臺灣博碩士論文加值系統

研究背景:
放射治療在食道癌的治療上具有非常重要之地位。食道癌病人接受放射治療產生的併發症中，以急性放射性肺炎(radiation pneumonitis, RP)最為常見，主要與正常肺臟接受低輻射劑量有關。本研究針對螺旋斷層治療技術於食道腫瘤設計假體實驗，目的是探討扇形完全阻擋(fan-shaped complete block, FSCB)和肺臟劑量之關係，期望來預估肺臟體積接受5 Gy以上輻射劑量之比例(V5)，且進一步分析其他危及器官(organs at risk, OARs)劑量之變化，評估適合使用的FSCB角度。

材料與方法:
本研究使用擬人假體(anthropomorphic body phantom)，於兩側肺臟中設計FSCB，其FSCB體積會形成不被射束照射的肺臟體積(non-irradiated volume, VNR)，以VNR所佔肺臟體積之比例預測肺臟V5。本研究分為兩個部分，第一部分設計FSCB 10ﾟ至150ﾟ及不使用FSCB(non-block)之治療計劃，共16個放射治療計劃。在治療計劃統計分析上，使用皮爾森相關(Pearson correlation)分析FSCB角度及VNR所佔比例與肺臟劑量之相關性，並探討預測V5之準確性。第二部分評估FSCB 70ﾟ至150ﾟ治療計劃中肺臟、心臟、脊髓神經之劑量參數、計劃靶體積劑量分佈均勻度指標(homogenous index, HI)及順形度指標(conformal number, CN)，用來評估適合使用的FSCB角度。

結果:
第一部分結果發現在右肺中，FSCB角度與降低右肺平均劑量(r＝-0.988, P < 0.05)及V5(r＝-0.994, P < 0.05)呈高度相關，與降低右肺V20 (r = -0.616, P < 0.05)呈中度相關；VNR所佔比例與降低右肺平均劑量(r＝-0.997, P < 0.05)及V5(r＝-0.999, P < 0.05)也呈高度相關，與降低右肺V20 (r = -0.660, P < 0.05)呈中度相關。在左肺中，FSCB角度與降低左肺平均劑量(r = -0.989, P < 0.05)、V20 (r = -0.979, P < 0.05)及V5 (r = -0.991, P < 0.05)呈高度相關；VNR所佔比例與降低左肺平均劑量(r = -0.997, P < 0.05)、V20 (r = -0.982, P < 0.05)及V5 (r = -0.998, P < 0.05)也呈高度相關。在預測V5方面，V5預測值和實驗值差異很小，均在3.7%左肺或右肺體積以內。第二部分結果發現，隨FSCB角度越大，肺臟之V5、V10、V15、V20以及平均劑量下降，心臟之V30及平均劑量上升。應用FSCB 80ﾟ至140ﾟ之治療計劃，均能達到本研究訂定之危及器官劑量限值規定。

討論與結論:
螺旋斷層治療技術於食道癌放療計劃中，應用FSCB設計有助於降低肺臟劑量(平均劑量、V20、V5)，FSCB角度及VNR所佔比例與降低肺臟平均劑量、V5呈高度相關。此外，在評估適合使用的FSCB角度，應用FSCB 80ﾟ至140ﾟ之治療計劃使得危及器官均抑低至劑量限值以內，能降低食道腫瘤放射治療之併發症。

Introduction:
Radiation therapy is an important component in the multimodality treatment for esophageal cancer. Radiation pneumonitis (RP) is an acute complication for radiotherapy of esophageal cancer and is associated with the cumulative low dose in lung tissue. This study aims to evaluate the relationship between the fan-shaped complete block (FSCB) and lung dose, and to predict the proportion of the lung volume receiving 5 Gy (V5) utilizing various designs of the FSCB in helical tomotherapy. In addition, we analyze the dosimetric parameters for organs at risk (OARs) and evaluate the appropriate FSCB angles.

