近年來影像導引放射治療技術已被廣泛應用於治療不同位置的腫瘤組織，且其相關的研究在國際上也已被廣泛探討，然而評估HexaPOD自動追蹤對位治療床的殘餘誤差在文獻上並不多見，本研究的目的即在於分析HexaPOD治療床在修正pitch（±2°）、roll（±2°）與yaw（±1°）後的殘餘誤差。本研究使用Elekta Axesse型直線加速器搭配X光體積影像成像系統（ELEKTA XVI 4.2.1b47），並設計製作PMMA假體。實驗之前，須先將頭部假體置於PMMA假體上執行電腦斷層定位（GE Light-Speed四切電腦斷層掃描儀），切片厚度選擇2.50mm，待取得定位影像後，將影像輸出至ADAC治療計畫系統中，完成治療計畫製作後再輸入至XVI系統。研究結果發現，灰值影像比對的穩定度（再現性）優於骨影像比對，且就平移軸與旋轉軸而言，HexaPOD治療床修正單軸後的殘餘誤差（平均絕對誤差）為0.14mm與0.11度，略優於修正多軸後的0.21mm與0.16度。本研究創新之量測方法，除可提供臨床影像導引放射治療作為重要之參考指標，所得結果亦可驗證HexaPOD治療床修正誤差後的殘餘誤差可達毫米之內的等級。

Image-guided radiotherapy (IGRT) have increased dramatically in clinics for treating various tumors over the past several years. While the characteristics of IGRT in various applications have been widely investigated, residual error analysis of the HexaPODTM evo RT couch have so far remained quite limited. The aim of this study was to explore residual error of the HexaPODTM evo RT couch in pith, roll and yaw. The Elekta Axesse linac equipped with x-ray volume imaging system (ELEKTA XVI 4.2.1b47) was used for all irradiations. Measurements were made in a specially designed, PMMA phantom. To begin with, head phantom was scanned with a 4 slice GE Light-Speed CT simulator. A series of CT images were exported into ADAC Pinnacle version 8.0 TPS. Original plans were generated and then import into the XVI system. Our results found that the gray value match was more stable than the bone match. Residual errors (mean absolute error, MAE) in the translational axis were slightly smaller for single rotations compared to multiple rotations: 0.14 mm and 0.21 mm, respectively. Residual errors (MAE) in the rotational axis were slightly smaller for single rotations compared to multiple rotations: 0.11°and 0.16°, respectively. This work was confirmed that sub-millimeter residual error can be achieved using the HexaPODTM evo RT couch, and the novel method can be the important references indexes for clinic use.