Simulation study on a photon counting X-ray CT system

In an x-ray CT system the energy fluence of x-rays is commonly measured with a scintillation detector in the data acquisition. Thus it is impossible to consider the shape of the energy spectrum of x-rays incident to the detector. If the data related to the energy spectrum could be measured, it would be possible to decrease the beam-hardening of x-rays and also enhance the contrast of lesions. The aim of this study is to evaluate the effectiveness of a photon counting x-ray CT with simulations. In these simulations we calculated the photons incident to the detector with a Monte Carlo method. And we multiplied a predefined energy weighting functions to the calculated energy spectra and integrated them in the whole energy range. For predefined energy weighting functions we selected five types of functions including the function which simulated the conventional data acquisition. The results of simulations showed that our proposed method could increase the low density contrast and reduce the beam-hardening effect