The forward projection of cone-beam CT image reconstruction algorithms requires both excessive computation and time consuming.A novel CT forward projection method based on graphics processing unit is proposed for accelerating the forward projection calculation.The method achieves the forward projection calculation in circular cone-beam scanning mode by using texture mapping techniques in GPU programmable pipeline.Because projections are calculated slice by slice in parallel

this method has the advantages of higher computational efficiency and calculation at full floating point precision.Three optimization methods are also presented for further improving the execution efficiency of the method.The advantages of this method are verified by the experiments of the projection calculation of Shepp-logan phantom and 3D image reconstruction with iterative image reconstruction algorithm.