title: Content-based access to oral and maxillofacial radiographs.
abstract: OBJECTIVE
  Content-based access (CBA) to medical image archives, i.e. data retrieval by means of image-based numerical features computed automatically, has capabilities to improve diagnostics, research and education. In this study, the applicability of CBA methods in dentomaxillofacial radiology is evaluated.
  
  
  METHODS
  Recent research has discovered numerical features that were successfully applied for an automatic categorization of radiographs. In our experiments, oral and maxillofacial radiographs were obtained from the day-to-day routine of a university hospital and labelled by an experienced dental radiologist regarding the technique and direction of imaging, as well as the displayed anatomy and biosystem. In total, 2000 radiographs of 71 classes with at least 10 samples per class were analysed. A combination of co-occurrence-based texture features and correlation-based similarity measures was used in leaving-one-out experiments for automatic classification. The impact of automatic detection and separation of multi-field images and automatic separability of biosystems were analysed.
  
  
  RESULTS
  Automatic categorization yielded error rates of 23.20%, 7.95% and 4.40% with respect to a correct match within the first, fifth and tenth best returns. These figures improved to 23.05%, 7.00%, 4.20%, and 20.05%, 5.65% and 3.25% if automatic decomposition was applied and the classifier was optimized to the dentomaxillofacial imagery, respectively. The dentulous and implant systems were difficult to distinguish. Experiments on non-dental radiographs (10,000 images of 57 classes) yielded 12.6%, 5.6% and 3.6%.
  
  
  CONCLUSIONS
  Using the same numerical features as in medical radiology, oral and maxillofacial radiographs can be reliably indexed by global texture features for CBA and data mining.
authors: Department of Medical Informatics, Aachen University of Technology (RWTH), Aachen, Germany. deserno@ieee.org.
authors: T M
authors: TM
authors: Deserno
authors: B
authors: B
authors: Molander
authors: M O
authors: MO
authors: Güld
authors: C
authors: C
authors: Thies
authors: H-G
authors: HG
authors: Gröndahl
mesh_terms: D003628:Database Management Systems; D048048:Dental Informatics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016247:Information Storage and Retrieval; D008492:Medical Informatics Computing; D010363:Pattern Recognition, Automated; D011861:Radiography, Dental / Q000145:classification; D019252:Radiography, Dental, Digital / Q000145:classification; D011862:Radiography, Panoramic / Q000145:classification; D011873:Radiology Information Systems / Q000458:organization & administration*