摘要目的：探讨左侧乳腺癌术后3种不同放疗计划的剂量学差异。方法收集江苏省苏北人民医院2011年3月至2013年3月期间收治的15例左侧乳腺癌术后患者，分别设计3D?CRT、dIMRT和RapidArc计划，处方剂量均为5000 cGy。利用剂量体积直方图分析临床靶区（CTV）、危及器官（OAR）的评价指标，包括CTV的平均剂量Dmean、最大剂量Dmax（D2%）和最小剂量Dmin（D98%），靶区剂量均匀性指数HI，靶区适合度指数CI，以及两侧肺接受5、20、30 Gy的体积百分比V5、V10、V20、V30和平均剂量Dmean，对侧乳腺的平均剂量Dmean、D1%，心脏的Dmean、V10，脊髓1%体积接受照射的最大剂量D1%。结果3D?CRT计划CTV各评价指标中除HI、D2%外，均劣于dIMRT和RapidArc计划（均P<0.05）。dIMRT和RapidArc计划相比，仅在Dmean、V95%的差异有统计学意义（均P<0.05），且以RapidArc计划Dmean更接近处方剂量，V95%覆盖率较高达97.44%。对于患侧肺，3种计划中3D?CRT的V5、V10最低（均P<0.05），而V20、V30最高（均P<0.05），而RapidArc和dIMRT患侧肺V5、V10稍高（均P<0.05）。对侧肺和心脏3D?CRT各评价指标最低（均P<0.05）。对侧乳腺D1%则以dIMRT和RapidArc计划较低，分别为（1770.89±121.16）cGy和（1839.92±92.77）cGy。而脊髓D1% dIMRT和RapidArc计划较高，分别为（1990.12±61.52）cGy和（1927.38±43.67）cGy。正常组织接受剂量为5~15 Gy体积时3D?CRT计划明显最低，而RapidArc计划相对较高。RapidArc计划的MU数和治疗时间最少，仅为dIMRT计划的49.33%和55.86%。结论3种计划均能够满足乳腺癌术后放疗的临床剂量学要求。dIMRT和RapidArc计划靶区适形度更优，且RapidArc计划具有较少总MU数和较短的总治疗时间的优势。

abstractsObjective To investigate the difference in dosimetry among three different plans for postoperative radiotherapy of the left breast cancer. Methods Between March 2011 and March 2013,a total of 15 postoperative patients with left breast cancer in Subei People ’s Hospital of Jiangsu Province received radiotherapy based on 3D?CRT,dIMRT or RapidArc planning,with a prescribed dose of 5 000 cGy. Dose volume histogram analysis was used to show the evaluation measures of clinical target volume (CTV)and organ at risk(OAR)which include the mean(Dmean),maximum(D2%)and minimum(D98%) doses of CTV,homogeneity index(HI)and conformity index(CI)of the CTV,percentage volumes with 5 (V5),10(V10),20(V20)and 30(V30)Gy and mean dose(Dmean)of the lung,Dmean and D1% of the contralateral breast,Dmean and V10 of the heart,D1% of the spinal cord with 1% of its volume subjected to radiation. Results Except for the HI and D2%,evaluation measures of 3D?CRT plan were inferior to those&nbsp;of dIMRT and RapidArc plans (all P<0.05). Between dIMRT and RapidArc plan,only Dmean and V95%differed(all P<0.05);with RapidArc plan,the Dmean was closer to the prescription dose,and the V95%coverage rate was as high as 97. 44%. At the ipsilateral lung,3D?CRT yielded the lowest V5 and V10(all P<0.05)and highest V20 and V30(all P<0.05),while the RapidArc and dIMRT yielded moderate values of V5 and V10(all P<0. 05). The 3D?CRT yielded the lowest of each evaluation measure at the contralateral lung and heart(all P<0.05). The contralateral breast D1%was lower with dIMRT[(1 770.89±121.16)cGy]and RapidArc[(1 839.92±92.77)cGy]plans. The dIMRT and RapidArc plans yielded higher D1%of the spinal cord[(1 990.12 ± 61.52)cGy and(1 927.38 ± 43.67)cGy,respectively]. The 3D?CRT plan yielded the lowest percentage volumes of normal tissue with the radiation doses ranging from 5 to 15 Gy. RapidArc plan took less MU and treatment time,which account for only 49.33% and 55.86%,respectively,of those in dIMRT plan. Conclusion All of the three plans are able to meet the requirement of clinical dosimetry in the postoperative radiotherapy for left breast cancer. The dIMRT and RapidArc plans may be more conformable for the target volume;in addition,and RapidArc plan is more advantageous in terms of less total MU and treatment time.