中文摘要：

目的比较三维适形（3D-CRT）、逆向调强（IMRT）及旋转调强（V—MAT）3种部分乳腺外照射（EB．PBI）治疗计划的剂量学差异。方法选择定位影像资料完整的12例保乳术后行EB—PBI患者，每例患者分别设计3D—CRT、IMRT、V—MAT3种治疗计划，比较3种计划的靶区剂量分布、危及器官受照剂量及所需机器跳数（MU）和治疗时间。结果3D-CRT计划的靶区适形度最差，V—MAT计划的处方剂量靶区覆盖率及靶区剂量均匀性最差。3D-CRT计划中患侧肺K、V10和平均剂量低，而患侧肺‰高；计划间患侧肺K。差异无统计学意义；V-MAT计划中15、20和25Gy剂量包绕的同侧正常乳腺体积少；对于心脏以、平均剂量及最大剂量、对侧肺平均剂量、甲状腺平均和最大剂量．IMRT〉V-MAT〉3DCRT，计划间两两比较差异均有统计学意义（z=-2．94～-2．09，P〈0．05）。3D．CRT、IMRT和V—MAT计划所需MU值分别为417．6±34．4、772．8±54．4和631．0±109．0，计划间两两比较差异均有统计学意义（z=-2．93、-2．76、-2．93，P〈0．05）；V—MAT计划施照时间短。结论对于部分乳腺癌的放射治疗，旋转调强计划在降低患侧靶区外正常乳腺组织受照射剂量和减少治疗时间方面优势比较明显。

英文摘要：

Objective To compare the dosimetric differences of three-dimensional conformal radiotherapy （3D-CRT）, intensity-modulated radiotherapy （IMRT） and volumetric modulated arc radiotherapy（V-MAT） for external beam partial breast irradiation. Methods Twelve patients with breast cancer receiving breast-conserving surgery and external beam partial breast irradiation were enrolled. Three different techniques including 3D-CRT, IMRT and V-MAT were designed for each patient. The dosimetry in the target, the dose to the organs at risk（OAR） , the MU and delivery time were compared. Results All three plans met the clinical requirement. 3D-CRT showed the worst conformity in target. V-MAT provided the lowest target coverage and homogeneity in target. 3D-CRT plans showed the lowest values for the Vs, Vio, mean dose and the highest values for 1/3o in the ipsilateral lung. No statistically significant differences were observed in I/2o of the ipsilateral lung among three plans. V-MAT showed the lowest values in ipsilateral normal breast volume 15, 20 and 25 Gy post-irradiation. For V5 , the mean and max dose in heart, the mean dose in contralateral lung and the mean, max dose in thyroid, IMRT and 3D-CRT showed the highest and lowest value respectively（z = - 2.94 - - 2.09 ,P 〈 0.05 ）. The MUs in 3D-CRT, IMRT and V-MAT were 417.6 ±34.4, 772.8 ±54.4 and 631.0±109.0, respectively（z= -2.93, -2.76, -2.93,P 〈 0. 05 ）. V-MAT significantly reduced the delivery time. Conclusions V-MAT shows significant advantages in reducing the dose in the ipsilateral normal breast and the delivery time compared with 3D-CRT and IMRT.