A method for reconstructing an image of an object utilizing a cone-beam volumetric computed tomographic imaging apparatus includes helically scanning the object with a radiation source utilizing the cone-beam volumetric computed tomographic imaging apparatus; selecting radiation beams emitted by the radiation source passing through a pixel P having a smallest cone angle in comparison with that of the conjugate rays of the radiation beam; and reconstructing an image of the object utilizing projection data obtained from the selected radiation beams while avoiding the use of redundant projection data from unselected conjugate rays of the selected radiation beams.