Computed tomographyにおけるcalibration field of viewやdisplay field of viewが及ぼす金属アーチファクト低減効果の影響

摘要

Purpose: The purpose of this study was to investigate the effects of the metal artifact reduction using single energy metal artifact reduction (SEMAR) with a prosthetic hip joint in different field of view (FOV). Methods: A prosthetic hip joint was arranged at the center of the phantom. The phantom images were scanned by changing calibrated-FOV(C-FOV) of 240,320,400, and 500 mm. Those images were reconstructed by changing the display-FOV(D-FOV) of 120,180,240, and 320 mm. The metal artifact reduction with the SEMAR was evaluated by calculating the artifact index (AI) and its decrease ratio. Results: The AI of C-FOV(500 mm) and D-FOV(120,180,240, or 320 mm) were 15.8,15.8,15.7, and 14.4 with SEMAR. For changed C-FOV, the AI of C-FOV(240 mm) was significantly higher than any other C-FOVs. The AI of C-FOV(240 mm) was 29.8-30.0 and that of the other C-FOV were 12.4-15.8 with SEMAR. In addition, the decrease ratio of AI was 52.2-54.1% for C-FOV(240 mm) and 58.9-73.2% for the other C-FOVs. Conclusion: Although the SEMAR decreased the metal artifact, the effect of reducing the metal artifact was affected by C-FOV.%人工股関節形成術は，股関節の変形性関節症を治療するために行われ，主に金属製の人工骨頭へ置換される.人工股関節形成術後は，computed tomography (CT)検査が用いられ，骨と人工骨頭の癒着や緩みなどの有無について評価される.しかし，その評価は人工骨頭から発生する金属アーチファクトにより難しくなるとされている.