Publication Details

Proceedings First Annual Symposium of the IEEE/EMBS Benelux Chapter

Contribution To Book Anthology


Although in recent years the use of digital subtraction radiography (DSR) has steadily increased in general medicine, dental caries diagnosis seems to be largely deprived of the recent developments in this field. This is quite remarkable since the clinical assessment of incipient caries could greatly benefit from the improved capability of DSR to reveal subtle changes in mineralization. One obstacle for the embracing of DSR might be the difficult problem of preserving a constant exposure geometry between successive intraoral radiographic exposures. Even the slightest misalignment, combined with the sharp density contrast at the caries initiation sites, may cause artifacts that can mimic or conceal true changes in radiolucency. However, another fundamental obstacle resides in the nature of the methods which are currently used for the retrospective geometric standardization of intraoral radiographs acquired with nonconsistent exposure geometry. These methods largely depend on the manual assignment of corresponding features between pairs of images which renders them quite sensitive to the user precision and dexterity. It is rather doubtful that procedures depending on such an extensive user involvement will ever find widespread acceptance as a clinical tool for the diagnosis of caries. We are disclosing in this article result of an ongoing study in which the prospects for a fully automated application of DSR in dental caries diagnosis are explored. In this study we compared an advanced method, based on the concept of Mutual Information (MI), with a more conventional pyramidal edge-based registration method. The performance of the MI-based method was found to degrade less rapidly under increasing angular disparity.