A study on the artifacts generated by dental materials in PET/CT image.

PET/CT system reduces the scanning time and provides an anatomical image because it realizes a CT-based attenuation corrected image without using an isotope, such as 68 Ge or 137Cs, in the attenuation correcting method due to the recent technological development. On the other hand, artifacts are generated in a CT image by dental materials, which affect the attenuation corrected PET image. Against this backdrop, this study performed a clinical experiment and a phantom experiment. The clinical experiment targeted 40 patients without oral disease, including 20 patients who had metal prosthesis in their tooth and 20 patients who had a dental implant in tooth. In the phantom experiment, a dental cast was used for a PET/CT scan after the metal prosthesis and the dental implant was inserted in the original dental phantom to make a dental cast. According to the study results, when the patients had metal prosthesis, standard uptake value (SUV) decreased by approximately 19.6% in the dark streak artifact region and increased by approximately 90.1% in the bright streak artifact region, compared with the artifact free region. In the phantom with metal prosthesis, the SUV decreased by approximately 18.1% in the dark streak artifact region and increased by 18.0% in the bright streak artifact region, compared to the artifact free region. When the patients with dental implant, the SUV decreased by approximately 19.1% in the dark streak artifact region and increased by 96.6% in the bright streak artifact region, compared with the artifact free region. In the phantom with dental implant, the SUV decreased by approximately 14.4% in the dark streak artifact region and increased by 7.0% in the bright streak artifact region, compared to the artifact free region. Therefore, by considering these results, we can improve the diagnostic accuracy in oral and maxillofacial cancer.