A detector system for an x-ray imaging device includes a detector chassis, a plurality of sub-assemblies mounted to the detector chassis and within an interior housing of the chassis, the sub-assemblies defining a detector surface, where each sub-assembly includes a thermally-conductive support mounted to the detector chassis, a detector module having an array of x-ray sensitive detector elements mounted to a first surface of the support, an electronics board mounted to a second surface of the support opposite the first surface, at least one electrical connector that connects the detector module to the electronics board, where the electronics board provides power to the detector module and receives digital x-ray image data from the detector module via the at least one electrical connector. Further embodiments include x-ray imaging systems, external beam radiation treatment systems having an integrated x-ray imaging system, and methods therefor.
