A radiation imaging device includes a detector capable of detecting radiation from either a KV source or an MV source. The detector includes a photodetector assembly, a scintillator adjacent to a first side of the photodetector, and a metal plate adjacent to a second side of the photodetector. The detector may also include a second scintillator. The first side of the photodetector assembly is positioned toward the KV source for KV imaging, while the second side is positioned toward the MV source for MV imaging. The radiation imaging device includes a first gantry for the MV source and a second gantry for the detector. The KV source may be supported by either the first gantry or the second gantry. The second gantry includes a robotic arm for positioning the detector for imaging, and is configured for moving the detector (and the KV source) out of the MV beam.