X-Tek Systems, a division of Nikon Metrology UK, designs, develops and manufactures microfocus X-ray radiography and computed tomography systems for industrial non-destructive testing. The range of X-ray acceleration voltages of its current standard products is 130-450 kV. It is widely known that X-ray images can be created using phase contrast formed by the natural propagation of X-rays. Simulation of the natural propagation of X-rays through a cylindrical test sample predicted a small contrast peak at the boundary between the cylinder material and air. Comparison data were obtained using an X-ray source with acceleration voltage above 100 kV. The simulation results correlated well with the experimental data. A further practical example (a 'magic mirror' amulet from an old Japanese shrine) is introduced and discussed. In this specimen, we detected intensity variation including the effect of phase contrast in the operating region above 100 kV. In summary, natural propagation phase contrast was observed in radiographic images from a standard point X-ray source with acceleration voltages exceeding 100 kV.
Keywords: natural propagation; phase contrast; point X-ray source.