Volumetric bone mineral density (vBMD) measurement in the trabecular and cortical bone compartments of Th12 vertebrae using quantitative computed tomography (QCT) method and Osteo CT application package (Software Version B10/2004A), and expressed quantitatively as calcium hydroxyapatite (Ca-HA) density in the trabecular (TbCa-HA) and cortical bone (CbCa-HA). CT: the self-name of the software.