Metal Artifact Reduction in Cone-beam Computed Tomography
| Autor: | Wan-Ting Lee, 李婉婷 |
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| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 Background: While clinical applications of CBCT have expanded, current CBCT technology has limitations due to the streak artifacts caused by metallic objects. The aim of present study was to develop an effective procedure which reduce the streak artifacts and improve the diagnostic value of the CBCT images on vertical root fractures. Methods: We designed five physical phantoms to simulate teeth with metal post insertion and vertical root fracture. Owing to the variable direction of vertical fracture lines, different angle of intersecting fracture lines were designed for different phantoms. Four metal artifacts reduction methods by manipulating projection data were developed. In methods 1~3, analytical reconstructions were applied. Then the method 1, which had the best performance, was chosen for further iterative reconstruction, and it was so-called method 4. The performance was evaluated by comparing the difference of root mean square (RMS) and uniformity before and after metal artifacts reduction. Results: All the metal artifacts were reduced effectively. In the quantitative evaluation, metal artifacts reduction using method 4 had the best performance in reducing streak artifacts. But due to the fine vertical fracture lines of human tooth used in this study, the fracture lines canno’t be clearly detected after metal artifact reduction. It needs further study when these methods are applied on teeth with fine vertical root fractures. Conclusion: This study indicates that metal artifacts can be reduced effectively by manipulating projection data. Performance of different methods can be evaluated based on objective data provided by the dental phantom models. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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