Simulation calculation of phantom projections based on physics model of medical X-ray imaging

In order to realistically simulate the projections of X-ray computed tomography (XCT), a projection simulation algorithm is presented by combining the X-ray energy spectrum distribution function with the tissue boundary approximation strategy. Firstly, the geometrical shapes and CT numbers of all sub-regions of a phantom are determined. Next, mapping these CT numbers onto corresponding tissue densities and elemental mass fraction, the tissue mass attenuation coefficients are calculated by XCOM software. Finally, the X-ray energy spectrum distribution function and projections that have been attenuated are computed according to the X-ray energy spectrum parameters, tissue densities, tissue mass attenuation coefficients and the distance between adjacent boundaries. This algorithm is simpler than analytic simulation programming, and needs lesser storage and has higher precision in contrast to the discrete simulation. The anticipated beam hardening effects are clearly shown after carrying out the 3-demension reconstruction of Feldkamp cone beam.