目的：本研究為螺旋刀、強度調控放射治療與相切照野中照野用於雙側乳房癌症治療之劑量差 異分析。 材料與方法：本研究是採用回溯性方式擷取本科已治療過的 10 名乳癌患者，接受乳房保留手 術後，至本科接受後續放射治療，病理期是 pT1 ∼T2。每位病人都接受電腦斷層攝影治療規 劃，分別以三種治療技術：螺旋刀治療（Tomotherapy）、強度調控放射治療（IMRT）和相切 照野中照野（tangential field-in-field, FIF）分析，並比較各技術對治療體積的劑量、均勻度指標 （Homogeneity index, HI）、順行度指標（Conformity index, CI）和重要器官的劑量。 結果：相較於 IMRT 和 FIF，Tomotherapy 於心臟平均劑量呈現最低（tomotherapy = 3.67 Gy， IMRT = 4.51 Gy and FIF = 4.84 Gy；p < 0.05）。同時，比起 IMRT 和 FIF，Tomotherapy 在降低 左側與右側肺部的平均劑量更優（右側肺平均劑量為 6.44，9.08 and 10.03 Gy for Tomotherapy， IMRT 和 FIF；p < 0.05；左側肺部平均劑量：6.33 , 7.85 and 8.64 Gy for Tomotherapy，IMRT 和 FIF；p = 0.002）。而在冠狀動脈和左前下行動脈的平均劑量為 Tomotherapy = 12.07和 19.41 Gy，IMRT = 16.99 和 27.86 Gy，FIF = 19.24 和 30.94 Gy。以及左側和右側乳房的順行度指 標（Conformity index, CI）為 Tomotherapy =1.08 ± 0.01 和 1.07 ± 0.02，IMRT = 1.07 ± 0.02 和 1.08 ± 0.01，FIF = 1.12 ± 0.03 and 1.11 ± 0.01 與均勻度指標（Homogeneity index, HI）為 Tomotherapy = 1.36 ± 0.08 和 1.53 ± 0.46，IMRT = 1.65 ± 0.44 和 1.51 ± 0.26，FIF = 1.82 ± 0.51 和 1.78 ± 0.32。 結論：螺旋刀治療，在心臟與肺部和冠狀動脈呈現的劑量是較低的，表示此治療技術在雙側乳 房癌症治療是有幫助的。

Purpose : This study compared the treatment efficacy of tomotherapy, intensity-modulated radiotherapy (IMRT) and tangential field in field (FIF) for bilateral breast cancer. Materials and Methods : We enrolled 10 patients with breast cancer in this study. All patients had early stage breast cancer (pTis, T1, or T2). A total dose of 5040 cGy was administered for adjuvant breast irradiation with IMRT and tomotherapy for each patient in the treatment planning system. In this study, we compared the treatment efficacy of tangential field-in-field (FIF), IMRT and tomotherapy for bilateral breast cancer. We analyzed the bilateral whole-breast dose coverage, conformity and homogeneity indices, and dose–volume constraints of normal tissues (the right and left lungs and heart). Results : Tomotherapy was more efficient than IMRT and FIF, exhibiting significant improvements in reducing the volume of normal tissues (heart mean doses: tomotherapy = 3.67 Gy, IMRT = 4.51 Gy and FIF = 4.84 Gy; p < 0.05). Moreover, tomotherapy required a lower mean lung dose (right lung mean dose = 6.44, 9.08 and 10.03 Gy for tomotherapy, IMRT and FIF, respectively; p < 0.05; left lung mean dose = 6.33, 7.85 and 8.64 Gy for tomotherapy, IMRT and FIF, respectively; p = 0.0002). We also showed the mean doses of coronary artery and left anterior descending artery (LAD): tomotherapy = 12.07 and 19.41 Gy, IMRT = 16.99 and 27.86 Gy, FIF = 19.24 and 30.94 Gy, respectively. The conformity indices (V95%/VPTV) of the right and left breasts were 1.08 ± 0.01 and 1.07 ± 0.02 for tomotherapy, respectively, and 1.07 ± 0.02 and 1.08 ± 0.01 for IMRT, and 1.12 ± 0.03 and 1.11 ± 0.01, respectively, in FIF respectively. Moreover, the homogeneity indices of the right and left breasts were 1.36 ± 0.08 and 1.53 ± 0.46 for tomotherapy, respectively, and 1.65 ± 0.44 and 1.51 ± 0.26 for IMRT, respectively and 1.82 ± 0.51 and 1.78 ± 0.32, respectively, in FIF. Conclusion : Tomotherapy significantly reduced the dose volume of the heart and mean dose for the lungs and coronary vessels. However, long-term follow-up is warranted to ensure low normal tissue toxicity in these patients.