Differential phase contrast CT — Characterics of signal and noise

The differential phase contrast CT (DPC-CT) implemented with x-ray tube and grating is emerging as a new technology to improve the contrast sensitivity of the conventional CT. Via system modeling, analysis and computer simulation, we investigate the DPC-CT´s characteristics of signal and noise and compare them with the conventional CT. The preliminary data show that the DPC-CT possesses a modulation transfer function that is comparable with that of the conventional attenuation-based CT. However, the radical difference in the noise power spectrum between the DPC-CT (1/|k| trait) and the conventional CT (|k| trait) leads to the substantial difference in their spectrum of noise equivalent quanta NEQ(k), which accounts for the significant advantage in DPC-CT imaging performance over the conventional CT at high spatial resolution. It is believed that the finding reported in this paper can provide insightful guidelines on the research and development of DPC-CT for preclinical and clinical applications.