Effciency Enhanced Mega Electronvolt Cone Beam Computed Tomography (EMECT) a succession project to the project X-ray 3D Computed Tomography with Mega Electronvolt Source (CTOMES)

• Applicants: Professor Dr. Randolf Hanke; Professor Dr. Stefan Kasperl
• Subject Area: Medical Physics, Biomedical Technology ; Measurement Systems
• Term: from 2012 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 225989123

In this research project proposal we propose a contrast and image quality improvement for Mega Electronvolt (MeV) cone beam X-Ray imaging. The overall idea is to improve the ratio of detected primary to scattered radiation by introducing highly optimized detector-sided filtering. Key part of the proposed work will be the combination with computational tracking and correcting the subsidiary spatial resolution loss of the proposed method, as well as providing a method to track experimentally the introduced improvements in spectral system response and use this for accurate in-silico simulations.High Energy (HE) industrial X-ray Computed Tomography (CT) systems operating with energies exceeding one Mega Electronvolt have been in operation for over a decade. However, due to the large amount of specimen-scattered radiation created at these energies, these systems are typically designed in a fan-beam setting using a linear detector which is usually highly collimated. HE setups could benefit greatly from the increase in speed and resolution provided by a Cone Beam Computed Tomography (CBCT) setup incorporating a flat-panel detector as it is typically used in X-ray systems with lower energies up to 600 Kilo Electronvolt (keV). However, a cone-beam setup in the context of MeV industrial CT often does not have sufficient image quality, due to artifacts caused by radiation, which is scattered from the specimen, the environment and the detector itself. In a cone beam setup such secondary radiation cannot be avoided by collimation, but is the main part of the background signal and decreases both contrast and spatial resolution. The radiographs of a HE system in cone-beam acquisition geometry, suffer from a significant increase in object-scattered radiation. Moreover, commercially available flat-panel detectors are optimized for lower energy X-ray beams, with a scintillation layer that is kept thin in order to avoid a degradation of the Point-Spread Function (PSF) of the imaging system. For MeV industrial CT systems the thin phosphorous screens cause a low detection efficiency due to the low and non-linear conversion of X-ray photons into signal. Investigating those properties experimentally and introducing an improvement term of image contrast by the use of additional detector filtering is purpose of this research project.

• DFG Programme: Research Grants
• International Connection: Switzerland
• Cooperation Partner: Professor Dr. Alex Dommann