Fixed-exit monochromator for computed tomography with synchrotron radiation at energies 18–90 keV

Abstract

A ®xed-exit monochromator has been constructed for computed tomography (CT) studies at the Medical Beamline of the European Synchrotron Radiation Facility. A non-dispersive pair of bent Laue-type crystals is used, and the ®rst crystal is water-cooled. The monochromator operates at energies from 18 to 90 keV, and the maximum width of the beam is 150 mm. The performance of the monochromator is studied with respect to the beam intensity and energy distributions, and a close agreement is found between the calculated and experimental results. The intensity is between 10 9 and 10 10 photons s À1 mm À2 under typical operating conditions. The harmonic content of a 25 keV beam is about 30% at the minimum wiggler gap of 25 mm (®eld 1.57 T) and decreases by an order of magnitude when the gap is increased to 60 mm (®eld 0.62 T). The experimental set-up for CT studies includes dose monitors, goniometers and translation stages for positioning and scanning the object, and a 432-element linear-array Ge detector. Examples from phantom studies and in vivo animal experiments are shown to illustrate the spatial resolution and contrast of the reconstructed images.

Cure of Fisher Rats Bearing Radioresistant F98 Glioma Treated with cis -Platinum and Irradiated with Monochromatic Synchrotron X-Rays

“…The dose rate delivered by synchrotron radiation is directly proportional to the storage ring current and was set at 0.1 Gy/scan at the center of the tube. The beam energy was precisely tuned, either 400 eV above (78.8 keV) or below (78.0 keV) the K-edge absorption of platinum (78.4 keV), with an energy bandwidth of 80 eV (35). Other series of experiments have been performed at 30, 40 and 85 keV.…”

Quantitative Functional Imaging and Kinetic Studies With High‐z Contrast Agents Using Synchrotron Radiation Computed Tomography

“…3 Tuneable monochromatic beams (a few tens to a few hundreds of eV bandwidth) can be separated from the continuous radiation (20-90 keV) by using dedicated X-ray optical devices, such as bent Laue crystals, which is the case at the ESRF. 8,9 The monochromatic photon flux is sufficient to perform any clinical or preclinical medical imaging that could be done with a conventional CT scanner. 10,11 There is no beam hardening, so that the SRCT images do not need any correction procedure and are directly expressed in absolute linear attenuation coefficients, according to the straightforward application of Beer's law in the filtered back-projection reconstruction: (-x) where N/N 0 is the proportion of monochromatic photons (energy E 0 ) that have not been attenuated after having travelled a path of length x in a material of linear attenuation coefficient μ (at energy E 0 ).…”

<title>Very-low-dose mammography: new perspectives in diffraction enhanced imaging (DEI) mammography</title>

“…The storage ring is a 6 GeV machine and the X-ray source is a 21 pole wiggler with variable magnetic field ( max B = 1.6 Tesla). The beam has gaussian a shape in the horizontal and vertical directions and presents a white spectrum; it is monochromatized by a double Si(111) bent crystal monochromator in the Laue geometry 17 . The energy band-pass of the monochromator depends on the crystal curvature.…”