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

Abstract

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.

Authors:
 [1]; ;  [2]; ;  [3];  [4];  [5]
  1. Biomedical Engineering Division, University of Saskatchewan, Saskatoon, SK (Canada)
  2. Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK (Canada)
  3. Canadian Light Source Inc., Saskatoon, SK (Canada)
  4. Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK (Canada)
  5. (Canada)
Publication Date:
OSTI Identifier:
22608389
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1741; Journal Issue: 1; Conference: SRI2015: 12. international conference on synchrotron radiation instrumentation, New York, NY (United States), 6-10 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; APPROXIMATIONS; BEAM PROFILES; BEAMS; COMPUTERIZED TOMOGRAPHY; DATA ANALYSIS; IMAGES; MONOCHROMATORS; SPATIAL RESOLUTION; SYNCHROTRONS

Citation Formats

Samadi, Nazanin, E-mail: Nazanin.Samadi@usask.ca, Martinson, Mercedes, Bassey, Bassey, Gomez, Ariel, Belev, George, Chapman, Dean, and Canadian Light Source Inc., Saskatoon, SK. An energy dispersive bent Laue monochromator for K-edge subtraction imaging. United States: N. p., 2016. Web. doi:10.1063/1.4952876.
Samadi, Nazanin, E-mail: Nazanin.Samadi@usask.ca, Martinson, Mercedes, Bassey, Bassey, Gomez, Ariel, Belev, George, Chapman, Dean, & Canadian Light Source Inc., Saskatoon, SK. An energy dispersive bent Laue monochromator for K-edge subtraction imaging. United States. doi:10.1063/1.4952876.
Samadi, Nazanin, E-mail: Nazanin.Samadi@usask.ca, Martinson, Mercedes, Bassey, Bassey, Gomez, Ariel, Belev, George, Chapman, Dean, and Canadian Light Source Inc., Saskatoon, SK. 2016. "An energy dispersive bent Laue monochromator for K-edge subtraction imaging". United States. doi:10.1063/1.4952876.
@article{osti_22608389,
title = {An energy dispersive bent Laue monochromator for K-edge subtraction imaging},
author = {Samadi, Nazanin, E-mail: Nazanin.Samadi@usask.ca and Martinson, Mercedes and Bassey, Bassey and Gomez, Ariel and Belev, George and Chapman, Dean and Canadian Light Source Inc., Saskatoon, SK},
abstractNote = {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.},
doi = {10.1063/1.4952876},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1741,
place = {United States},
year = 2016,
month = 7
}
  • A bent Bragg–Laue monochromator (BLM) is proposed for high-energy X-ray (~25–60 keV) beamlines. The BLM has the unique feature of bi-directional focusing. A sagittally bent Laue crystal can focus the large horizontal fan of a bending magnet or wiggler source. A meridionally bent Bragg crystal focuses the beam vertically and corrects for the anticlastic bending effects of the Laue crystal. This monochromator geometry relies on the crystal orientations being optimized. We show that the focusing condition and Rowland condition can be simultaneously satisfied at a given energy. A detailed ray tracings indicate that a BLM can provide similar energy resolutionmore » and higher flux density compared to a sagittally bent double-Laue monochromator configuration. A prototype BLM with a symmetric Bragg crystal and an asymmetric Laue crystal was tested. Matching of the bend radii of the two crystals in the meridional direction was demonstrated. Generally, the horizontal acceptance of the sagittally bent Laue crystal is limited by the large curvature. This horizontal BLM acceptance could be increased by translating the Laue crystal along its sagittal bending axis.« less
  • No abstract prepared.
  • A bent Laue{endash}Laue monochromator for wide, fan-shaped synchrotron x-ray beams was designed and constructed for the program Multiple Energy Computed Tomography (MECT) at the National Synchrotron Light Source (NSLS). MECT uses monochromatic x-ray beams from the NSLS{close_quote}s X17B beamline for CT with improved image contrast-to-noise ratio, image quantification, and the efficacy for dual-energy imaging. The new monochromator uses two Czochralski-grown Si{l_angle}111{r_angle} crystals, which are 0.7 and 1.4 mm thick, respectively, and are cut with thick ribs on their upper and lower ends. The crystals are bent cylindrically, using 4-rod benders employing two fixed and two movable rods. The bent-crystal methodmore » was needed to solve the difficulties we had with the flat Laue{endash}Laue monochromator previously used in MECT; these included: (a) insufficient beam intensity, (b) excessive beam-intensity fluctuations, and (c) instability of the beam{close_quote}s horizontal profile shape. Compared with flat Laue{endash}Laue monochromator, the bent Laue{endash}Laue device tested at 42 keV and 108 keV showed {approximately}10-fold increase in the beam flux, {approximately}5-fold improvement of beam-profile stability, {approximately}10-fold suppression of beam harmonic contamination at the bending radius of 15 m, and a smaller energy bandwidth at certain bending radii. The new monochromator should reduce MECT{close_quote}s image noise and artifacts, bringing its performance close to that of the ideal CT. {copyright} {ital 1998 American Association of Physicists in Medicine.}« less
  • A Laue/bent-Laue two crystal monochromator has been developed for producing a monochromatic x-ray fan beam with energy tunable over a wide range by adjusting the angle of only the first flat Laue crystal. Bending the second crystal increases the reflection bandwidth, making the monochromator very stable against vibrations. The monochromator was tuned to above and below the K edge energy of indium at the X12A beam line at the National Synchrotron Light Source for dual energy subtraction imaging. {copyright} {ital 1997 American Institute of Physics.}
  • A Laue/bent-Laue two crystal monochromator has been developed for producing a monochromatic x-ray fan beam with energy tunable over a wide range by adjusting the angle of only the first flat Laue crystal. Bending the second crystal increases the reflection bandwidth, making the monochromator very stable against vibrations. The monochromator was tuned to above and below the K edge energy of indium at the X12A beam line at the National Synchrotron Light Source for dual energy subtraction imaging.