Disclosed systems and methods may include an imaging system. The imaging system may include a 4D-CBCT apparatus able to generate a plurality of CBCT images corresponding to different temporal phases. The imaging system may also include a radiographic apparatus able to generate a radiograph. Further, the imaging system may include a synchronization device for correlating a radiograph of said radiographic apparatus with a CBCT image generated by said 4D-CBCT apparatus, such that a reference radiograph can be determined.