3D Non-Destructive Fluorescent X-Ray Computed Tomography with a CdTe Array

In this study, we develop 2D and 3D tomographic non-destructive tests for detecting fluorescence X-rays using a 2D CdTe array. Experiments were conducted using various phantoms and image-reconstruction methods. In general, conventional computed tomography analyzes materials according to attenuation coefficients and is highly dependent on the densities of the materials; thus, it is difficult to discriminate materials that have similar densities, even if their atomic numbers differ. In our research, materials were exposed to X-rays, and both conventional transmission images and fluorescent X-ray images were reconstructed using the information from characteristic X-rays detected using a 2D CdTe planar detector array. Since atoms have their own characteristic X-ray energies, our system was able to discriminate materials of the same or similar density if the materials had different atomic numbers. Additionally, the transmission and characteristic X-ray images were combined to analyze the positions, densities, and atomic numbers of the unknown materials. Several image-reconstruction methods were applied; the reconstructed images were compared to determine an optimized algorithm for fluorescence X-ray computed tomography.