Novel digital K-edge imaging system with transition radiation from an 855 MeV electron beam

• Main Authors: Hagenbuck, F., Backe, H., Clawiter, N., Euteneuer, H., Gorgen, F., Holl, P., Johann, K., Kaiser, K.-H., Kemmer, J., Kerschner, Th, Kettig, O., Koch, H., Kube, G., Lauth, W., Matthay, H., Schutrumpf, M., Stotter, R., Struder, L., Walcher, Th, Wilms, A., Von Zanthier, C., Zemter, M.
• Format: Conference Proceeding
• Language: English
• Subjects: Copper; Detectors; Electromagnetic wave absorption; Electron beams; Energy measurement; Imaging phantoms; Object detection; Optical imaging; Photonic crystals; X-ray imaging
• ISSN: 1082-3654; 2577-0829
• DOI: 10.1109/NSSMIC.2000.949396

A novel K-edge imaging method has been developed at the Mainz Microtron MAMI aiming at a very efficient use of the transition radiation (TR) flux generated by the external 855 MeV electron beam in a foil stack. A fan-like quasi-monochromatic hard X-ray beam is produced from the /spl plusmn/1 mrad wide TR cone with a highly oriented pyrolytic graphite (HOPG) crystal. The absorption of the object in front of a 30/spl times/10 mm/sup 2/ pn-CCD photon detector is measured at every pixel by a broad band energy scan around the K-absorption edge. This is accomplished by a synchronous variation of the lateral crystal position and the electron beam direction which defines also the direction of the TR code. The system has been checked with a phantom consisting of a 2.5 /spl mu/m thick molybdenum sample embedded in a 136 or 272 /spl mu/m thick copper bulk foil. A numerical analysis of the energy spectrum for every pixel demonstrates that data as far as /spl plusmn/0.75 keV away from the K edge of molybdenum at 20 keV still improve the signal-to-noise ratio. Prospects are discussed to investigate the human lungs with xenon as a contrast agent at the available total primary photon flux of 2/spl middot/10/sup 10//(s/spl middot/0.1% BW) only.