左乳癌保乳术后瘤床同步推量sIMRT与HT剂量学研究

The dosimetric study of two techniques,sIMRT and HT,for simultaneous integrated boost of tumor bed after breast-conserving surgery for left breast cancer

目的探讨左乳癌保乳术后瘤床同步推量静态调强放疗(sIMRT)与螺旋断层放疗(HT)两种放疗技术的剂量学特点。方法选取左乳癌保乳术后银夹标记瘤床的患者23例,采用医科达Monaco5.11计划系统设计sIMRT计划、安科锐TomoTherapy计划系统设计HT计划,处方剂量PGTV:5750cGy/25F、PTV:5000cGy/25F,比较两组计划靶区及危及器官剂量学参数。结果HT计划靶区适形度PGTV和PTV适形度指数CI略高于sIMRT计划,但差异无统计学意义(P>0.05),HT计划均匀性指数HI低于sIMRT计划,差异有统计学意义(P<0.05);危及器官剂量学参数左肺V_(5)、V_(20)、D_(mean),右肺V_(5)、D_(mean),心脏V_(30)、D_(mean),右乳腺D_(mean),脊髓D 2比较,除心脏V_(30) HT计划低于sIMRT计划(P<0.05),其余参数HT计划明显高于sIMRT计划(均P<0.05)。结论HT计划相较于sIMRT计划有着更好的靶区适形度和均匀度,但sIMRT计划相较于HT能够更好的保护危及器官。综合分析左乳癌保乳术后瘤床同步推量sIMRT计划获益要大于HT计划。

Objective To explore the dosimetric characteristics of two radiotherapy techniques,static Intensity-Modulated Radio Therapy(sIMRT)and Helical Tomotherapy(HT),of simultaneous integrated boost of tumor bed after breast conserving surgery for left breast cancer.Methods Twenty-three patients with tumor beds marked by silver clips after breast-conserving surgery for left breast cancer were selected.Elekta Monaco 5.11 planning system was used to design sIMRT plan and Ankerui TomoTherapy planning system was used to design HT plan,with prescription dose PGTV:5750cGy/25F,PTV:5000cGy/25F.The dosimetric parameters of planned target areas and organs at risk between the two groups were compared.Results Conformity and uniformity of the HT plan for the target area is better than those of the sIMRT plan.The homogeneity index between the two is statistically different(P<0.05),but the conformity index has no statistical difference(P=0.053,P=0.089).The organ-at-risk dosimetric parameters,left lung V5,V20,D_(mean),right lung V5,D_(mean),heart V30,D_(mean),right breast D_(mean),spinal cord D2,were compared,with the heart V30 of HT being lower than that of sIMRT(P<0.05)and the other parameters of HT being significantly higher than those of sIMRT(P<0.05).Conclusion Compared with sIMRT plan,HT plan had better conformity and uniformity of the target area,but sIMRT plan could protect the organs at risk better than HT plan.On the whole,sIMRT presented more benefits than HT plan in terms of simultaneous integrated boost of tumor bed after breast-conserving surgery for left breast cancer.