Bassey

Development of a bent Laue beam-expanding double-crystal monochromator for biomedical X-ray imaging

A bent Laue beam-expanding double-crystal monochromator was developed and tested at the Biomedical Imaging and Therapy beamline at the Canadian Light Source. The expander will reduce scanning time for micro-computed tomography and allow dynamic imaging that has not previously been possible at this beamline.

Phase-preserving beam expander for biomedical X-ray imaging

Building on previous work, a phase-preserving bent Laue beam-expanding monochromator was developed with the capability of performing live animal phase contrast dynamic imaging at the Biomedical Imaging and Therapy beamline at the Canadian Light Source.

Multiple energy synchrotron biomedical imaging system.

A multiple energy imaging system that can extract multiple endogenous or induced contrast materials as well as water and bone images would be ideal for imaging of biological subjects. The continuous spectrum available from synchrotron light facilities provides a nearly perfect source for multiple energy x-ray imaging. A novel multiple energy x-ray imaging system, which prepares a horizontally focused polychromatic x-ray beam, has been developed at the BioMedical Imaging and Therapy bend magnet beamline at the Canadian Light Source. The imaging system is made up of a cylindrically bent Laue single silicon (5,1,1) crystal monochromator, scanning and positioning stages for the subjects, flat panel (area) detector, and a data acquisition and control system. Depending on the crystals bent radius, reflection type, and the horizontal beam width of the filtered synchrotron radiation (20-50 keV) used, the size and spectral energy range of the focused beam prepared varied. For example, with a bent radius of 95 cm, a (1,1,1) type reflection and a 50 mm wide beam, a 0.5 mm wide focused beam of spectral energy range 27 keV-43 keV was obtained. This spectral energy range covers the K-edges of iodine (33.17 keV), xenon (34.56 keV), cesium (35.99 keV), and barium (37.44 keV); some of these elements are used as biomedical and clinical contrast agents. Using the developed imaging system, a test subject composed of iodine, xenon, cesium, and barium along with water and bone were imaged and their projected concentrations successfully extracted. The estimated dose rate to test subjects imaged at a ring current of 200 mA is 8.7 mGy s-1, corresponding to a cumulative dose of 1.3 Gy and a dose of 26.1 mGy per image. Potential biomedical applications of the imaging system will include projection imaging that requires any of the extracted elements as a contrast agent and multi-contrast K-edge imaging.

An energy dispersive bent Laue monochromator for K-edge subtraction imaging

K-Edge Subtraction (KES) is a powerful synchrotron imaging method that allows the quantifiable determination of a contrast element (e.g. iodine) and matrix material (usually represented as water) in both projection imaging and computed tomography. A bent Laue monochromator has been developed that has very good focal and energy dispersive properties for KES. Approximately 5% of the vertical beam profile is involved in “edge crossing” energies, thus no splitter is employed as has been done with previous implementations where approximately 33% of the beam size was blocked. The beam can be narrowed vertically allowing a smaller crossover angle than a splitter based system which minimizes artifacts. The combination of good spatial resolution, energy dispersive properties, flux and a unique approach to data analysis make this system nearly ideal for KES.

Multiple Energy Synchrotron Biomedical Imaging System- Preliminary Results

The drive to improve and expand the amount of information extracted from various imaging modalities has led to the use of multiple (usually two) x-ray photon energies in computed tomography clinical systems. With the use of a single photon energy, the ability to differentiate soft from hard tissues is a problem which multiple energy imaging can solve. The continuous spectrum available from synchrotron light facilities provides a nearly an ideal source for multiple energy imaging. For living biological subjects a multiple energy system that can extract multiple endogenous or induced contrast materials as well as water and bone images would be ideal. A novel bent Laue single crystal monochromator that has a wide angularly dispersed energy range (polychromator) has been developed to explore the use of multiple energies simultaneously for biomedical imaging at the Biomedical Imaging and Therapy beamline at the Canadian Light Source. Using the 311 reflection from a 511 silicon crystal wafer bent to a radius of 95 cm, the system prepares a 0.5 mm wide focused polychromatic x-ray beam with a spectral range of 27 keV to 43 keV, covering both the iodine and barium K-edges of 33.17 keV and 37.44 keV, respectively. As an example use, test objects with iodine and barium (common contrast agents used in clinical imaging) along with water and bone were imaged and successfully extracted independent quantifiable images of these four materials. The biomedical imaging system is presented with emphasis on the polychromator used to prepare the imaging beam.

A phase-space beam position monitor for synchrotron radiation

A system has been developed to measure the vertical position and angle of the electron beam at a single location from a synchrotron source. The system uses a monochromator tuned to the absorption edge of a contrast material and has a sensitivity comparable with other beam position monitors.

Small and Ultra-Small Angle X-Ray Scattering Contrast Obtained With a Synchrotron-Based Shack–Hartmann Imaging System

A number of phase based X-ray imaging methods have been developed that derive contrast from phase effects from the object which make them particularly interesting because of the ability to visualize soft tissues. Shack-Hartmann is a wave-front diagnostic technique that emerged from optics which uses ray-line beams (beamlets) to interrogate the differences in the wave-front across a beam can also be used for X-ray imaging applications with phase sensitivity. This method, which has been applied in the X-ray regime, is very simple in that it only requires a screen to prepare an array of beamlets that then pass through the object and are allowed to propagate a distance onto a pixelated detector. Absorption and refraction information can be extracted from the detected beamlets. An untapped property is the additional ability to extract scatter distribution information based on the observed width of the detected spots. This paper describes experiments done at a synchrotron facility investigating the use of a Shack-Hartmann system for biomedical applications and include our method and examples of scatter contrast extraction from the method.