Phase-contrast imaging uses the phase coefficient rather than the attenuation coefficient alone to image objects.
Consequently, it may resolve some structures that have similar attenuation coefficients but different phase coefficients
as their surroundings. Phase contrast imaging is also an edge-enhanced imaging technique. With this method, the
boundary of inside small structures could be easily determined. In this paper, the possibility of incorporating the phase
contrast in-line method into the current cone beam CT (CBCT) system was explored. Starting from the interference
formula of in-line holography, some mathematical assumptions were made and thus, the terms in the interference
formula could be approximately expressed as a line integral that is the requirement for all CBCT algorithms. So, the
CBCT reconstruction algorithms, such as the FDK algorithm could be applied for the in-line holographic projections,
with some mathematical imperfection. A point x-ray source and a high-resolution detector were assumed for computer
simulation. The reconstructions for cone-beam CT imaging were studied. The results showed that all the lesions in the
numerical phantom could be observed with an enhanced edge. However, due to the edge-enhancement nature of the inline
holographic projection, the reconstructed images had obvious streak artifacts and numerical errors. The image
quality could be improved by using a hamming window during the filtering process. In the presence of noise, the
reconstructions from the in-line holographic projections showed clearer edges than the normal CT reconstructions did.
Finally it was qualitatively illustrated that small cone angle and weak attenuation were preferred in this method.