SpectralK-edge subtraction imaging

Abstract

We describe a spectral x-ray transmission method to provide images of independent material components of an object using a synchrotron x-ray source. The imaging system and process is similar to K-edge subtraction (KES) imaging where two imaging energies are prepared above and below the K-absorption edge of a contrast element and a quantifiable image of the contrast element and a water equivalent image are obtained. The spectral method, termed 'spectral-KES' employs a continuous spectrum encompassing an absorption edge of an element within the object. The spectrum is prepared by a bent Laue monochromator with good focal and energy dispersive properties. The monochromator focuses the spectral beam at the object location, which then diverges onto an area detector such that one dimension in the detector is an energy axis. A least-squares method is used to interpret the transmitted spectral data with fits to either measured and/or calculated absorption of the contrast and matrix material-water. The spectral-KES system is very simple to implement and is comprised of a bent Laue monochromator, a stage for sample manipulation for projection and computed tomography imaging, and a pixelated area detector. The imaging system and examples of its applications to biological imaging are presented. The system is particularly well suited for a synchrotron bend magnet beamline with white beam access.

Phase-preserving beam expander for biomedical X-ray imaging

“…In order to meet the physical constraints of the rail system installed in the BMIT-BM beamline hutch, we tolerated a slight deviation from the magic condition, specifically a Bragg angle of 6.56 . From previous work (Zhu et al, 2014), we knew that this Bragg angle adequately approximates the magic condition and, furthermore, corresponds to the K-edge of iodine, allowing us to confirm the energy. Ideally we would have preferred to choose this energy first and then obtain custom-cut crystals to match, but this was not feasible for this experiment.…”

Design of a mouse restraint for synchrotron-based computed tomography imaging

“…2a) and lateral views (Fig. 2b) were obtained using a spectral K-edge subtraction (spectral-KES) (Zhu et al, 2014) imaging setup with a Hamamatsu C9252DK-14 flatpanel detector with 100 mm pixel size. With the mouse/ restraint rotating 180 , 600 projections were captured at equal radial intervals with a 30 ms exposure time for each projection (Fig.…”

Performance of K -edge subtraction tomography as an application of parametric x-ray radiation

“…Although the sample size is restricted by the third crystal area, simultaneous KES-CT is possible by rotating the sample on one vertical axis. This is an advantage of the PXR-based KES compared to the simultaneous KES conducted using a bent-crystal system, referred to as spectral-KES at some SR facilities [26][27][28].…”