单中心上下半野技术在胸中上段食管癌放射治疗中的剂量学分布

Dose distribution of mono- isocenter irradiation technique in radiotherapy for the upper and middle thoracic segment esophageal carcinoma

目的:单中心上下半野照射为胸中上段食管癌放射治疗提供一种更好的照射方式。通过比较6种不同治疗方案的剂量学分布,比较出靶区覆盖度高、均匀性好、适形度高、正常组织受照量又小的治疗方式。方法:选择20例胸中上段的食管癌病人,采用6种治疗方案,A方案为常规5野适形照射,B方案为常规5野调强照射,C方案为常规3野调强照射;单中心上下半野照射也分3种,D方案为上段5野调强照射,下段3野适形照射;E方案为上段5野调强照射,下段3野调强照射;F方案为上段5野调强照射,下段5野调强照射。比较6种不同方案的靶区受照剂量和正常组织的受照剂量。结果:在6种方案中,单中心上下半野技术的3种方案的靶区覆盖度很好,其中D、E两方案不光肺的低剂量区指标比较低,而且平均肺剂量也较低;E方案的适形指数要高于D方案。结论:对胸中上段食管癌来说,单中心上下半野照射的D、E方案是剂量学比较有优势的方案,能够最大程度地提高靶区剂量,而又让肺组织的受照剂量降到最低。

Objective To select a treatment with higher coverage of target volumes, better uniformity, higher conformity and smaller normal tissue radiation dose by comparing the dose distribution of 6 different treatments. And the mono-isocenter irradiation technique can provide a better way of irradiation in the radiotherapy for the upper and middle thoracic segment esophageal carcinoma. Methods The 20 patients with upper and middle thoracic segment esophageal carcinoma were selected, undergoing 6 different kinds of treatments. In these treatments, the conventional conformal intensity modulated radiation therapy （IMRT） was divided into three programs： A program for the conventional 5 field conformal irradiation, B program for conventional 5 field intensity modulated radiation, and C program for conventional 3 field intensity-modulated radiation. And the mono-isocenter irradiation technique was also divided into three kinds, D program was 5 field IMRT in the upper target, 3 field conformal irradiation in the down target, and E program was 5 field IMRT in the upper target, 3 field IMRT in the down target, and F program was 5 field IMRT in the upper target, 5 field conformal irradiation in the down target. The radiation dose for target volumes and normal tissues were compared between these 6 kinds of treatments. Results Among these 6 kinds of treatments, the 3 kinds of treatments applied mono-isocenter irradiation technique had a good coverage of target volumes. Moreover, the lung low-dose area indexes of D and E treatments plan were lower than those of other plans and the lung MLD of them were also lower. But the conformal index of E treatment plan was higher than that of D. Conclusion For the upper and middle thoracic segment esophageal carcinoma, D and E treatments are two treatments with relative advantages, which can to the greatest extent improve dose for target volumes, and allow normal tissue radiation doses to minimize.