{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,14]],"date-time":"2026-06-14T23:12:59Z","timestamp":1781478779954,"version":"3.54.1"},"reference-count":47,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2023,1,23]],"date-time":"2023-01-23T00:00:00Z","timestamp":1674432000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Metal artifacts in dental computed tomography (CT) images, caused by highly X-ray absorbing objects, such as dental implants or crowns, often more severely compromise image readability than in medical CT images. Since lower tube voltages are used for dental CTs in spite of the more frequent presence of metallic objects in the patient, metal artifacts appear more severely in dental CT images, and the artifacts often persist even after metal artifact correction. The direct sinogram correction (DSC) method, which directly corrects the sinogram using the mapping function derived by minimizing the sinogram inconsistency, works well in the case of mild metal artifacts, but it often fails to correct severe metal artifacts. We propose a modified DSC method to reduce severe metal artifacts, and we have tested it on human dental images. We first segment the metallic objects in the CT image, and then we forward-project the segmented metal mask to identify the metal traces in the projection data with computing the metal path length for the rays penetrating the metal mask. In the sinogram correction with the DSC mapping function, we apply the weighting proportional to the metal path length. We have applied the proposed method to the phantom and patient images taken at the X-ray tube voltage of 90 kVp. We observed that the proposed method outperforms the original DSC method when metal artifacts were severe. However, we need further extensive studies to verify the proposed method for various CT scan conditions with many more patient images.<\/jats:p>","DOI":"10.3390\/s23031288","type":"journal-article","created":{"date-parts":[[2023,1,23]],"date-time":"2023-01-23T03:48:08Z","timestamp":1674445688000},"page":"1288","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Metal Artifact Reduction in Dental CBCT Images Using Direct Sinogram Correction Combined with Metal Path-Length Weighting"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7192-2641","authenticated-orcid":false,"given":"Mohamed A. A.","family":"Hegazy","sequence":"first","affiliation":[{"name":"R&D Center, Ray, Seongnam-si 13494, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Myung Hye","family":"Cho","sequence":"additional","affiliation":[{"name":"R&D Center, Ray, Seongnam-si 13494, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Min Hyoung","family":"Cho","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Kyung Hee University, Yongin-si 17104, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7573-2079","authenticated-orcid":false,"given":"Soo Yeol","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Kyung Hee University, Yongin-si 17104, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.cxom.2011.12.008","article-title":"A Comparison of Maxillofacial CBCT and Medical CT","volume":"20","author":"Angelopoulos","year":"2012","journal-title":"Atlas Oral Maxillofac. Surg. Clin."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"20190249","DOI":"10.1259\/dmfr.20190249","article-title":"3D-cinematic rendering for dental and maxillofacial imaging","volume":"49","author":"Stadlinger","year":"2020","journal-title":"Dentomaxillofac. Radiol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Cho, M.H., Hegazy, M.A.A., Cho, M.H., and Lee, S.Y. (2022). Cone-Beam Angle Dependency of 3D Models Computed from Cone-Beam CT Images. Sensors, 22.","DOI":"10.3390\/s22031253"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1109\/23.775600","article-title":"Metal streak artifacts in X-ray computed tomography: A simulation study","volume":"46","author":"Nuyts","year":"1999","journal-title":"IEEE Trans. Nucl. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1067\/j.cpradiol.2009.05.002","article-title":"A Review of Factors That Affect Artifact from Metallic Hardware on Multi-Row Detector Computed Tomography","volume":"39","author":"Kataoka","year":"2010","journal-title":"Curr. Probl. Diagn. Radiol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"229","DOI":"10.2217\/iim.12.13","article-title":"CT artifacts: Causes and reduction techniques","volume":"4","author":"Boas","year":"2012","journal-title":"Imaging Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5826","DOI":"10.1109\/ACCESS.2016.2608621","article-title":"Metal Artifact Reduction in CT: Where Are We After Four Decades?","volume":"4","author":"Gjesteby","year":"2016","journal-title":"IEEE Access"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"769","DOI":"10.1097\/01.rli.0000086495.96457.54","article-title":"A New Algorithm for Metal Artifact Reduction in Computed Tomography: In Vitro and in Vivo Evaluation after Total Hip Replacement","volume":"38","author":"Mahnken","year":"2003","journal-title":"Investig. Radiol."},{"key":"ref_9","first-page":"1913","article-title":"Streak artifact reduction in filtered backprojection using a level line-based interpolation method","volume":"41","author":"Bruyant","year":"2000","journal-title":"J. Nucl. