Compared with conventional X-ray, the cross-sectional images obtained by CT have accurate layer thickness, clear image, high density resolution, and no interference from structures outside the plane. In addition, the cross-sectional images obtained from CT scans can be reorganized and reconstructed by computer software processing to obtain cross-sectional images in multiple planes such as sagittal and coronal positions required for diagnosis. Quantitative analysis can also be done according to the X-ray attenuation coefficient of the tissue, and specific CT values can be measured for quantitative analysis.