A method and apparatus for data conversion in an unequal γ angle CT system. The method for imaging in a CT system having a flat module detector array includes obtaining fan beam projection data of an object from a CT scan, obtaining a geometric structure parameter of the flat module detector array; rebinning data from the fan beam projection data to parallel beam projection data based on the geometric structure parameter to convert the fan beam projection data into the parallel beam projection data, and generating a CT image from the parallel beam projection data.