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Recent trends in hard X-ray micro-computed tomography (microCT) aim at increasing both spatial and temporal resolutions. These challenges require intense photon beams. Filtered synchrotron radiation beams, also referred to as `pink beams', which are emitted by wigglers or bending magnets, meet this need, owing to their broad energy range. In this work, the new microCT station installed at the biomedical beamline ID17 of the European Synchrotron is described and an overview of the preliminary results obtained for different biomedical-imaging applications is given. This new instrument expands the capabilities of the beamline towards sub-micrometre voxel size scale and simultaneous multi-resolution imaging. The current setup allows the acquisition of tomographic datasets more than one order of magnitude faster than with a monochromatic beam configuration.

In this work a double-crystal setup is employed to study compound refractive lenses made of single-crystal diamond. The point spread function of the lens is calculated taking into account the lens transmission, the wavefront aberrations, and the ultra-small-angle broadening of the X-ray beam. It is shown that, similarly to the wavefront aberrations, the ultra-small-angle scattering effects can significantly reduce the intensity gain and increase the focal spot size. The suggested approach can be particularly useful for the characterization of refractive X-ray lenses composed of many tens of unit lenses.A double-crystal setup is used to quantify aberrations and to assess the influence of ultra-small-angle X-ray scattering on the optical properties of a single-crystal diamond compound refractive lens.

Medical imaging and radiation therapy are widely used synchrotron-based techniques which have one thing in common: a significant dose delivery to typically biological samples. Among the ways to provide the experimenters with image guidance techniques indicating optimization strategies, Monte Carlo simulation has become the gold standard for accurately predicting radiation dose levels under specific irradiation conditions. A highly important hampering factor of this method is, however, its slow statistical convergence. A track length estimator (TLE) module has been coded and implemented for the first time in the open-source Monte Carlo codeGATE/Geant4. Results obtained with the module and the procedures used to validate them are presented. A database of energy-absorption coefficients was also generated, which is used by the TLE calculations and is now also included inGATE/Geant4. The validation was carried out by comparing the TLE-simulated doses with experimental data in a synchrotron radiation computed tomography experiment. The TLE technique shows good agreementversusboth experimental measurements and the results of a classical Monte Carlo simulation. Compared with the latter, it is possible to reach a pre-defined statistical uncertainty in about two to three orders of magnitude less time for complex geometries without loss of accuracy.

High-resolution analyser-based X-ray imaging computed tomography (HR ABI-CT) findings on in vitro human breast cancer are compared with histopathology, mammography, computed tomography (CT) and magnetic resonance imaging. The HR ABI-CT images provided significantly better low-contrast visibility compared with the standard radiological images. Fine cancer structures indistinguishable and superimposed in mammograms were seen, and could be matched with the histopathological results. The mean glandular dose was less than 1 mGy in mammography and 12-13 mGy in CT and ABI-CT. The excellent visibility of in vitro breast cancer suggests that HR ABI-CT may have a valuable role in the future as an adjunct or even alternative to current breast diagnostics, when radiation dose is further decreased, and compact synchrotron radiation sources become available.

International audience; The technical feasibility of temporal and spatial fractionations of the radiation dose has been evaluated using synchrotron microbeam radiation therapy for brain tumors in rats. A significant increase in lifespan (216%, p < 0.0001) resulted when three fractions of microbeam irradiation were applied to the tumor through three different ports, orthogonal to each other, at 24 h intervals. However, there were no long-term survivors, and immunohistological studies revealed that 9 L tumors were not entirely ablated.

Several synchrotrons around the world are currently developing innovative radiotherapy techniques with the aim of palliating and possibly curing human brain tumors. Amongst them, microbeam radiation therapy (MRT) and, more recently, minibeam radiation therapy (MBRT) have shown promising results. In MBRT the beam thickness ranges from 500 to 700 microm with a separation between two adjacent minibeams of the same value, whilst in MRT the thickness is of the order of 25-50 microm with a distance between adjacent microbeams of the order of 200 microm. An original method has been developed and tested at the ESRF ID17 biomedical beamline to produce the minibeam patterns. It utilizes a specially developed high-energy white-beam chopper whose action is synchronized with the vertical motion of the target moving at constant speed. Each opening of the chopper generates a horizontal beam print. The method described here has the advantage of being simple and reliable, and it allows for an easy control of the patient safety in future clinical trials. To study the feasibility of the method, dosimetric measurements have been performed using Gafchromic HD-810 films and compared with Monte Carlo simulations. The results of this comparison are discussed.

A fixed-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 first 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(-1) mm(-2) under typical operating conditions. The harmonic content of a 25 keV beam is about 30% at the minimum wiggler gap of 25 mm (field 1.57 T) and decreases by an order of magnitude when the gap is increased to 60 mm (field 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.