Micron-CT using PIXE

Abstract

  In ion-atom collision, generally, the production cross sections of characteristic X-rays are very large in comparison to those of continuous X-rays, which when integrated over the detector resolution are typically 3 orders of magnitude smaller. Due to this inherent advantage, characteristic X-rays can be considered as monochromatic X-ray source. We apply this feature to X-ray CT, where usually continuous X-rays are used. When using monochromatic X-rays, images reflecting the elemental distributions within the objects are obtained and by using micro-beams, cross sectional images with a spatial resolution of about 1 μm can be provided. On the basis of this idea, we developed a novel micron-CT consisting of a micro-beam system and an X-ray CCD camera. A tube holding samples was rotated by a stepping motor and the transmission images of the samples were taken with characteristic K-X-rays of Ti (4.558 keV) produced by 3MeV proton micro-beams. After image reconstruction using an iteration method, images of cross sections of small objects with a spatial resolution of 3μm were obtained. It is expected that our micron-CT can provide cross sectional images of in-vivo cellular samples with high resolution and can be applied to a wide range of researches in biology and medicine.