1. A CT system comprising: a rotatable gantry having an opening to receive a patient to be scanned; a high frequency electromagnetic energy projection source configured to project a high frequency electromagnetic energy beam toward the object; a detector array configured to detect high frequency electromagnetic energy passing through the patient; a data acquisition system (DAS) connected to the detector array and configured to receive imaging data therefrom, the imaging data being free of a bone mineral density (BMD) reference phantom; and a computer programmed to: calculate a patient image attenuation area (IAA) from the CT imaging data; compare the patient IAA to a plurality of BMD reference values and a plurality of reference IAAs; and determine a patient BMD value based on the comparison of the patient IAA to the plurality of BMD reference values and the plurality of reference IAAs.