本論文研究以食道癌為目標，利用傳統L型直線加速器Edge和新型環形直線加速器Halcyon進行於治療食道癌的放射治療計畫回溯性劑量學比較與預測危及器官損傷。食道癌腫瘤分類為下段、中下段、中段、整段。本研究分別比較局部性和整體性治療計畫參數為體積劑量直方圖(Dose volume Histogram, DVH)、劑量梯度指標(Gradient Index GI)、順型指數(Conformity Index, CI)以及均勻性指數(Homogeneity, HI)。危及器官損傷程度以風險因子符合指數(Risk Factor Conformity Index, RFC)為基礎。局部性劑量參數比較以計畫靶體積(Planning Target Volume, PTV)及危及器官(Organ At Risk, OAR)進行差異比較，相關性差異以統計分析進行顯著性評估。
研究結果顯示Halcyon和Edge，共20個治療計畫能夠達成臨床目標。局部性評估包括下段、中下段、中段、整段部分，其計畫靶體積相關參數呈現相近的趨勢。心臟平均劑量、V_20Gy%、V_30Gy%與脊髓最大劑量皆是Halcyon呈現較低的趨勢，針對肺臟低劑量區V_5Gy%、V_10Gy%則是Edge呈現較低的趨勢。整體性評估共納入20個治療計畫。針對計畫靶體積相關參數如CI, HI, GI呈現相近數值且無顯著性差異，表示針對腫瘤Halcyon能夠達成與Edge一樣的目標。危急器官方面發現脊髓最大劑量和心臟V_20Gy所佔的體積百分比Halcyon治療計畫分別降低其平均劑量和接收20戈雷體積百分比能夠有更好的組織防護並且具顯著性差異，但肺臟部分左肺臟V_10Gy和V_5Gy所接收到的體積百分比是Edge較少且具有顯著性差異。治療計畫目標希望降低脊髓、心臟等會出現高劑量危急器官所接收的劑量建議採用Halcyon，如希望降低左右肺臟接收低劑量所佔體積建議採用Edge。研究數據證明針對食道癌放射治療Halcyon能夠達到與舊型儀器Edge一樣的臨床目標，卻能夠減少治療時間，且針對脊髓、心臟能夠有更好的組織防護且能降低其接受劑量。
使用風險評估因子計算，能讓使用者在病患實際治療前更清楚對每個治療計畫中各個危及器官進行損傷預測評估。

This study focuses on esophageal cancer, performing a retrospective dosimetric comparison and prediction of organ-at-risk (OAR) damage using the traditional L-shaped linear accelerator, Edge, and the new ring-shaped linear accelerator, Halcyon, in the treatment plans for esophageal cancer. Esophageal tumors were classified into lower, middle-lower, middle, and entire segments. The study compares both local and overall treatment plan parameters, including Dose Volume Histogram (DVH), Gradient Index (GI), Conformity Index (CI), and Homogeneity Index (HI). The extent of OAR damage is assessed based on the Risk Factor Conformity Index (RFC). Local dosimetric parameter comparisons focus on Planning Target Volume (PTV) and OAR, with significant differences evaluated through statistical analysis.
The results indicate that both Halcyon and Edge, across 20 treatment plans, can achieve clinical objectives. Local evaluations include lower, middle-lower, middle, and entire segments. For the heart, Halcyon shows a lower trend in mean dose, V_20Gy%, and V_30Gy%, as well as for the maximum dose to the spinal cord. In contrast, for low-dose areas in the lungs, Edge shows a lower trend inV_5Gy%,V_10Gy%. In the overall esophageal cancer treatment plans, there are no significant differences in PTV-related parameters such as CI, HI, and GI, indicating that Halcyon can achieve the same objectives as Edge for tumor targeting. For OARs, the maximum dose to the spinal cord and the heart V_20Gy% were significantly reduced with the Halcyon treatment plan, indicating better tissue sparing. However, for the lungs, the left lung V_10Gy% ,V_5Gy%) was significantly less with Edge. For treatment plan objectives, it is recommended to use Halcyon if the goal is to reduce the dose received by high-dose OARs such as the spinal cord and heart. On the other hand, Edge is recommended if the goal is to reduce the volume of the lungs (both left and right) receiving low doses. Research data demonstrate that for esophageal cancer radiotherapy, Halcyon can achieve the same clinical objectives as the older Edge device while reducing treatment time and providing better tissue protection for the spinal cord and heart.
Using the risk assessment factor calculation allows users to better predict and evaluate damage to each OAR in each treatment plan before actual patient treatment.

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