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"576","DOI":"10.1148\/radiology.164.2.3602406","article-title":"Reduction of CT artifacts caused by metallic implants","volume":"164","author":"Kalender","year":"1987","journal-title":"Radiology"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"799","DOI":"10.1118\/1.595032","article-title":"An algorithm for the reduction of metal clip artifacts in CT reconstructions","volume":"8","author":"Glover","year":"1981","journal-title":"Med. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"6575","DOI":"10.1088\/0031-9155\/54\/21\/009","article-title":"A novel forward projection-based metal artifact reduction method for flat-detector computed tomography","volume":"54","author":"Prell","year":"2009","journal-title":"Phys. Med. Biol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1109\/TMI.2008.929103","article-title":"Suppression of Metal Artifacts in CT Using a Reconstruction Procedure That Combines MAP and Projection Completion","volume":"28","author":"Lemmens","year":"2008","journal-title":"IEEE Trans. Med. Imaging"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2852","DOI":"10.1118\/1.2218062","article-title":"Metal artifact reduction in CT using tissue-class modeling and adaptive prefiltering","volume":"33","author":"Bal","year":"2006","journal-title":"Med. Phys."},{"key":"ref_15","unstructured":"Jeong, K.Y., and Ra, J.B. (November, January 24). Metal artifact reduction based on sinogram correction in CT. Proceedings of the 2009 IEEE Nuclear Science Symposium Conference Record (NSS\/MIC), Orlando, FL, USA."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1007\/BF00169785","article-title":"A post-processing algorithm to reduce metallic clip artifacts in CT images","volume":"3","author":"Tuy","year":"1993","journal-title":"Eur. Radiol."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Meyer, E., Raupach, R., Schmidt, B., Mahnken, A.H., and Kachelriess, M. (2011, January 23\u201329). Adaptive normalized metal artifact reduction (ANMAR) in computed tomography. Proceedings of the 2011 IEEE Nuclear Science Symposium Conference Record, Valencia, Spain.","DOI":"10.1109\/NSSMIC.2011.6152691"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"5482","DOI":"10.1118\/1.3484090","article-title":"Normalized metal artifact reduction (NMAR) in computed tomography","volume":"37","author":"Meyer","year":"2010","journal-title":"Med. Phys."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1252","DOI":"10.1016\/j.acra.2011.05.009","article-title":"Monoenergetic Imaging of Dual-energy CT Reduces Artifacts from Implanted Metal Orthopedic Devices in Patients with Factures","volume":"18","author":"Zhou","year":"2011","journal-title":"Acad. Radiol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1097\/RLI.0b013e31824c86a3","article-title":"Metal Artifact Reduction by Dual-Energy Computed Tomography Using Energetic Extrapolation: A Systematically Optimized Protocol","volume":"47","author":"Meinel","year":"2012","journal-title":"Investig. Radiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1424","DOI":"10.1007\/s00330-011-2062-1","article-title":"Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation","volume":"21","author":"Bamberg","year":"2011","journal-title":"Eur. Radiol."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Hamelin, B., Goussard, Y., Gendron, D., Dussault, J.P., Cloutier, G., Beaudoin, G., and Soulez, G. (2008, January 14\u201317). Iterative CT Reconstruction of Real Data with Metal Artifact Reduction. Proceedings of the 2008 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, Paris, France.","DOI":"10.1109\/ISBI.2008.4541281"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"607","DOI":"10.1016\/S1076-6332(00)80576-0","article-title":"Fast iterative algorithm for metal artifact reduction in X-ray CT","volume":"7","author":"Wang","year":"2000","journal-title":"Acad. Radiol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1017\/S1431927699000057","article-title":"Iterative X-ray Cone-Beam Tomography for Metal Artifact Reduction and Local Region Reconstruction","volume":"5","author":"Wang","year":"1999","journal-title":"Microsc. Microanal."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"657","DOI":"10.1109\/42.538943","article-title":"Iterative deblurring for CT metal artifact reduction","volume":"15","author":"Wang","year":"1996","journal-title":"IEEE Trans. Med. Imaging"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1007\/s13534-019-00110-2","article-title":"U-Net Based Metal Segmentation on Projection Domain for Metal Artifact Reduction in Dental CT","volume":"9","author":"Hegazy","year":"2019","journal-title":"Biomed. Eng. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Zhu, Y., Liang, X., Deng, L., Zhang, C., Zhou, X., Xie, Y., and Zhang, H. (2021, January 12\u201314). CT Metal Artifact Correction Assisted by the Deep Learning-based Metal Segmentation on the Projection Domain. Proceedings of the 2021 IEEE International Conference on Medical Imaging Physics and Engineering (ICMIPE), Hefei, China.","DOI":"10.1109\/ICMIPE53131.2021.9698831"},{"key":"ref_28","first-page":"1","article-title":"Metal Artifact Reduction on Cervical CT Images by Deep Residual Learning 08 Information and Computing Sciences 0801 Artificial Intelligence and Image Processing","volume":"17","author":"Huang","year":"2018","journal-title":"Biomed. Eng. Online"},{"key":"ref_29","unstructured":"Wang, Z., Vandersteen, C., Demarcy, T., Gnansia, D., Raffaelli, C., Guevara, N., and Delingette, H. (2019). Medical Image Computing and Computer Assisted Intervention\u2014MICCAI 2019, Springer."