1. A method of operating tomographic imaging systems that each include a source and a detector, the method comprising: capturing a plurality of first projection images of a first patient using the source and detector of a first imaging system at a first orientation of the source and detector; after the step of capturing, performing a calibration scan of a calibration object using the source and detector of the first imaging system to generate first geometric calibration data corresponding to the first orientation; capturing a plurality of second projection images of a second patient using the source and detector of a second imaging system at an orientation similar to the first orientation within a predetermined deviation; and reconstructing a three dimensional image of the second patient using the captured plurality of the second projection images and the generated first geometric calibration data corresponding to the first orientation.