SNR performance comparison of dual-layer detector and dual-kVp spectral CT

Tube-based dual-kVp and detector-based dual- layer sandwich detector CT systems can be used to generate spectral CT data. We investigate the influence of their energy weighting functions on the performance of reconstructed base material coefficient images and projections. A Monte-Carlo (MC) simulation of the noise propagation for typical water and bone CT projections is used. We find a large difference in the SNR of the reconstructed coefficient projections. Dual-kVp scanning methods yield a factor of 2 better SNR in the coefficient projections than dual-layer detector based CT. This can be explained by the degree of overlap of the weighting functions, especially for low-energy X-ray quanta.