Dual-Energy Micro-CT Using GAGG:Ce and LYSO:Ce Scintillators

Abstract

Dual-energy computed tomography (CT) has a better material determination capability than traditional CT. In this article, we develop a dual-layer dual-energy micrometer CT (DEMCT) imaging system with micrometer spatial resolution. The detector of the DEMCT system uses cerium-doped gadolinium aluminum gallium garnet (GAGG:Ce) and cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) scintillators to absorb X-rays of different energies, which is a new application of GAGG:Ce scintillator. As GAGG:Ce and LYSO:Ce have high light yields and their emission wavelengths match well with the quantum efficiency of common charge-coupled device (CCD), thicknesses of the scintillators are allowed to be thin, which is of great significance for high-resolution imaging due to the limitation of the depth of field of objectives. We propose a mechanical adjustment method for registering high-energy and low-energy images, which saves the postprocessing time and avoids oscillating or nonconvergent iteration results of mathematical registration methods. Meanwhile, in order to increase the dual-energy spectra separation of materials detection in the DEMCT, a fast optimal kilovolt peak selection method is proposed. Results show that the DEMCT has the spatial resolution of 2 μm in low-energy imaging and 4 μm in high-energy imaging. In addition, materials of a silica mixture sample are clearly separated by the pixel selection of the energy map based on the DEMCT data. The proposed DEMCT system has the potential to separate materials that cannot be correctly determined on traditional CT.