1. A method performed by a processor of correcting detector misalignment effects in reconstructed images of an object from image data acquired by a medical imaging apparatus with rotating detectors, comprising: calculating via the processor misalignments of a detector corresponding to at least yaw and pitch of the detector with respect to a fixed coordinate system; and correcting said acquired image data based on said calculated misalignments; wherein the step of calculating comprises defining projection image coordinates [x′, y′] of a point object at [x, y, z] in said fixed coordinate system in terms of fixed misalignments.