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目的分析左侧乳腺癌保乳术后调强放疗(IMRT)靶区以及心脏、同侧肺的照射剂量分布情况。方法对保乳术后接受调强放疗的37例左侧乳腺癌患者采取CT定位并行调强放射治疗,采用IMRT及3D-CRT 2种照射计划,总剂量均为50 Gy,1次/d,5 d/周,共照射25次。观察比较两种计划的剂量学差异。结果 IMRT计划D95剂量高于3D-CRT计划,而IMRT的V105%、V110%、HI明显低于3D-CRT,具有统计学差异(P<0.05)。IMRT的肺V20、V30、V40以及心脏V5、V30、V40均显著低于3D-CRT的,具有统计学差异(P<0.05)。15例患者左侧乳腺体积超过500 cm3,22例小于500 cm3,经比较发现,两组患者IMRT计划的D95、V105、V110、HI比较无显著差异。结论 IMRT靶区剂量更接近于处方剂量,靶区剂量分布较3D-CRT更均匀,有更好的适形性,能更好地保护肺脏、心脏等周围组织,而且IMRT放射治疗受CTV影响较小,靶区内剂量均匀性较好。
Objective To analyze the dose distribution of IMRT and heart and ipsilateral lung after left breast conserving surgery. Methods Thirty-seven patients with left-sided breast cancer who underwent intensity modulated radiotherapy after breast-conserving surgery underwent CT-guided concurrent intensity modulated radiotherapy. The total dose of IMRT and 3D-CRT was 50 Gy, once per day, 5 d / week, a total of 25 shots. Differences in dosimetry between the two plans were observed. Results The dose of D95 in IMRT plan was higher than that in 3D-CRT plan. The IMRT of V105%, V110% and HI were significantly lower than that of 3D-CRT (P <0.05). The lung V20, V30, V40 and V5, V30 and V40 in lung of IMRT were significantly lower than that of 3D-CRT (P <0.05). Fifteen patients had a left breast volume of more than 500 cm 3 and 22 less than 500 cm 3. There was no significant difference in DMR, V105, V110, and HI between the two groups in the IMRT plan. Conclusion The dose of IMRT target is closer to the prescription dose, the target dose distribution is more uniform than 3D-CRT, and better conformality can protect the surrounding tissues such as lung and heart better, and IMRT radiation therapy is more affected by CTV Small, target dose uniformity better.