乳腺癌术后胸壁切线野与容积弧形调强技术的剂量学比较

Dosimetric comparison of traditional tangential fields and volumetric modulated arc therapy techniques in adjuvant chest wall radiotherapy planning for patients with breast cancer

目的:分析比较乳腺癌术后胸壁辅助放疗采用容积弧形调强技术与传统的胸壁切线野的剂量学差异。方法:随机选择需要放射治疗的乳腺癌患者10例,左右侧各5例,采用Eclipse计划系统为每位患者分别设计传统的胸壁切线野与容积弧形调强两套放射治疗计划,处方剂量均为DT50Gy/25次。用剂量体积直方图(DVH)比较靶区、心脏和肺受照射剂量和体积等参数的差异。结果:2种技术均能满足胸壁靶区剂量分布要求。与常规切线野相比,容积弧形调强技术使左侧乳腺癌患者的心脏平均V30由15.87%减少到1.58%(P=0.00),心脏平均V10由22.41%增加到37.82%(P=0.00);左肺平均V20由25.72%减少到11.35%(P=0.00),左肺平均V30由22.79%减少到4.23%(P=0.00)。右侧乳腺癌患者右肺平均V20由28.23%减少到13.55%(P=0.00),右肺平均V30由25.31%减少到5.77%(P=0.00),右肺平均V10由33.26%增加到42.08%(P=0.01)。无论左、右侧乳腺癌,容积弧形调强技术对于身体的低剂量照射范围均大于传统切线野。结论:乳腺癌术后胸壁辅助放疗采用容积弧形调强技术相对于传统的胸壁切线野,能明显减少心脏和肺的高剂量受照体积,却增加了低剂量区范围。

OBJECTIVE： To compare traditional tangential fields and volumetric modulated arc therapy techniques in adjuvant chest wall radiotherapy planning for patients with breast cancer, and improve technology to reduce normal tissue radiation exposure. METHODS： Ten consecutive cases of breast cancer （5 cases for each side） who received post-mastectomy chest wall irradiation were selected for this study. Dosimetric comparison of tangential fields planning with RapidArc planning was performed in each patient,using Eclipse treatment planning system. The total prescribed dose was 50 Gy/25 fractions for both sets of planning. Dose-volume histogram （DVH） parameters were used to compare the dosimetry of the target, heart and lung. RESULTS： Treatment plans generated using volumetric modulated arc therapy resulted in chest wall coverage similar to that of conventional tangential fields. The mean values of V30 for heart of left breast cancer patients decreased from 15.87% to 1.58% （P=0.00） ,the mean values of V10 for heart increased from 22.41% to 37.82% （P=0.00）,the mean values of V2o for left lung decreased from 25.72% to 11.35%（P=0.00）,the mean values of V30 for left lung decreased from 22.79% to 4.23% （P=0.00）. The mean values of V20 for right lung of right breast cancer patients decreased from 28.23% to 13.55% （P=0.00）,the mean values of V30 for right lung decreased from 25.31% to 5.77% （P= 0.00） ,the mean values of V10 for for right lung increased from 33.26% to 42.08%/oo （P = 0.01）. CONCLUSION： In comparison with traditional tangential field planning, volumetric modulated arc therapy planning can significantly reduce the high-dose exposure of heart and lung,but increase the low-dose bath.