Radiation therapy at compact Compton sources

The principle of the compact Compton source is presented briefly. In collision with an ultrarelativistic electron bunch a laser pulse is back-scattered as hard X-rays. The radiation cone has an opening of a few mrad, and the energy bandwidth is a few percent. The electrons that have an energy of the order of a few tens of MeV either circulate in storage ring, or are injected to a linac at a frequency of 10-100 MHz. At the interaction point the electron bunch collides with the laser pulse that has been amplified in a Fabry-Perot resonator. There are several machines in design or construction phase, and projected fluxes are 1012 to 10(14) photons/s. The flux available at 80 keV from the ThomX machine is compared with that used in the Stereotactic Synchrotron Radiation Therapy clinical trials. It is concluded that ThomX has the potential of serving as the radiation source in future radiation therapy programs, and that ThomX can be integrated in hospital environment. (C) 2015 Published by Elsevier Ltd on behalf of Associazione Italiana di Fisica Medica.Peer reviewe

Functional lung imaging with synchrotron radiation : Methods and preclinical applications

Many lung disease processes are characterized by structural and functional heterogeneity that is not directly appreciable with traditional physiological measurements. Experimental methods and lung function modeling to study regional lung function are crucial for better understanding of disease mechanisms and for targeting treatment. Synchrotron radiation offers useful properties to this end: coherence, utilized in phase-contrast imaging, and high flux and a wide energy spectrum which allow the selection of very narrow energy bands of radiation, thus allowing imaging at very specific energies. K-edge subtraction imaging (KES) has thus been developed at synchrotrons for both human and small animal imaging. The unique properties of synchrotron radiation extend X-ray computed tomography (CT) capabilities to quantitatively assess lung morphology, and also to map regional lung ventilation, perfusion, inflammation and biomechanical properties, with microscopic spatial resolution. Four-dimensional imaging, allows the investigation of the dynamics of regional lung functional parameters simultaneously with structural deformation of the lung as a function of time. This review summarizes synchrotron radiation imaging methods and overviews examples of its application in the study of disease mechanisms in preclinical animal models, as well as the potential for clinical translation both through the knowledge gained using these techniques and transfer of imaging technology to laboratory X-ray sources.Peer reviewe

Directional lithium hydride Compton profiles of 0.1% statistical accuracy

Peer reviewe

Hole depletion and localization due to disorder in insulating PrBa2Cu3O7-d: a Compton scattering study

The (mostly) insulating behaviour of PrBa2Cu3O7-d is still unexplained and even more interesting since the occasional appearance of superconductivity in this material. Since YBa2Cu3O7-d is nominally iso-structural and always superconducting, we have measured the electron momentum density in these materials. We find that they differ in a striking way, the wavefunction coherence length in PrBa2Cu3O7-d being strongly suppressed. We conclude that Pr on Ba-site substitution disorder is responsible for the metal-insulator transition. Preliminary efforts at growth with a method to prevent disorder yield 90K superconducting PrBa2Cu3O7-d crystallites.Comment: 4 pages, 3 figures, revised version submitted to PR

Refraction and scattering of X-rays in analyzer-based imaging.

International audienceA new algorithm is introduced for separation of the scattered and non-scattered parts of a monochromatic and well collimated synchrotron radiation beam transmitted through a sample and analyzed by reflection from a perfect crystal in the non-dispersive setting. The observed rocking curve is described by the Voigt function, which is a convolution of Lorentzian and Gaussian functions. For the actual fitting, pseudo-Voigtians are used. The fit yields the scaled integrated intensity (the effect of absorption), the center of the rocking curve (the effect of refraction), and the intensity of the transmitted beam is divided into the scattered and non-scattered parts. The algorithm is tested using samples that exhibit various degrees of refraction and scattering. Very close fits are achieved in an angular range that is 15 times the full width at half-maximum of the intrinsic rocking curve of the analyzer. The scattering part has long tails of Lorentzian shape owing to the ;long-slit geometry' of the set-up. Quantitative images of absorption, refraction and scattering are constructed and compared with results of earlier treatments. The portion of scattering and the second moment of the observed rocking curve both increase linearly with the sample thickness and yield identical maps of the effects of scattering. The effects of refraction are calculated using the geometrical optics approximation, and a good agreement with experiment is found. The fits with reduced number of data points (minimum number is five) yield closely the same results as fits to the full data set