调整等中心技术在乳腺癌三维适形放疗中的应用

目的：比较乳腺癌放疗中，采用传统切线野、适形和调整等中心三种照射技术对改善靶区剂量均匀性和保护正常组织的作用．以改进放射治疗方法。方法：随机选择6位行全乳放疗的乳腺癌患者，为每位患者各设计上述的三种照射技术的治疗计划．给予90％PTV靶体积45Gy的处方剂量，分别比较它们的靶区平均剂量、剂量均匀性指数、重要器官平均剂量．以及剂量分布图和DVH图。结果：三种技术靶区剂量均匀性方差分析差异具有统计学意义（P〈0．01），调整等中心技术的靶区均匀性最好，而传统的切线照射技术最差。三种技术在保护重要器官上其差异也具有统计学意义（P〈0．01），调整等中心技术对肺组织保护得最好。结论：通过调整靶区等中心能够提高靶区剂量均匀性，有效降低重要器官的受量，提高乳腺癌的控制率，而且此法简单易行，值得推广。

Application of Changing the Isocenter Position Technique for Breast Cancer on CRT

Objective： To compare the benefit of three techniques, including conventional technique with two wedged tangential fields, CRT and changing the isocenter position, in target dose uniformity and normal tissue sparing for breast cancer. Methods： For each of 6 randomly chosen patients, 3 plans were designed for three different irradiation techniques with a prescribed dose of 45Gy to at lease 90% of PTV. The following parameters of each plan were compared： average dose in target, dose uniformity in target, average dose in organ at risk, and the dose distribution line, dose-volume histogram（DVH）. Results： The dose uniformity differences in target for three techniques were significant, P〈 0.01. The technique of changing the isocenter position had the best uniformity. About the normal tissue sparing, the differences were significant, P〈0.01. The lung protection for the technique of changing the isocenter position was better than the other two techniques. Conclusions： Changing the isocenter position can enhance the dose uniformity in target, reduce the dose of OARs, and improve the control on the breast tumor. The method is easy, valuable and practical.