An image processing method provides a step of detecting the pedicle region of vertebral arch detects the region having the higher pixel value compared to the periphery thereof is detected by classifying three classes ABC (detection of the pedicle of vertebral arch) of the step S2. Then, in the case of a failure to detect the intervertebral region, e.g., when the intervertebral region is crushed, the boundary, contacting to the cervical vertebra side of the pedicle of vertebral arch detected by the step of classifying three classes ABC (detecting the pedicle of vertebral arch) described above is drawn by classifying ABC three classes (drawing the boundary) of the step S2. Accordingly, even when the intervertebral region is crushed or when the intervertebral region is undetectable, the boundary between the vertebral bodies can be detected accurately. Therefore, the detection performance of the correct boundary is enhanced so that it can also be effective on that the manual correction frequency by the user decreases and the throughput increases.
