A processor-implemented method of reconstructing image, comprising: accessing (S101, S201) a first set of projection data that comprises a plurality of first projection data each corresponding to a respective projection angle of a plurality of projection angles; generating (S102, S202) a first set of reconstructed data by image reconstruction with the first set of projection data; characterized in that, the method further comprises: generating (S103, S203) a second set of projection data by projection calculation according to the first set of reconstructed data, wherein the second set of projection data comprises a plurality of second projection data each corresponding to a respective projection angle of the plurality of projection angles; generating (S104, S204) a third set of projection data by shifting the first projection data corresponding to each of the plurality of projection angles with a shifting distance between the first projection data and the second projection data corresponding to each of the plurality of projection angles; and generating (S105, S205) a second set of reconstructed data by image reconstruction with the third set of projection data; wherein generating the third set of projection data comprises: constructing, for a projection angle, a cross-correlation function for first projection data and second projection data corresponding to the projection angle; determining the shifting distance between the first projection data and the second projection data corresponding to the projection angle according to a maximum value of the cross-correlation function; and obtaining projection data corresponding to the projection angle in the third set of projection data by shifting the first projection data corresponding to the projection angle with the shifting distance. accessing (S101, S201) a first set of projection data that comprises a plurality of first projection data each corresponding to a respective projection angle of a plurality of projection angles; generating (S102, S202) a first set of reconstructed data by image reconstruction with the first set of projection data; characterized in that, the method further comprises: generating (S103, S203) a second set of projection data by projection calculation according to the first set of reconstructed data, wherein the second set of projection data comprises a plurality of second projection data each corresponding to a respective projection angle of the plurality of projection angles; generating (S104, S204) a third set of projection data by shifting the first projection data corresponding to each of the plurality of projection angles with a shifting distance between the first projection data and the second projection data corresponding to each of the plurality of projection angles; and generating (S105, S205) a second set of reconstructed data by image reconstruction with the third set of projection data; wherein generating the third set of projection data comprises: constructing, for a projection angle, a cross-correlation function for first projection data and second projection data corresponding to the projection angle; determining the shifting distance between the first projection data and the second projection data corresponding to the projection angle according to a maximum value of the cross-correlation function; and obtaining projection data corresponding to the projection angle in the third set of projection data by shifting the first projection data corresponding to the projection angle with the shifting distance. constructing, for a projection angle, a cross-correlation function for first projection data and second projection data corresponding to the projection angle; determining the shifting distance between the first projection data and the second projection data corresponding to the projection angle according to a maximum value of the cross-correlation function; and obtaining projection data corresponding to the projection angle in the third set of projection data by shifting the first projection data corresponding to the projection angle with the shifting distance.