First of all, an imaging prototype was demonstrated based on a high-energy in-line phase contrast system prototype. The DQE of this system is calculated through modulation transfer function (MTF), noise power spectrum (NPS) and input signal to noise ratio under a fixed radiation dose. The radiation dose was estimated by employing a 4-cm-thick BR12 phantom. In this research, the x-ray exposure conditions were modified by not only using different tube voltage but also different prime beam filtration. Aluminum, Molybdenum, Rhodium, and a combined filter were selected to acquire a variety of x-ray energy compositions with 100, 110 and 120 kVp exposures. The resultant curves are compared through the modes of different kVp/same filter and different filter/same kVp.
As a result, the curves obtained under a fixed radiation dose, indicate that the MTF performs similar behavior under different experimental mode; the NPS is majorly affected by the composition of x-ray photon energies; and the overall DQE decreases with the increasing portion of high-energy x-ray photons in the exposure.