臺灣博碩士論文加值系統

　　牙科錐束斷層掃描設備(Dental cone beam computed tomography, Dental CBCT)已廣泛地使用在植牙的手術規劃相關治療領域。當病患齒槽有植入金屬物質時，這些高原子序數物質將造成該物質四周的CT值的錯誤，統稱金屬偽影(Metal artifact)。這些錯誤的CT值可能導致醫生判讀的不正確。本研究之目的是比較由台灣騰協(Taiwan CareTech Corporation)所發展的Dental CBCT設備與德國(KaVo Dental GmbH)的Dental CBCT分析金屬偽影抑制後的圖像。設計8組不同植牙狀況下，經偽影抑制的CT圖像，分析不同之鈦金屬與鎳鉻合金植入物材料所造成的CT值(CT number)準確度與相對應的標準差(Standard deviation)的差異。其研究結果顯示，在金屬植入物周圍影響圖像判讀的條紋偽影(Streaks)程度KaVo 3D eXam較DCT 100低，DCT 100的整張圖像有亮紋分佈。鎳鉻合金植入物的圖像品質較鈦金屬植入物低。當前排牙齒有金屬植入物時，材料型態為鎳鉻合金牙齒橋，圖像品質是8組牙齒模型中最差的。在CT值的差異分析中，植入物是鈦時，KaVo 3D eXam的圖像在14組VOI區域較DCT 100小1/3倍，品質較佳。金屬植入物是鎳鉻合金時，VOI區域內CT值的差異，DCT 100與KaVo 3D eXam雷同。在標準差分析中得知，14個VOIs中，此2台CBCT的標準差相似，但KaVo 3D eXam所得的14個VOIs彼此間標準差的差異較小。由上述顯示，DCT 100的CT值準確度不比KaVo 3D eXam差，但KaVo 3D eXam在14個VOIs區中彼此的標準差的變異較小，圖像中條紋偽影的程度低，因此圖像觀測的感覺較佳。

Dental cone beam computed tomography (CBCT) is an important tool for dentists in diagnosis of lesions and treatment planning. Metallic implants cause metal artifacts in CT images. Metal artifact reduction (MAR) algorithms are necessary in commercial CBCT equipment. We performed a dental impression study with seven factors including material and positions of dental prostheses. The CT number accuracy and standard deviation of 14 regions of interest (ROIs) based on MAR corrected images obtained by DCT 100 (Taiwan CareTech Corporation) and KaVo 3D eXam (KaVo Dental GmbH) was compared. For titanium (Ti) prostheses, except for the condition of posterior bridge, the performance of the DCT 100 is 1.2 times better than the KaVo 3D eXam. With nickel-chromium alloy (Ni-Cr alloy) prostheses, the CT number accuracy of the DCT 100 and the KaVo 3D eXam are comparable. The CT number accuracy is the worst with Ni-Cr anterior bridges. In the case of dental impressions with posterior prostheses, although CT accuracy of DCT 100 is indeed comparable to KaVo 3D eXam, standard deviations of ROI next to prostheses obtained by KaVo 3D eXam are more uniform and smaller than obtained by DCT 100. The contrast of ROI next to prostheses is better.

摘要 I
ABSTRACT III
表目錄 VII
圖目錄 VIII
第一章　緒論 1
第一節　研究動機 1
第二節　研究目的 3
第二章　文獻探討 4
第一節　偽影形態 4
一、雜訊(Noise) 4
二、環狀偽影(Ring artifact) 5
三、光束硬化與散射(Beam hardening and scatter) 8
四、金屬偽影(Metal artifact) 9
五、移動偽影(Motion artifact) 9
第二節　金屬材質關係 14
第三節　圖像分析方法 15
第三章　研究方法 19
第一節　因子設計和牙齒模型製作 19
一、因子設計 19
二、牙齒模型製作 22
第二節　斷層掃描設備和圖像分析 28
一、斷層掃描設備 28
二、圖像分析 32
第四章　結果 34
第一節　圖像分析結果 34
一、CT值的差異 34
(一) DCT 100 34
(二) KaVo 3D eXam 34
二、雜訊值的差異 35
(一) DCT 100 35
(二) KaVo 3D eXam 35
第二節　統計分析與結果 62
一、因子與水準 62
二、信號雜訊比與變異數分析 63
(一) 各因子水準分析 63
(二) 因子對於CT值的雜訊的貢獻 63
第五章　討論與結論 71
第一節　因子對CT值準確度的效果 71
第二節　因子對CT值雜訊程度的效果 71
文獻參考 73

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