Abstract: Aiming at the problem of projection simulation of 3D Shepp-I_ogan head phantom, this paper proposed a fast parallel method to calculate simulation projection. Firstly, the intersection points of 3D ray and each ellipsoid were calcu- lated in turn. Then, the sequence of intersection points was sorted, by which the region number of phantom and length of intersection between the ray and the region were determined. Finally,the projection of the ray was obtained by summing the projection of each region. On this basis,we decomposed the computing task into four independent subtasks and rea- lined fast parallel calculation of simulation projection of con}beam CT on multi-core platform by multi-thread tech- nictue. Experimental result shows that the proposed method is very effective, can get a speedup about 3. 5 times on ctuad cores platform. The accuracy of the projection data generated by the proposed method was verified by results of image reconstruction.

Key words: Con}beam CT，Shepp-Logan head phantom, Projection simulation, Multi-thread, Image reconstruction