pre-processing method, while taking decomposition from the low energy and high energy attenuation images reconstructed directly from two energy projection data is post-processing method. In this paper, we propose a hybrid decomposition method which combines the thoughts of both preprocess and post-process methods. In our method, two distinct virtual monochromatic projection data is firstly estimated. Then, the material information is extracted from virtual monochromatic attenuation images reconstructed. We demonstrate that our method is more accurate than the pre-processing and post-processing method in simulation studies. Furthermore, the virtual monochromatic attenuation, electron density, atomic number and basis material density can be achieved simultaneously by performing a standard reconstruction twice only, which makes the proposed method computational efficient and practical.