A bent Laue{endash}Laue monochromator for a synchrotron-based monochromatic x-ray computed tomography system
- Medical Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)
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 method 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.}
- OSTI ID:
- 670211
- Journal Information:
- Medical Physics, Journal Name: Medical Physics Journal Issue: 12 Vol. 25; ISSN 0094-2405; ISSN MPHYA6
- Country of Publication:
- United States
- Language:
- English
Similar Records
Beam-smiling in bent-Laue monochromators
A tunable Laue/bent-Laue monochromator with fixed second crystal for synchrotron radiation