Development of novel ultrafast-laser-based micro-CT system for small-animal imaging

We investigated the performance of an ultrafast-laser-based X-ray source as a possible replacement of a microfocal X-ray tube in a micro-CT system for small-animal imaging. Using a number of solid targets (Ge, Mo, Ag, Sn, BaF/sub 2/, La, and Nd) with matching filters, we optimized conditions for X-ray generation and measured X-ray spectra, conversion efficiency, X-ray fluence, and X-ray focal-spot size. We obtained images of small animals. X-ray spectra created by ultrafast laser are advantageous for micro-CT imaging because most of the emission is in narrow characteristic lines. The spectra could be rapidly changed and matched to the imaging task (e.g. animal thickness and density). This novel X-ray source can be also easily applied in dual-energy micro-CT for small-animal imaging with suitable contrast agent (e.g. I-, Ba-, or Gd-based) and matching targets and filters for low- and high-energy beams. We have established that the effective X-ray focal-spot size can be smaller than 5 /spl mu/ and that the average power can surpass the power delivered by a microfocal X-ray tube with 5 /spl mu/m focal-spot size.