Material and Methods:
We simulated virtual esophageal tumor treated by Tomotherapy on an anthropomorphic body phantom. The FSCB was defined as the fan-shaped radiation restricted area located in both lungs and the volume of FSCB formed the non-irradiated volume (VNR). The proportion of the VNR in lung (VNR ratio) was used to predict the V5. Our study included two parts.In the first part, sixteen treatment plans were performed with non-block design and FSCB with different fan angles (from 10ﾟto 150ﾟ, with increment of 10ﾟ). The association between FSCB angle, VNR ratio and lung dose were evaluated using Pearson correlation analysis. The actual value and predictive value of V5 were compared. In the second part, the homogeneous index (HI) and conformal number (CN) of PTV and the dosimetric quality for lung, heart, and spinal cord were determined for each treatment scheme with FSCB 70ﾟto 150ﾟ to evaluate the FSCB angles suitable for use.

Result:
First, in the right lung, FSCB angle was highly correlated to reduced mean dose (r＝-0.988, P < 0.05) and V5 (r＝-0.994, P < 0.05), and moderately correlated to reduced V20 (r = -0.616, P < 0.05).VNR ratio was also highly correlated to reduced mean dose (r＝-0.997, P < 0.05) and V5 (r＝-0.999, P < 0.05), and moderately correlated to reduced V20 (r = -0.660, P < 0.05). In the left lung, FSCB angle was highly correlated to reduced mean dose (r = -0.989, P < 0.05), V20 (r = -0.979, P < 0.05) and V5 (r = -0.991, P < 0.05). VNR ratio was also highly correlated to reduced mean dose (r = -0.997, P < 0.05), V20 (r = -0.982, P < 0.05) and V5 (r = -0.998, P < 0.05).The difference between the actual value and predictive value of V5 was within 3.7%. Second, we found the V5, V10, V15, V20 and mean dose for the lungs were lower when the FSCB angle increased, with simultaneous increase of the maximum dose of spinal cord, mean dose, and V30 of the heart. Treatment plans with FSCB 80ﾟto 140ﾟdesigns could reach the dose constraints of OARs.

Discussion and conclusion:
Helical tomotherapy using FSCB plans provided reduction of the mean dose, V5 and V20 to lungs for esophageal cancer. The FSCB angle and VNR ratio were highly associated with reduction of mean dose and V5. In addition, treatment plans with FSCB 80ﾟto 140ﾟ in helical tomotherapy were a feasible protective method for reducing complications from radiotherapy of esophageal cancer.

目錄
誌謝 I
中文摘要 II
Abstract IV
目錄 VI
圖目錄 IX
表目錄 XI
第一章 緒論 1
1.1 前言 1
1.2 研究背景 1
1.3 研究目的 2
第二章 食道癌與放射治療 4
2.1 食道解剖構造及生理 4
2.2 食道癌流行病學及病因 4
2.3 食道癌的病程分期與治療方式 5
2.4 食道癌的放射治療 6
2.5 文獻回顧 7
2.5.1 胸腔腫瘤放射治療相關併發症之研究 7
2.5.2 新式放療技術治療食道癌之研究 11
第三章 材料與方法 13
3.1 擬人假體 13
3.2 螺旋斷層放射治療儀系統 14
3.3 電腦斷層模擬定位掃描 18
3.4 電腦治療計劃規劃 18
3.4.1 食道腫瘤及周圍正常組織器官之描繪 18
3.4.2 FSCB之描繪方法 19
3.4.3 FSCB體積與不被射束照射到的肺臟體積VNR 21
3.5 實驗設計與步驟 29
3.5.1 第一部分−探討V5快速預測法 29
3.5.2 第二部分−探討適合使用的FSCB角度 30
3.6 評估治療計劃的方式 32
3.6.1 等劑量曲線分佈圖(isodose curve) 32
3.6.2 劑量體積直方圖(dose volume histogram, DVH) 32
3.6.3 靶體積劑量分佈指標 33
3.7 統計分析 34
第四章 結果 36
4.1 第一部分−探討V5快速預測法 36
4.1.1 FSCB角度與FSCB體積 36
4.1.2 肺臟劑量之比較 37
4.1.3 FSCB與肺臟劑量之相關性 39
4.1.4 V5預測值與實驗值 42
4.2 第二部分−探討適合使用的FSCB角度 43
4.2.1 等劑量曲線分佈圖 43
4.2.2 腫瘤與危及器官劑量之比較 44
第五章 討論 47
5.1 第一部分−探討V5快速預測法 47
5.1.1 FSCB角度與FSCB體積之關係 47
5.1.2 FSCB治療計劃與non-block治療計劃之比較 48
5.1.3 FSCB與肺臟劑量之相關性探討 49
5.1.4 V5預測結果之探討 50
5.2 第二部分−探討適合使用的FSCB角度 51
5.2.1 等劑量曲線分佈圖之比較 51
5.2.2 適合FSCB角度之探討 51
5.3 第一部分及第二部分治療計劃之比較 54
5.4 食道癌放射治療危及器官劑量之比較 57
5.5 研究限制 59
第六章 結論 62
參考文獻 63

