简单调强技术在胃癌术后放疗中的应用研究

目的研究简单调强放射治疗（sIMRT）技术在胃癌术后放射治疗中的剂量学特点，为临床提供参考。方法选取2012年2—6月间在南京医科大学附属淮安第一医院接受治疗的12例胃癌术后患者，分别设计三维适形放疗（3D-CRT）、5野调强放射治疗（IMRT）计划和5野简单调强放射治疗（sIMRT）计划，其中3D．CRT采用上下分野照射，调强放疗均选取20°、80°、180°、280°和34005个照射野。应用剂量体积直方图（DVH）比较3种计划的适形度指数、不均匀性指数、正常组织受照剂量特点、机器治疗总跳数及治疗总时间。结果sIMRT和IMRT计划适形度优于3D—CRT计划，但不均匀性亦甚于3D．CRT计划，差异有统计学意义（均P〈0．05）。在不同的放疗剂量下，sIMRT计划受照射的肝脏和双肾体积百分比均低于3D．CRT计划（均P〈0．05），与IMRT计划相近（均P〉0．05）。sIMRT计划的机器总跳数和总治疗时间均少于IMRT计划和3D—CRT计划。结论sIMRT技术和IMRT技术用于胃癌术后放疗，其剂量分布明显优于3D—CRT技术；但sIMRT技术治疗时间最短，在临床应用具有更便捷的优势。

Application of simplified intensity modulated radiation therapy in gastric cancer after operation

Objective To elucidate the application and the dosimetry characteristic of the simplified intensity modulated radiation therapy （sIMRT）for gastric cancer after operation, and to compare the dose distribution with intensity modulated radiation therapy （IMRT） and three-dimension conformal radiation therapy （3D-CRT）. Methods Twelve patients with gastric cancer after operation were enrolled in this study. 3D-CRT plan, 5-field IMRT plans（20°, 80°, 180°, 280°, 340°） and 5-field sIMRT plans（20°, 80°, 180°, 280°, 340°） were performed for each patient. The conformal index （CI）, heterogeneity index （HI） of the planning target volume （PTV） and the dose of normal organs were analyzed with the dose volume histogram （DVH）. The total MU and treatment time were also compared. Results The sIMRT and IMRT plans had comparable CI （sIMRT〉IMRT〉3D-CRT）, and showed better dose comformity but worse homogeneity than 3D-CRT. The percentage of volume receiving 20 Gy, 25 Gy, 30 Gy and 40 Gy by liver were significantly lower in sIMRT than that in 3D-CRT, and comparable to IMRT. All the dose volumes to kidneys with sIMRT were still significantly lower as compared to 3D- CRT, and comparable to IMRT. The sIMRT plan was better than IMRT plan in total MU and treatment time. Conclusions sIMRT has comparable dose distribution in patients with gastric cancer to IMRT, but is significantly better than 3D-CRT. Treatment time of sIMRT is the shortest. So sIMRT technique can be applied more simply.