1. A method of bone registration of quantitative computed tomography (CT) images, comprising acquiring data of a baseline CT scan and a follow-up CT scan of a bone in an individual to produce a baseline image and a follow-up image, segmenting a bony structure of the image via an approach that can determine thresholds for separating the bony structure from background and non-skeletal tissues, and registering a bone surface of the follow-up image with a bone surface in the baseline image using a 3D registration algorithm, whereby an overlap of the follow-up bone surface and the baseline bone surface is better than that before the registration, wherein, the follow-up bone surface and the baseline bone surface are aligned.