利用田口最佳法評量錐形射束（CBCT）的影像品質條件

現今放射治療領域中的錐形射束電腦斷層（Cone-Beam CT）影像已經成為不可或缺的工具，影像品質及相關劑量越來越受重視，因此本研究的目的是利用田口方法最佳化評量錐形射束電腦斷層影像品質條件所需的最適條件，使用Catphan 504假體並量測其鐵氟龍（Teflon）及壓克力（Acrylic）的對比雜訊比，類似骨頭與軟組織的HU比值，雜訊比越高越好，找出最佳化參數組合後再量測其劑量輸出量及是否因條件改變而影響自動對位的結果。由變異分析及驗證實驗結果，顯示最佳化參數組合是照野大小（FOV）為27.2 x 20.6，管電流*秒（mAs）為20 x 10，投射量數目（No. of Projection）為720，像素數目（No. of pixel）為256 x 256，切片厚度（Slice thickness）為3，重組濾片（Reconstruction filter）為平滑，圓圈假影消除（Ring Artifact Suppression）為弱。本研究運用田口方法，不僅可節省實驗耗費時間及次數，又可達到設定的結果，並發現調整投射量及影像後處理的功能來加強骨頭與組織影像對比雜訊比，比起原廠給的條件，可以降低病人的劑量，不影響自動對位系統的效果，達到所需的影像品質。

關鍵字

錐形射束電腦斷層；田口方法；影像品質

並列摘要

CBCT images become more and more essential technique in Radiation oncology. Image quality and relative dose of CBCT had been more and more concerned. This study used Taguchi method to optimize the operative parameters in CBCT to reach better image from practical viewpoint. The Catphan 504 phantom was adopted in this work because of either Teflon or Acrylic had similar HU response to bone and tissue in the real examination and a higher CNR was the optimized recommendation. The recommended combination of CBCT operative parameters was further verified by inspecting the accompanied exposed dose to comply with the ALARA principle. The optimized parameters setting were FOV for 27.2*20.6, mAs for 20*10, No. of Projection for 720, No. of pixel for 256*256, Slice thickness for 3, Reconstruction filter for smooth and Ring Artifact Suppression for weak and were verified from the ANOVA test in this work. The optimal setting had superior either CNR or lower dose to original one. Using Taguchi method not only minimized the experimental frequencies but also lowered the exposed dose in real examination process.

並列關鍵字

CBCT ； Taguchi method ； Image quality

國際替代計量

利用田口最佳法評量錐形射束（CBCT）的影像品質條件

全文下載

主題瀏覽