3D imaging of human cells using PIXEμCT

We report imaging of human lung epithelial cells exposed to cobalt oxide (Co3O4) microparticles using three-dimensional (3D) particle-induced X-ray emission microcomputed tomography (PIXEμCT). The use of energy-selectable quasi-monochromatic low-energy X-rays generated via proton microbeam bombardment led to high-quality images. We also carried out two-dimensional (2D) micro-PIXE imaging. The 3D PIXEμCT imaging data are complementary with 2D micro-PIXE images and the CT value ratios of the cells show that the strong absorption stems from Co3O4. The 2D micro-PIXE analysis provides projection images of the elemental distribution, and this in combination with the 3D PIXEμCT imaging revealed details of the internal distribution of Co3O4, and hence provides insight into the mechanisms of Co3O4 toxicity via intracellular perinuclear accumulation.