A CT system includes a rotatable gantry having an opening for receiving an object to be scanned and an x-ray source coupled to the gantry and configured to project x-rays through the opening. The x-ray source includes a target, a first cathode configured to emit a first beam of electrons toward the target, a first gridding electrode coupled to the first cathode, a second cathode configured to emit a second beam of electrons toward the target, and a second gridding electrode coupled to the second cathode. The system includes a generator configured to energize the first cathode to a first kVp and to energize the second cathode to a second kVp, and a detector attached to the gantry and positioned to receive x-rays that pass through the opening. The system also includes a controller configured to apply a gridding voltage to the first gridding electrode to block emission of the first beam of electrons toward the target, apply the gridding voltage to the second gridding electrode to block emission of the second beam of electrons toward the target, and acquire dual energy imaging data from the detector.