Title: 3D cephalometry: a new approach for landmark identification and image orientation
Abstract: In orthodontics and craniofacial surgery, cephalometric analysis is an important tool for diagnosis and treatment planning as well as outcome evaluation. Because of the need to study complex abnormal anatomies such as asymmetrical cases, interest for three-dimensional computed tomography (3D CT) cephalometry has risen over the last two decades. The most common way to identify landmarks on 3D surface renderings is manual point-picking. Orientation of the skull can be done either by manual (subjective) alignment of anatomic structures or by automatic set-up of a reference system based on previously determined landmarks. In this study, we propose a new method for 3D CT cephalometric analysis. Anatomic landmarks are identified by calculation after landmark-region-picking rather than by point-picking the landmark itself. The surface region is picked on a triangular mesh created from CT images. Depending on the landmark definition, it will be refined to a line region. Landmark calculation is done by calculating the extreme point in a specified direction of the region, according to the landmark definition and taking into account interpolation between mesh vertices. Because the region-picking operation is less user-dependent, this approach should result in higher intra- and inter-observer reproducibility. Furthermore, an iterative procedure is used to orientate the skull in a standardized way, based on four landmarks. During each iteration the skull is re-orientated and the appropriate landmarks are recalculated until all orientation requirements are fulfilled. Small changes in landmark coordinates, caused by rotating the model and resulting in unsatisfied orientation requirements, will therefore be eliminated, improving the accuracy of image orientation and landmark determination. Moreover, this standardized orientation method should allow accurate comparison of pre- and postoperative data. In future, reproducibility tests will be performed to validate the new approach.
Publication Year: 2009
Publication Date: 2009-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
Access and Citation
Cited By Count: 3
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