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Streak artefact correction of CT data by optical 3D imaging in the simulation of orthognathic surgery
International Congress Series 1281 (2005) 1418
Streak artefact correction of CT data by optical 3D imaging in the simulation of orthognathic surgery E. Nkenkea,T, S. Zachowb, M. Benzc, T. Maierc, M. Kramera, G. Ha¨uslerc, F.W. Neukama a
Department of Oral and Maxillofacial Surgery, University of Erlangen-Nuremberg, Germany b Department Visualization, Division Scientific Computing, Zuse Institute Berlin, Germany c Chair for Optics, University of Erlangen-Nuremberg, Germany
Keywords: Streak artifact; CT; Optical 3D image; Orthognathic surgery
1. Introduction Metal artefacts cause serious problems during virtual planning as they obscure dental arches in the CT scan. The simulation of postoperative dental occlusion is hindered because occlusal relief is not represented accurately. Therefore, it was the aim of the present study to introduce metal artifact correction in CT images by optical 3D images. 2. Methods 10 plaster casts of maxillary and mandibular dentition with inserted metal restorations were submitted to a 16-slice spiral CT. The volumetric data sets were postprocessed with the Amirak software to perform volume rendering and creation of isosurfaces. With an optical 3D sensor, threedimensional surface data of the plaster casts were acquired. The registration procedure of the different imaging modalities was carried out with the SLIM3D software. After completion of the registration, the number of corresponding points was counted and the mean distance between the data points of CT scan and optical scan was calculated for the assessment of the registration error. 3. Results From the plaster casts of the dentition with metal restorations, 6676.4 F 1417.9 sets of corresponding data points were used for the registration procedure (minimum 3932, maximum 9241). After the registration procedure, the mean distance between all sets of corresponding data points was 0.2671 F 0.0580 mm. The data ranged from 0.205 to .376 mm. 4. Conclusions The fusion of CT and optical 3D surface data improves the imaging of the dental arches’ virtual orthognathic surgery simulation. This technique helps to reduce the problem of metal artefacts in CT scans. However, the precision of the registration of CT scans with metal artefacts is still reduced compared to cases without artefacts. It seems that further development of CT scanners with higher resolution will not eliminate the problem of metal artefacts. Therefore, the image fusion technique should be established as a standard procedure in orthognathic surgery simulation. T Corresponding author. E-mail address: [email protected] (E. Nkenke). 0531-5131/ D 2005 CARS & Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2005.03.278
Streak artefact correction of CT data by optical 3D imaging in the simulation of orthognathic surgery E. Nkenkea,T, S. Zachowb, M. Benzc, T. Maierc, M. Kramera, G. Ha¨uslerc, F.W. Neukama a
Department of Oral and Maxillofacial Surgery, University of Erlangen-Nuremberg, Germany b Department Visualization, Division Scientific Computing, Zuse Institute Berlin, Germany c Chair for Optics, University of Erlangen-Nuremberg, Germany
Keywords: Streak artifact; CT; Optical 3D image; Orthognathic surgery
1. Introduction Metal artefacts cause serious problems during virtual planning as they obscure dental arches in the CT scan. The simulation of postoperative dental occlusion is hindered because occlusal relief is not represented accurately. Therefore, it was the aim of the present study to introduce metal artifact correction in CT images by optical 3D images. 2. Methods 10 plaster casts of maxillary and mandibular dentition with inserted metal restorations were submitted to a 16-slice spiral CT. The volumetric data sets were postprocessed with the Amirak software to perform volume rendering and creation of isosurfaces. With an optical 3D sensor, threedimensional surface data of the plaster casts were acquired. The registration procedure of the different imaging modalities was carried out with the SLIM3D software. After completion of the registration, the number of corresponding points was counted and the mean distance between the data points of CT scan and optical scan was calculated for the assessment of the registration error. 3. Results From the plaster casts of the dentition with metal restorations, 6676.4 F 1417.9 sets of corresponding data points were used for the registration procedure (minimum 3932, maximum 9241). After the registration procedure, the mean distance between all sets of corresponding data points was 0.2671 F 0.0580 mm. The data ranged from 0.205 to .376 mm. 4. Conclusions The fusion of CT and optical 3D surface data improves the imaging of the dental arches’ virtual orthognathic surgery simulation. This technique helps to reduce the problem of metal artefacts in CT scans. However, the precision of the registration of CT scans with metal artefacts is still reduced compared to cases without artefacts. It seems that further development of CT scanners with higher resolution will not eliminate the problem of metal artefacts. Therefore, the image fusion technique should be established as a standard procedure in orthognathic surgery simulation. T Corresponding author. E-mail address: [email protected] (E. Nkenke). 0531-5131/ D 2005 CARS & Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2005.03.278