State of the Art of Fusion of Computed Tomography Data and Optical 3D Images

When three-dimensional imaging is necessary in dentistry, oral surgery or maxillofacial surgery, conventional computed tomography or cone beam computed tomography is chosen regularly. However, there are two obvious drawbacks. Metallic restorations lead to pronounced streak artefacts in conventional computed tomography. Moreover, the resolution of both conventional computed tomography and cone beam computed tomography is limited to 0.3 mm. This resolution is not sufficient for the fabrication of dental restorations. In order to improve the quality of the two different computed tomography techniques and to eliminate streak artefacts, fusion with optical 3D images can be considered. The resolution of optical 3D images can reach the range of some µms depending on the calibration of the sensor. Metal artefacts do not occur. The fusion of computed tomography images without artefacts and optical 3D images leads to a mean deviation of corresponding points for the two imaging techniques of 0.1262 ± 0.0301 mm. When computed tomography images with metal artefacts are used, the deviation increases up to 0.2671 ± 0.0580 mm. The accuracy of image fusion is significantly reduced by metal artefacts (p 0.0005). When image fusion of computed tomography and optical 3D images is used in clinical studies, the mean deviation of corresponding points for the two imaging techniques for mandible and maxilla is 0.66 ± 0.49 mm and 0.56 ± 0.48 mm, respectively. The available data on image fusion show that the quality of computed tomography data without streak artefacts can be significantly improved by registration with optical 3D images. The precision of the fused images exceeds the resolution of the original computed tomography. When streak artefacts are present, image fusion makes it possible to increase the quality of the data to the level of the original resolution of computed tomography without artefacts. Keywords: computed tomography, cone beam computed tomography, optical 3D image, triangulation, registration, fusion of image data