圖目錄
圖 1-1、FSCB 區域阻擋治療射束入射與出射肺臟體積 3
圖 2-1、食道構造示意圖 4
圖 2-2、食道腫瘤治療體積 7
圖 2-3、V5 與急性放射性肺炎發生率之關係 9
圖 2-4、平均心臟劑量與慢性心臟冠狀動脈疾病機率之關係 10
圖 3-1、成年男性擬人假體 13
圖 3-2、螺旋斷層放射治療儀外觀 14
圖 3-3、螺旋斷層放射治療儀的重要元件 15
圖 3-4、機器中心點與虛擬中心點 16
圖 3-5、虛擬食道腫瘤之橫切面、矢狀切面及冠狀切面 19
圖 3-6、FSCB θ ﾟ= 80 ﾟ設計步驟示意圖 21
圖 3-7、FSCB 體積之橫切面與冠狀切面示意圖 23
圖 3-8、胸廓橫徑 T 與計劃靶體積(PTV)橫徑 E 測量示意圖 25
圖 3-9、模擬的 FSCB 扇形柱狀體積 25
圖 3-10、照野外的肺臟體積示意圖 28
圖 3-11、治療計劃中右肺不被射束照射到的肺臟體積 VNR 所佔比例 30
圖 3-12、劑量體積直方圖 33
圖 4-1、右肺中 FSCB 角度及 VNR 所佔比例與肺臟劑量之相關性 40
圖 4-2、左肺中 FSCB 角度及 VNR 所佔比例與肺臟劑量之相關性 41
圖 4-3、兩側肺臟的 V5 預測值和 V5 實驗值 42
圖 4-4、FSCB 治療計劃之等劑量曲線分佈圖 44
圖 5-1、第一部分與第二部分 FSCB 治療計劃之肺臟 V5 55
圖 5-2、第一部分與第二部分 FSCB 治療計劃之肺臟 V20 56
圖 5-3、第一部分與第二部分 FSCB 治療計劃之平均肺臟劑量 56
圖 5-4、器官不對稱可使用非對稱之 FSCB 角度 59
圖 5-5、腫瘤位置跨區 60
圖 5-6、腫瘤長度 Lt 61

表目錄
表 2-1、正常組織器官的劑量限值以及相對應發生併發症的機率 11
表 3-1、危及器官劑量限值 31
表 4-1、兩側肺臟中 FSCB 角度、FSCB 體積及 VNR 所佔比例 37
表 4-2、FSCB 角度、VNR 所佔比例與相對應的肺臟劑量關係 38
表 4-3、危及器官劑量與計劃靶體積(PTV)之劑量分佈指標 46
表 5-1、本研究危及器官劑量與其他文獻之比較 58

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