两种左侧乳腺癌保乳术后 FIF和 DMPO-IMRT结合照射技术的剂量学比较

摘要

Objective To evaluate the dose distribution of target volume and normal tissues of 2 techniques combined FIF with DMPO-IMRT for left breast cancer after conserving surgery.Methods 30 patients with left breast cancer treated with conserving surgery were randomly selected,the CT images of patients were transmitted to the pinnacle3 treatment planning system to contour the tumor target.Treatments planning of combined FIF with 2 different DMPO-IMRT fields were worked out by comput-er working station,respectively.Meeting 95%PTV received the prescribed dose,the dose distributions of plan target volume and normal tissues,conformal index( CI) and heterogeneous index( HI) were evaluated in terms of the dose volume histogram( DVH) . Results There were no significant difference of HI,CI,PTV dose betweenⅠandⅡ.The dose received of heart was much dif-ferent betweenⅠandⅡat the V5 .There were no significant difference of average dose and V40 ,V50 in left lung betweenⅠandⅡ. However,the volume at V5、V10、V15、V20、V25、V30 in planⅠwere much smaller than that in planⅡ.The V5 of right lung in planⅠwere significantly lower than that in planⅡ.The mean dose and V5 of right breast received in planⅡwere similar with that in planⅠ.Conclusion The PTV received dose has no significant difference between the 2 kinds methods.In protection of the heart,right lung and right breast or other important crisis organs,plan Ⅰ is obviously much better than plan Ⅱ.Compared with planⅠ,planⅡis the optimal plan for clinical practice.%目的：评估早期乳腺癌保乳术后两种常用野中野加调强照射技术的靶区及其周围正常组织受照剂量的差异，为术后放疗方法的临床选择提供科学理论依据。方法随机选取左侧30例乳腺癌保乳术后患者，经CT扫描后将图像传至pinnacle3治疗计划系统中并由同一医生进行靶区勾画。每例患者均采用FIF技术和两种不同角度的DM-PO-IMRT技术两者相结合的照射方式对靶区进行两种不同角度（计划Ⅰ与计划Ⅱ）的计划设计。在满足PTV达到95％处方剂量的前提下，利用剂量体积直方图（ DVH）评价2种调强照射方法的靶区和周围正常组织照射剂量和靶区适形指数（ CI）及剂量不均匀性指数（ HI）。结果①靶区的最大、最小、平均剂量两者相似，且靶区剂量不均匀指数、适形指数两者差异无统计学意义。②对心脏保护，两种方式心脏接受的照射剂量除V5处计划Ⅰ优于Ⅱ外，其余均无明显差异。③对患肺的保护，两种计划的左肺受照平均剂量Dmean、以及高剂量照射区域V40、V50等处两者间差异无统计学意义；但在左肺接受的低剂量照射体积V5、V10、V15及中剂量照射体积V20、V25、V30计划Ⅰ明显小于计划Ⅱ，差异具有统计学意义（P＜0．05）。④对右肺的保护，在V5处右肺接受照射体积明显小于计划Ⅱ（P＜0．05）。⑤对右侧乳腺的保护，两者右侧乳腺受照剂量体积剂量无明显差异。结论两种调强设野方法的靶区照射剂量差异不大，但是在对心脏、患肺及健肺等重要危机器官的保护上方法Ⅰ明显优于Ⅱ。因此计划Ⅰ中使用的野中野与IMRT相结合的射野方式对于降低正常组织器官的辐射量具有重要意义，值得在临床推广应用。