First steps toward automatic location of landmarks on X-ray images

We address the problem of locating some anatomical bone structures on lateral cranial X-ray images. These structures are landmarks used in orthodontic therapy. The main problem in this pattern recognition application is that the landmarks are difficult to distinguish on images even for the human expert, because of lateral projection of the X-ray process. We propose a 3 steps approach: the first step provides a statistical estimation of the landmarks, using an adaptive coordinates space; the second step computes a region of interest around the estimated landmark; and in the third step, each landmark is precisely located using its anatomical definition. This paper describes the two first generic steps and gives examples of the last step for two anatomical points.