Cone beam computed tomography(CT) based on flat detector has interested many CT researchers.Different CT scanning modes have different effect on ART image reconstruction.In this paper

using a 128 ? 128 ?128 3D Shepp-Logan head model as the object of simulation

impacts on image reconstruction are studied with different geometries of the radiation source

scanning center and detectors;different number of projections;and different scanning modes under fixed projections.An object to which scans cannot be done at certain angles is investigated

too.The following results are obtained.The image reconstruction is better when the source-center and the center-detector distances are in a certain proportion.Under fixed projections

the reconstructed image quality is better with a uniform 180o scan.To obtain a better image reconstruction in occasions where some angles are unable to scan

the projections should fill the first interval angle range uniformly with the angle interval 1°–2°

and the remaining projections should fill the second interval angle range uniformly.