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1370","DOI":"10.1109\/TMI.2018.2823083","article-title":"Convolutional Neural Network Based Metal Artifact Reduction in X-Ray Computed Tomography","volume":"37","author":"Zhang","year":"2018","journal-title":"IEEE Trans. Med. Imaging"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.2352\/ISSN.2470-1173.2018.15.COIMG-472","article-title":"Deep Learning Based Sinogram Correction for Metal Artifact Reduction","volume":"30","author":"Ghani","year":"2018","journal-title":"Electron. Imaging"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1109\/TCI.2019.2937221","article-title":"Fast Enhanced CT Metal Artifact Reduction Using Data Domain Deep Learning","volume":"6","author":"Ghani","year":"2020","journal-title":"IEEE Trans. Comput. Imaging"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Lin, W.A., Liao, H., Peng, C., Sun, X., Zhang, J., Luo, J., Chellappa, R., and Zhou, S.K. (2019, January 15\u201320). DuDoNet: Dual Domain Network for CT Metal Artifact Reduction. Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition, Long Beach, CA, USA.","DOI":"10.1109\/CVPR.2019.01076"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2803","DOI":"10.1088\/0031-9155\/57\/9\/2803","article-title":"CT metal artifact reduction method correcting for beam hardening and missing projections","volume":"57","author":"Verburg","year":"2012","journal-title":"Phys. Med. Biol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"794","DOI":"10.1118\/1.4903281","article-title":"Segmentation-free empirical beam hardening correction for CT","volume":"42","author":"Sawall","year":"2015","journal-title":"Med. Phys."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"128828","DOI":"10.1109\/ACCESS.2019.2939731","article-title":"A Direct Sinogram Correction Method to Reduce Metal-Related Beam-Hardening in Computed Tomography","volume":"7","author":"Lee","year":"2019","journal-title":"IEEE Access"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"225981","DOI":"10.1109\/ACCESS.2020.3044981","article-title":"A Two-Stage Approach for Beam Hardening Artifact Reduction in Low-Dose Dental CBCT","volume":"8","author":"Bayaraa","year":"2020","journal-title":"IEEE Access"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"216","DOI":"10.1016\/0020-0190(79)90072-3","article-title":"Another efficient algorithm for convex hulls in two dimensions","volume":"9","author":"Andrew","year":"1979","journal-title":"Inf. Process. Lett."},{"key":"ref_39","unstructured":"Chadnov, R.V., and Skvortsov, A.V. (July, January 26). Convex Hull Algorithms Review. Proceedings of the 8th Korea-Russia International Symposium on Science and Technology, KORUS 2004, Tomsk, Russia."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1016\/0020-0190(72)90045-2","article-title":"An Efficient Algorithm for Determining the Convex Hull of a Finite Planar Set","volume":"1","author":"Graham","year":"1972","journal-title":"Inf. Process. Lett."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"612","DOI":"10.1364\/JOSAA.1.000612","article-title":"Practical cone-beam algorithm","volume":"1","author":"Feldkamp","year":"1984","journal-title":"J. Opt. Soc. Am. A"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2258","DOI":"10.1118\/1.3130047","article-title":"Scatter correction for cone-beam CT in radiation therapy","volume":"36","author":"Zhu","year":"2009","journal-title":"Med. Phys."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Dunlap, J.C., Bodegom, E., and Widenhorn, R. (2010, January 17\u201321). Characterization and correction of dark current in compact consumer cameras. Proceedings of the Sensors, Cameras, and Systems for Industrial\/Scientific Applications XI, San Jose, CA, USA.","DOI":"10.1117\/12.840440"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"373","DOI":"10.1007\/s00411-010-0275-3","article-title":"Radiation damage in charge-coupled devices","volume":"49","author":"Bassler","year":"2010","journal-title":"Radiat. Environ. Biophys."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/srep03360","article-title":"Enhanced Detection Efficiency of Direct Conversion X-ray Detector Using Polyimide as Hole-Blocking Layer","volume":"3","author":"Abbaszadeh","year":"2013","journal-title":"Sci. Rep."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"6251","DOI":"10.1088\/0031-9155\/54\/20\/014","article-title":"The effects of field-of-view and patient size on CT numbers from cone-beam computed tomography","volume":"54","author":"Seet","year":"2009","journal-title":"Phys. Med. Biol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"183","DOI":"10.2214\/ajr.141.1.183","article-title":"Truncated-view artifacts: Clinical importance on CT","volume":"141","author":"Lehr","year":"1983","journal-title":"Am. J. Roentgenol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/3\/1288\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T18:13:56Z","timestamp":1760120036000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/3\/1288"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,1,23]]},"references-count":47,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2023,2]]}},"alternative-id":["s23031288"],"URL":"https:\/\/doi.org\/10.3390\/s23031288","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,1,23]]}}}