應用田口方法對錐狀射束電腦斷層掃描肝臟影像品質之最佳化

Optimizing the CBCT Image Quality of Liver Using Taguchi Analysis and a Revised Line-pair Phantom

周怡君(YI-CHUN CHOU)

指導教授 ： 潘榕光

中臺科技大學/健康科學院/醫學影像暨放射科學系暨研究所/碩士(2018年)

摘要

當利用錐狀射束電腦斷層對腫瘤位於胸、腹部的執行影像擷取時，往往會因為體內器官移動，特別是呼吸，而造成假影，例如模糊、條狀假影以及影像失真。假影不但會降低影像品質，也可能影響治療位置比對的準確性。本研究旨在運用田口分析法找出錐狀射束電腦斷層最佳化掃描條件以改善影像品質與穩健性。本研究將自製線對假體為60×30×20 mm3的壓克力長方體固定在擬人肝腎壓克力假體中以模擬人體腹部使用錐狀射束電腦斷層產生放射治療前即時影像的狀態，探討參數條件為管電壓、管電流、擷取角度、濾片。
將四項控制因子條件帶入田口直交表歸納成8組(L8)的實驗條件: （A）管電壓: 110kV、130 kV；(B)管電流: 10mA、32mA；(C)擷取角度:掃描300°收集影像與掃描360°收集影像；(D)濾片的使用與否:F0為無使用、F1是有使用濾片。
結果顯示，管電壓為130 kV、管電流為32 mA、擷取角度360度、有使用濾片為最佳化參數條件，其組合影像品質與再現性都較原廠條件佳；而管電壓與濾片具有強交互作用，其次是管電壓與管電流的交互作用；此外，使用變異數分析驗證發現，管電流、擷取角度、濾片皆對影像品質有顯著性影響。然而，本研究僅找到最好的結果，故探討潛在因素做為日後相關研究之參考，以期能有更好的錐狀射束電腦斷層掃描影像品質。錐狀射束電腦斷層的影像，若能提高影像品質，可讓醫師在不做其他檢查狀況下，更能善用即時影像掌握患者身體狀況。

關鍵字

田口分析法 ； 錐狀射束電腦斷層 ； 自製線對假體

並列摘要

While capturing images of the tumors in the chest or abdomen with cone beam computed tomography (CBCT), artifacts are often produced by organ movement, especially by respiration; for instance, blurring, streaking artifacts, and distortion. The artifacts may not only lower the image quality but affect the accuracy of comparing the treatment positions. This study aimed to explore the optimal scanning condition of CBCT image quality and robustness. In the research, a 60×30×20 mm3 acrylic homemade line group phantom was fixed in an acrylic anthropomorphic phantom to mimic the CBCT real-time image of the patient’s abdomen before the radiation therapy, and tube voltage, tube current, acquisition angle as well as filter were four parameters to be investigated.
The four control factor conditions in Taguchis’s Orthogonal Arrays, forming a 2-Level Experiments with L8 are: (A) tube voltage: 110kV、130 kV; (B) tube electric current: 10mA、32mA; (C) acquisition angle: 300° acquisition angle 、360° acquisition angle; (D) with or without a filter: F0, without a filter; F1, with a filter.
The findings of this study indicated that under the setting of 130 kV, 32 mA, 360° acquisition angle, and with a filter, the image quality and the reproducibility were better than those of the original grant condition. After conducting the analysis of variance (ANOVA), the data displayed that tube voltage, tube current, acquisition angle, and filter had a significant effect on image quality. Moreover, there was a strong interaction between tube voltage and filter, followed by that between tube voltage and tube current. The result in this study was only a relatively good condition, therefore, the potential factors discussed in this study are expected to be taken as references for future studies and create better CBCT image quality. If the CBCT qulaity can be improved, the doctors will be able to grasp the body condition of patients through the real-time images without conducting other examinations.

並列關鍵字

Taguchi Analysis ； Cone Beam Computed Tomography ； Homemade Line Group Phantom

參考文獻

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