- 期刊
利用不同放射治療計劃系統分析掃描參數造成螺旋狀電腦斷層掃描之體積重組誤差的因素
The Analysis of Confounding Factors in Volume Reconstruction with Spiral Mode CT Simulation in Different Treatment Planning System
摘要
本研究是要探討評估螺旋狀電腦斷層掃描儀，在不同的治療計劃系統中造成重組體積誤差的因素。我們將假體在不同的電腦斷層掃瞄條件下逐一進行掃描，並將得到的影像資訊分別傳輸至不同治療計劃系統，驗證不同的治療計劃系統其重組出來的體積是否相同。在實驗中我們使用的電腦斷層掃描儀為GE LIGHTSPEED RT16，假體形狀為球體，其中球體直徑分別為20 mm、50 mm、100 mm三種，實驗所使用的治療計劃系統有三種：（一）搭配GE電腦斷層掃描儀所使用的Advanced Workstation（AW）軟體；（二）BrainLab公司所出的iPLAN軟體；（三）Philip公司所生產的Pinnacle軟體。研究結果可以發現真正影響到重組體積誤差的掃描條件為切面厚度和掃描物體的體積大小，切片重疊因子和治療計劃系統的不同對於重組體積的影響並不明顯，我們發現在三種治療計劃系統裡體積較大的假體不管使用何種切面厚度或切片重疊因子其重組體積的誤差大都在3%上下，但在體積小的假體時其重組體積不管在使用何種切面厚度或切片重疊因子其誤差都較大，如果使用的切面厚度為5 mm時，誤差甚至可以高達12%，因此我們發現在體積較小的掃描物體時使用較大的切片厚度，會使其重組體積產生較大誤差。而在不同的治療計劃系統中，每套治療計劃系統所描繪和讀取出來的假體體積彼此間雖然有差異但並不明顯，而造成不同治療計劃系統所評估出來的體積差異，主要是因為在物體邊緣的部分體積效應所造成的HU值判斷上的誤差。
並列摘要
The aim in this study is to investigate and evaluate the error factors used by volume reconstruction of spiral computed tomography (CT, GE LIGHTSPEED RT16) in different treatment planning system (TPS). Sphere phantoms were used with different diameters 20 mm, 50 mm, and 100 mm, respectively. In order to verify the reconstruction volume, CT scan images were transmitted into three different TPSs, including Advanced Workstation (GE), iPLAN (BrainLab), and Pinnacle (Phillips). As the result, we found that the larger phantom in three TPSs regardless of the slice thickness or pitch, the volume reconstruction errors were almost within 3%. On the other hand, the errors of volume reconstruction of the smallest phantom regardless of its thickness or pitch were large. It will be increased up to 12% when 5 mm slice thickness was used. The factors which affected the volume reconstruction errors were slice thickness and the volume of the object size. The impact of pitch and the different TPSs to the volume reconstruction were not obvious. We found that the larger slice thickness in small object, the larger reconstruction errors. There are volume differences between TPSs but not obvious. The major reason caused the volume reconstruction errors was the jagged effect on the edge of images which caused the judging errors on the HU value.
延伸閱讀
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