Diffraction enhanced imaging (DEI) is a new, synchrotron-based, x-ray radiography method that uses monochromatic, fan-shaped beams, with an analyser crystal positioned between the subject and the detector. The analyser allows the detection of only those x-rays transmitted by the subject that fall into the acceptance angle (central part of the rocking curve) of the monochromator/analyser system. As shown by Chapman et al, in addition to the x-ray attenuation, the method provides information on the out-of-plane angular deviation of x-rays. New images result in which the image contrast depends on the x-ray index of refraction and on the yield of small-angle scattering, respectively. We implemented DEI in the tomography mode at the National Synchrotron Light Source using 22 keV x-rays, and imaged a cylindrical acrylic phantom that included oil-filled, slanted channels. The resulting 'refraction CT image' shows the pure image of the out-of-plane gradient of the x-ray index of refraction. No image artefacts were present, indicating that the CT projection data were a consistent set. The 'refraction CT image' signal is linear with the gradient of the refractive index, and its value is equal to that expected. The method, at the energy used or higher, has the potential for use in clinical radiography and in industry.

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Microbeam therapy is established as a general concept for brain tumour treatment. A synchrotron based x-ray source was chosen for experimental research into microbeam therapy, and therefore new simulations were essential for investigating the therapy parameters with a proper description of the synchrotron radiation characteristics. To design therapy parameters for tumour treatments, the newly upgraded LSCAT (Low energy SCATtering) package of the EGS4 Monte Carlo simulation code was adapted to develop an accurate self-written user code for calculating microbeam radiation dose profiles with a precision of 1 microm. LSCAT is highly suited to this purpose due to its ability to simulate low-energy x-ray transport with detailed photon interactions (including bound electron incoherent scattering functions, and linear polarized coherent scattering). The properties of the synchrotron x-ray microbeam, including its polarization, source spectrum and beam penumbra, were simulated by the new user codes. Two concentric spheres, an inner sphere, defined as a brain, and a surrounding sphere, defined as a skull, represented the phantom. The microbeam simulation was tested using a 3 x 3 cm array beam for small treatment areas and a 6 x 6 cm array for larger ones, with different therapy parameters, such as beam width and spacing. The results showed that the microbeam array retained an adequate peak-to-valley ratio, of five times at least, at tissue depths suitable for radiation therapy. Dose measurements taken at 1 microm resolution with an 'edge-on' MOSFET validated the basics of the user code for microplanar radiation therapy.

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