High-energy 3-D X-ray tomography for container inspection

Within the ECSIT project, Fraunhofer EMI and EZRT evaluated methods and technologies to enable high-energy 3-D imaging for inspection of large objects like sea freight containers. In particular, the efforts focused on the following: high-energy 3-D X-ray physics, inspection procedures for large objects, material-selective Computed Tomography (CT), 2-D and 3-D image processing to support the detection of illicit contents in packed goods and the development of radiation-resistant X-ray sensors as well as high-intensity X-ray sources. The physical aspects of transmission measurements were optimized based on a simulation study. Among these parameters were the distance of the linear accelerator's focus to the rotational axis, the spatial resolution in dependency on the pixel pitch of a linear detector array (LDA) with 10,000 elements, and collimation as well as alignment of the X-ray fan. To test the system we used a 10'-container packed with various typical goods like furniture or consumer electronics. Filtered back-projection techniques were applied to reconstruct slice images from about 800 projections. We show real 3-D volume data of large objects measured with the set-up as described above. A first qualitative evaluation shows the capability of the high-energy CT-system to deliver images that allow for a recognition of various items by shape, size and internal construction. In addition, the images allow for an estimation of the mass density of larger amounts of homogeneous materials.