呼吸门控加调强放疗在早期乳腺癌保乳术后放疗中的应用

doi:10.3971/j.issn.1000-8578.2011.07.024

呼吸门控加调强放疗在早期乳腺癌保乳术后放疗中的应用

Intensity-modulated Radiotherapy with Active Breathing Coordinator Technique for Early Stage Breast Cancer after Breast-conserving Surgery

摘要

摘要: 目的通过与自由呼吸状态（FB）下常规切线野放疗比较，探讨呼吸门控技术（ABC）加调强放疗（IMRT）在早期乳腺癌保乳术后放疗中的应用价值。方法选择8例接受保乳手术的T1~2N0M0乳腺癌病例，其中左侧4例，右侧4例，分别在ABC及FB状态下行CT扫描，并在ABC状态下设计IMRT(ABC-IMRT)与FB状态下常规切线野放疗(FB-WBI)放疗计划。采用DVH及等剂量曲线来比较2种计划中PTV、OARs的剂量学差异。结果在两种计划中，95%PTV均接受47.5 Gy/25次；ABC-IMRT组与FB-WBI组的V90%、V105%、V110%分别为98.29% vs.97.71% (P＝0.041)、54.54% vs.72.22% (P＝0.035)、11.71% vs.30.69% (P＝0.014)；两组同侧肺的V20、V30分别为17.89% vs.22.20% (P＝0.000)、14.39% vs.18.15% (P＝0.000)，平均剂量为9.81 Gy vs.12.67 Gy (P＝0.004)；4例左侧乳腺癌患者的心脏V5 、V30分别为9.40% vs.15.23% (P＝0.014)、0.58% vs.5.95% (P＝0.074)，30 Gy等剂量线包括的心脏最大厚度为0.45 cm vs.1.35 cm (P＝0.003)，心脏的平均剂量为2.36 Gy vs.4.35 Gy (P＝0.044)。结论呼吸门控加全乳调强放疗改善了靶区的均匀性；降低了同侧肺、心脏的照射剂量和体积，可能降低晚期放射性肺炎及心血管事件的发生概率。

Abstract: ObjectiveTo evaluate the benefits of intensity-modulated radiotherapy （IMRT）with active breathing coordinator technique（ABC）compared with free breathing （FB） during treatment with conventional wedge-based whole breast irradiation (WBI) for the early stage breast cancer after breast-conserving surgery. MethodsEight patients (4 left-sided and 4 right-sided lesions) with stage T1~2N0M0 breast cancer were selected for this study. All patients had CT scans at FB and ABC. A dosimetric comparison of ABC-IMRT with FB-WBI was performed on each patient using three dimensional treatment planning. Dose volume histograms （DVH） and isodoses were used to compare the planning target volume（PTV）and organs at risks （OARs）,such as ipsilateral lung, and heart for the four left sided lesions. ResultsThe 95%PTV received 47.5 Gy/25 fractions; But V90% was 98.29% in ABC-IMRT method and 97.71% in FB-WBI method (P＝0.041); V105%was 54.54% vs. 72.22% (P＝0.035); V110% was 11.71% vs. 30.69% (P＝0.014) respectively in two methods. The percentage of volume receiving more than 20 Gy（V20）of ipsilateral lung for ABC-IMRT decreased from 22.20% to 17.89% (P＝0.000) compared with FB-WBI; and V30 from 18.15% to 14.39% (P＝0.000); The mean lung dose from 12.67 Gy to 9.81 Gy (P＝0.004). The percentage of V5 of heart for the four left sided patients for ABC-IMRT decreased from 15.23% to 9.40% (P＝0.014) compared with FB-WBI; V30 from 5.95% to 0.58% (P＝0.074); The thickness which was involved by the isodose of 30 Gy from 1.35 cm to 0.45 cm (P＝0.003).The mean heart dose from 4.35 Gy to 2.36 Gy (P＝0.044). ConclusionABC-IMRT improves dose homogeneity and significantly reduces the lung and heart irradiated volume and dose, thus possibly lessens the radiation injury to lung and heart.

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