全乳腺放疗野中野调强技术的三种设计方法对比

目的]优化全乳腺放疗时野中野调强技术的设计方法。方法]选取乳腺癌保乳术后患者10例．用野中野调强技术设计全乳腺放疗计划，每例患者分别用完全正向法（正向法）、完全正向加楔形板补偿法（正楔法）和正向加逆向直接射野优化（DMPO）法（正逆法）设计三个治疗计划并进行对比。结果]只有正逆法的计划靶区（P1rV）剂量分布能达到目标要求（平均剂量5000cGy，均匀性为±5％），其覆盖99％靶区体积的剂量为4753±28cGy，接受高于5250eGy剂量的靶区体积为0．2％，剂量不均匀性指数为1．092±0．005，均明显优于正向法和正楔法（P〈0．05）。三种方法中同侧肺、左心室和对侧乳房的受量无明显差异。结论]正向加DMPO的正逆法得到的剂量分布最好，正向加楔形板法产生的照射野最为简单。

Comparison of Three Techniques in Whole Breast Irradiation with Field-in-field Intensity Modulated Radiotherapy

Purpose] To optimize the technique of whole breast irradiation with field-in-field inten- sity modulated radiotherapy （IMRT）. Methods ] Ten cases with breast cancer undergoing breast conserving surgery enrolled in this study. Three field-in-field IMRT plans by means of forward, forward plus wedge compensation and forward plus inverse direct machine parameter optimization （DMPO） were carried out respectively for each case. The dose distribution were compared. Results ] Only the forward plus DMPO plan matched the goal for PTV （ mean dose： 5000cGy, heterogeneity：＋5%）. The dose covering 99% PTV was 4 753＋28cGy, the volume received 5 250cGy or more doses was 0.2% and heterogeneity index was 1.092＋0.005 in forward-DMPO plan. The dose distribution of forward- DMPO plan was superior to that of forward plan and forward-wedge plan （P〈0.05）. There was no significant difference of receiving dose among ipsilateral lung, contralateral breast and left ventrlcle in the three techniques. Conclusions ] The process of forward plus DMPO produced best dose distribution. Forward plus wedge compensation was the simplest method to produce reasonable dose distribution.