Fig.2 CT was performed with the following imaging parameters: 320-row detector; 120 kV; 200 mA; slice thickness, 0.5 mm; and pixel width, 0.3 mm. A calibration phantom containing three hydroxyapatite rods(0 mg/cm³, 100 mg/cm³, and 200 mg/cm³) was tested together with the specimen in water.