Systems and methods for obtaining two-dimensional images of an object, such as a patient, in multiple projection planes. In one aspect, the invention advantageously permits quasi-simultaneous image acquisition from multiple projection planes using a single radiation source.An imaging apparatus comprises a gantry having a central opening for positioning an object to be imaged, a source of radiation that is rotatable around the interior of the gantry ring and which is adapted to project radiation onto said object from a plurality of different projection angles; and a detector system adapted to detect the radiation at each projection angle to acquire object images from multiple projection planes in a quasi-simultaneous manner. The gantry can be a substantially “O-shaped” ring, with the source rotatable 360 degrees around the interior of the ring. The source can be an x-ray source, and the imaging apparatus can be used for medical x-ray imaging. The detector array can be a two-dimensional detector, preferably a digital detector.