基于Monaco的不同布野方式在左乳腺癌保乳术后调强放疗中的剂量学差异

Dosimetric differences of different radiation modes based on Monaco in postoperative intensity modulated radiotherapy of patients with left breast-conserving surgery for breast cancer

  • 摘要:
      目的  探讨Monaco计划系统中不同布野方式对左乳腺癌保乳术后调强放疗剂量学的影响。
      方法  选取左乳腺癌保乳术后患者12例,采用Monaco计划系统,在相同的优化条件下每例患者分别设计单野双弧(1F2A)、两野双弧(2F2A)、动态调强(dMLC)3种计划,比较3种计划的靶区及危及器官剂量学参数。
      结果  3种计划的靶区剂量均能满足临床要求, 2%计划靶区受到的照射剂量(D2)、98%计划靶区受到的照射剂量(D98)、50%计划靶区受到的照射剂量(D50)、适形度指数(CI)、均匀性指数(HI)等参数比较, 1F2A计划均优于2F2A、dMLC计划,差异均有统计学意义(P < 0.05)。2F2A计划得到的左肺接受5 Gy剂量照射的体积(V5)以及10、20、30 Gy剂量照射的体积(V10V20V30)和平均剂量(Dmean)均低于1F2A计划和dMLC计划,其中V5V10Dmean的差异均有统计学意义(P < 0.05)。与1F2A计划相比, 2F2A计划和dMLC计划的右肺V5V10Dmean以及右乳的Dmean、脊髓的Dmax均降低,差异均有统计学意义(P < 0.05)。在心脏V5Dmean方面, dMLC计划均低于1F2A计划和2F2A计划,差异均有统计学意义(P < 0.05)。2F2A计划的子野数与1F2A计划、dMLC计划相比均降低,差异均有统计学意义(P < 0.05)。
      结论  3种计划均能满足临床要求, 2F2A计划能降低患侧肺、心脏等危及器官的受照剂量和体积。综合考虑计划质量和执行效率,建议左乳腺癌保乳术后放疗采用2F2A布野方式的容积旋转调强技术。

     

    Abstract:
      Objective  To investigate the effects of different radiation modes in Monaco planning system on the dosimetry of postoperative intensity modulated radiotherapy of patients with left breast-conserving surgery for breast cancer.
      Methods  Twelve patients with left breast-conserving surgery for breast cancer were selected. The Monaco planning system was used to design single-field and double-arc (1F2A), two-field and double-arc (2F2A), and dynamic multi-leaf collimator (dMLC) plans for each patient under the same optimal conditions. The target areas and organ-at-risk dosimetric parameters of the three plans were compared.
      Results  The target doses of the three plans all met the clinical requirements. In the comparison of the parameters such as radiation dose to 2% of the planned target area (D2), radiation dose to 98% of the planned target area (D98), radiation dose to 50% of the planned target area (D50), conformity index (CI) and homogeneity index (HI), 1F2A plan was significantly better than 2F2A plan and dMLC plan (P < 0.05). The volumes of left lung exposed to 5 Gy dose (V5), exposed to 10 Gy dose V10, exposed to 20 Gy dose V20, exposed to 30 Gy dose V30 and mean dose (Dmean) of 2F2A plan were lower than those of 1F2A plan and dMLC plan, and significant between-groups differences were observed in V5, V10 and Dmean (P < 0.05). Compared with 1F2A plan, V5, V10 and Dmean of right lung, Dmean of right breast and maximum dose (Dmax) of spinal cord in 2F2A plan and dMLC plan were significantly decreased (P < 0.05). Results ofV5 and Dmeanof heart, in dMLC plan were significantly lower than those of 1F2A plan and 2F2A plan (P < 0.05). The number of segments in 2F2A plan was significantly lower than that in 1F2A plan and dMLC plan (P < 0.05).
      Conclusion  All of the three plans can meet the clinical requirements, but the 2F2A plan can reduce the irradiated dose and volume of organs-at-risk. Considering the quality of the plan and the performance efficiency, it is suggested that the volume rotation intensity modulated technique with 2F2A field distribution should be used in postoperative radiotherapy of patients with left breast-conserving surgery for breast cancer.

     

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