A semi-automatic procedure for the evaluation of tooth cementum annulation images for paleodemographic studies
XIV, 201 pages. Freiburg, Albert-Ludwigs-Universität Freiburg (2007)
Tooth Cementum Annulation (TCA) images are microscopic images from the root of human teeth. These digital images display annual incremental lines which can be used for age estimation. Until now, the incremental lines (or tooth rings) have been counted manually from under the microscope or on the (digital) TCA image. Since research using the manual observations led to contradictory results, algorithms to automatically evaluate TCA images are considered a crucial step towards computer-assisted TCA age estimation.
TCA images can be evaluated based on measuring their features, but until now no statistical model was developed. In this work, TCA images are modeled as hidden Markov random fields, because these models can incorporate prior knowledge about tooth rings and are thereby able to imitate human vision. In particular, the Markov random field is specified by the FRAME model which incorporates filter responses to the label image into the Gibbsian distribution and is thus able to take into account long-range dependencies among the observed values and periodicity in the placement of tooth rings. The estimation of model parameters is rendered possible via an EM algorithm. This coherent approach is developed step-by-step and tested extensively throughout this work.