楔形板在胸上段食管癌放疗中对TPS剂量分布影响探讨

目的：探讨楔形板在胸上段食管癌放疗应用中对TPS剂量分布的影响。方法：对胸上段食管鳞癌患者行螺旋CT扫描，获取病灶及其周围组织的三维数据，在TPS中设计加用头足向45°楔行板和不加楔形板的两个计划，计算并比较二者剂量体积直方图。结果：尽管两个计划形成的靶区剂量平均值非常接近，但剂量分布的均匀性有显著差别，不加楔形板时靶区剂量标准差为6．31；在前野加45°楔行板后靶区剂量标准差为4．45，显示采用楔形板后靶区剂量的离散性显著减小，即靶区剂量的分布更加均匀。结论：在常规照射方式的射野中加入楔形板来改善胸上段食管癌照射剂量分布是一种简单有效的方法。

Study on TPS Dose Distribution of Radiation Therapy with Wedge for Upper-thoracic Esophageal Cancer

Objective To study the TPS dose distribution of the radiation therapy with wedge for upper- thoracic esophageal cancer. Methods Adopting spiral CT scanning, three dimensional data of the focus of infection and the other tissues were acquired. The radiotherapy plans with 45° wedges and without wedge were designed in TPS. The dose-volume histogram were calculated and compared.Results Although the average of dose of irradiated target was very close in the two plans, but there was remarkable difference in the dose uniformity. The Std （standard deviation） of dose in irradiated target was 6.31 in plan without wedge, and it was 4.45 in plan with the 45° wedge. The results show that the dose distributions of irradiated target are optimized by using the wedge. Conclusion It is a simple and effective method to use wedge for improving dose distribution in the radiation therapy for upper-thoracic esophageal cancer.