Preliminary study on phase-contrast digital tomosynthesis: Development and evaluation of experimental system

The advantage of X-ray phase imaging is its ability to obtain information on soft tissues, which is difficult using conventional X-ray imaging. Moreover, a sharp X-ray image can be obtained from the edge effect resulting from phase contrast. Digital tomosynthesis is an imaging technique used to reconstruct multiple planes in a single scan. In this study, we developed an experimental system that combines the phase-contrast and digital tomosynthesis techniques. Our experimental system consists of a transmission-type micro-focus X-ray source (minimum focus size: 1 μm). We also introduced an indirect conversion-type flat panel detector (pixel pitch: 50 μm, matrix size: 2366 × 2368) as an imaging device. The sample is placed on a computer-controlled rotation table, and projection images are captured from various angles. The images are then reconstructed using the filtered back projection method. In the experiments, a tomosynthesis image of an acrylic phantom was obtained at a tube voltage of 40 kV and at a maximum projection angle of ±20°. To evaluate the edge enhancement effect by phase contrast, the resolution, degree of edge enhancement, and image contrast were measured using the acrylic phantom. A good edge enhancement effect was confirmed under the specified conditions. Furthermore, we compared to the shape between the projection image and the tomosynthesis image and found that the tomosynthesis image showed high shape reproducibility compared to the conventional projection image. These results indicate that phase-contrast digital tomosynthesis may be useful for the three-dimensional imaging of low-contrast material.