Fast X-ray imaging using a position sensitive proportional counter

An X-ray imaging method based on image reconstruction from projections has been established by analogy to medical computed tomography (CT). Where CT uses transmission, X-ray imaging (X-ray macroscopy, XMA) uses reflection. Using an energy-dispersive Si(Li) detector and performing translation and rotation steps of the sample across the line focused X-ray beam separately and sequentially, X-ray imaging suffers from long data acquisition times (several hours). A position sensitive proportional counter (PSPC) has been used to generate a complete translation profile (projection) simultaneously. The sample is illuminated by an X-ray cone and the reflected fluorescence intensity distribution imaged on to the PSPC by an imaging slit. Scanning movements are reduced to sample rotations; sample translation is not required. Preliminary experiments have shown that data acquisition times are shortened by a factor of ten. An experimental arrangement for fast tomographic imaging, results and some problems arising from using a PSPC are discussed. Finally, a second direct imaging experiment, equivalent to scanning the sample across a point-focused X-ray beam, is introduced. (author)