1. A method of reconstructing a tomography image, the method comprising: acquiring tomography data corresponding to a moving object by performing a tomography scan of the moving object; reconstructing, based on the tomography data, a plurality of prior images of the moving object respectively corresponding to a plurality of time points; generating first data by projecting a region of each of the plurality of prior images; reconstructing a first image based on the tomography data and the first data; generating second data by projecting a region of the first image; and reconstructing, based on the tomography data and the second data, a plurality of second images respectively corresponding to the plurality of time points.