1. A computed tomography (CT) system, comprising: an x-ray source and x-ray detectors configured to rotate within a scanned plane around an object, the detector obtaining attenuation measurements from the object as the object is moved in a Z-direction through the scanned plane; a computer module identifying first and second portions of a region of interest (ROI) in the object, the second portion including an organ of interest (OOI) within the ROI, the first region differing from the second region; an x-ray controller providing a first tube current to drive the x-ray source when scanning the first region and providing a different second tube current to drive the x-ray source when scanning the second region.