A combined imaging apparatus for x-ray imaging of a subject in multiple modes has a supporting structure having an extended rotary arm, wherein the rotary arm has a computed tomography detector and a panoramic imaging detector, both mounted adjacently against a movable platen. A detector positioning apparatus is actuable to translate the position of the movable platen to either of at least first and second positions with respect to an x-ray source. The first position disposes the computed tomography detector in the direct path of an x-ray source and the second position disposes the panoramic imaging detector in the direct path of the x-ray source.