A gantry of a combined tomography scanner including an annular outer support, an annular drum concentrically positioned within the outer support rotatable about a rotation axis of the drum, and an annular disk extending radially inwardly from an inner circumferential surface of the drum. At least one of the disk and the drum include structural members for receiving and supporting tomography scanning components on opposing first and second sides of the disk. Among other features and benefits, the gantry can be used for a combined tomography scanner system, e.g., combining an x-ray CT scanner and a PET scanner in a single machine.