目的：本研究之目的，主要是探討共平面體積調控弧形治療，與非共平面體積調控弧形治療，在 治療肝門靜脈血栓肝癌病患的治療計畫劑量分佈之差異。 材料與方法：本研究選取7 位肝門靜脈血栓肝癌病患，進行共平面體積調控弧形治療計畫，與非 共平面體積調控弧形治療計畫製作，治療次數25 次，醫囑劑量為50 Gy。所有治療計畫之劑量評 估參數，例如：均勻度指標及順形度指標，均歸一化到100% 的醫囑劑量可以包覆95% 的治療計 畫靶體積。危及器官如脊髓、腎臟、小腸及正常肝臟組織之劑量，則藉由魏克生符號等級檢定進 行統計分析。 結果：共平面與非共平面體積調控弧形治療計畫之平均順形度指標分別為0.809±0.059 和 0.847±0.043，而平均均勻度指標分別為 1.041±0.007 和1.047±0.008，統計結果顯示兩種治療 計畫在順形度指標及均勻度指標，並無顯著之差異。非共平面體積調控弧形治療計畫中脊髓最大 劑量值、左側腎臟之平均劑量以及正常肝臟組織之V5 、V10 、V20 、V30 、V40 、V50 均略低於共平面 體積調控弧形治療計畫，但是統計上並無顯著之差異。正常肝臟組織之平均劑量，由共平面體積 調控弧形治療計畫之17.15±5.00 Gy 顯著降低至非共平面體積調控弧形治療計畫之16.01±4.93 Gy（p= 0.018）。右側腎臟之平均劑量，由共平面體積調控弧形治療計畫之4.89±3.07 Gy 顯著 降低至非共平面體積調控弧形治療計畫之3.55±2.30 Gy（p= 0.018），而右側腎臟V18 之體積 亦由共平面體積調控弧形治療計畫之3.57±5.88% 顯著降低至非共平面體積調控弧形治療計畫之 0.93±2.44%（p= 0.043）。 結論：非共平面體積調控弧形治療技術，應用於肝門靜脈血栓之肝癌病患之治療計畫製作時，在 相同之治療計畫靶體積之劑量包覆度、劑量均勻度以及劑量順形度下，其可以降低正常肝臟組織 之平均劑量，以及右側腎臟之平均劑量及V18 之體積。

Purpose : To evaluate the dosimetric differences between coplanar and noncoplanar volume modulated arc therapy (VMAT) treatment plans for patients with hepatocellular carcinoma with portal vein tumor thrombosis. Materials and Method : Both coplanar and noncoplanar VMAT plans of seven patients with HCC and PVT were designed with a prescribed dose 50 Gy in 25 fractions. The plan quality indexes, such as dose conformity and dose homogeneity, would be calculate in the same dose coverage of 100% prescribed dose covered 95% PTV. The doses of spinal cord, kidney, small bowel and normal liver (whole liver minus CTV) would be collect and analyzed by Wilcoxon signed-rank test. Results : The average conformity of coplanar and noncoplanar VMAT plans were 0.809 ± 0.059 and 0.847 ± 0.043, and the average homogeneity were 1.041 ± 0.007 and 1.047 ± 0.008. There were no significant difference in both conformity and homogeneity between two plan sets. The maximal dose in spinal cord and small bowel, and mean dose in left side kidney, and V5, V10, V20, V30, V40, V50 of normal liver in noncoplanar VMAT plans were slightly lower than that in coplanar plans, but without significant difference. The mean dose of normal liver were significantly decreased from 17.15 ± 5.00 Gy in coplanar VMAT plans to 16.01 ± 4.93 Gy in noncoplanar VMAT plans. (p= 0.018) The mean dose of right side kidney were significantly decreased from 4.89 ± 3.07 Gy in coplanar VMAT plans to 3.55 ± 2.30 Gy in noncoplanar VMAT plans (p= 0.018), and V18 of right side kidney were significantly decreased from 3.57 ± 5.88% in coplanar VMAT plans to 0.93 ± 2.44% in noncoplanar VMAT plans (p= 0.043). Conclusions : The noncoplanar VMAT plans used in treatments of HCC patients with PVT may decrease mean dose of normal liver and mean dose and V18 of right side kidney in similar PTV dose coverage, homogeneity and conformity.