胸上段食管癌三维适形和调强放疗剂量学对比研究

Comparison of dose distributions between conformal and intensity-modulated radiotherapy for the upper esophageal carcinoma

目的筛选胸上段食管癌不同适形和调强放疗计划优选方案。方法8例胸上段食管癌CT模拟后参考食管钡餐造影和食管镜结果勾画GTV，按统一标准外扩CTV和PTV，实施3、4、6个野适形治疗计划和3、4、5、7、9、11个野IMRT计划和s-IMRT计划，以95％PTV体积获得6000cGy处方剂量进行归一，分析各治疗计划靶区剂量分布和危及器官受量，进行剂量学对比研究。结果3套适形计划之间，PTV剂量参数和体积参数均相近（P〉0．05）；6个野适形计划全肺V20高于4个野（P〈0.05），3、6个野适形计划MLD也高于4个野（P〈0.05）。6套调强治疗计划中，3个野IMRT计划PTV D100低于9、11个野IMRT计划（P〈0.05）；4个野IMRT计划IV高于9、11个野IMRT计划（P〈0.05）；9、11个野IMRT计划PTV适形指数CI、剂量参数D95、体积参数V100和V95较5、7个野IMRT和s-IMRT计划无明显优势（P〉0.05）；各IMRT计划之间危及器官受量相近（P〉0．05）。胸上段食管癌4个野适形计划PTV CI、PTV剂量参数和体积参数均低于5、7个野IMRT计划和s-IMRT计划（P〈0.05）；4个野适形计划全肺V20均高于5、7个野IMRT计划和s-IMRT计划（P〈0.05）。结论胸上段食管癌三维适形放疗中4个野适形计划可为优选方案，调强放疗中5、7个野IMRT计划和s-IMRT计划可为优选方案。胸上段食管癌5、7个野IMRT计划和s-IMRT计划优于4个野适形计划。

Objective To evaluate the optimized conformal and IMRT plans for the upper esophageal carcinoma. Methods Eight patients with upper esophageal carcinoma underwent CT simulation. GTV was contoured on the CT image, referring the esophagogram and endoscopy simultaneously, then CTV and PTV were also defined using the same criteria. Different conformal radiotherapy plans consisting of 3 fields （F）, 4F or 6F, IMRT plans consisting of 3F, 4F, 5F, 7F, 9F or 11F, and a simplified IMRT （s- IMRT） plan were designed for these patients. The minimum prescription dose that 95% of PTV volume received was 6000 cGy. Dose distributions of the PTV and OARs in different 3DCRT and IMRT plans were compared and the optimized plans for the upper esophageal carcinoma were then recommended. Results Dose and volume parameters of PTV were similar among the 3DCRT plans （ P 〉 0.05 ）. 4F 3DCRT plan reduced lung V20 as compared to 6F plan （P 〈 0.05 ） , and mean lung dose （MLD） of 3F and 6F 3DCRT plans were higher than that of 4F plan （P 〈0.05）. PTV D100 of 3F IMRT plan was lower than that of 9F and 11F plans （P 〈0.05）. IV of 4F IMRT plan was larger than that of 9F and 11F IMRT plans （P 〈 0.05 ）. PTV dose and volume parameters of the 9F IMRT and 11F IMRT were similar comparing with 5F, 7F and s- IMRT plans, and OARs dose was also similar among IMRT plans （ P 〉 0.05 ）. PTV CI, D100, D95 , V100 and V95 of the 4F 3DCRT plan were all lower than those of 5F, 7F and s-IMRT plans（P 〈 0.05 ）. 5F, 7F and s- IMRT plans reduced lung V20 as compared to 4F 3DCRT plan （ P 〈 0.05 ）. Conclusions For the upper esophageal carcinoma, 4F 3DCRT plan is recommended among the 3DCRT plans. 5F, 7F and s-IMRT plans are recommended among the IMRT plans,which are superior than 4F 3DCRT plan.