An apparatus for computed tomography imaging of a patient has a rotatable mount that is actuable to rotate about a rotation axis and that supports, at opposite ends an x-ray source and an x-ray detector, wherein the x-ray source is disposed to direct a radiation beam through the patient and toward the detector. A patient positioning apparatus positions the patient relative to the rotation axis. A control logic processor controls rotation of the rotatable mount and acquires image data for the patient at each of a number of angular positions about the rotation axis. A collimator is disposed in front of the x-ray source and controlled by the control logic processor to center the radiation beam, at each of the plurality of angular positions, on a region of interest that is spaced apart from the rotation axis.
