颈及上胸段食管癌同步加量调强放疗技术的比较分析

摘要

目的：比较分析颈及上胸段食管癌不同射野数目同期加量调强放疗（SIB-IMRT）技术的剂量学参数，探讨优选方案。方法对24例食管癌患者分别设计3、5、7、9四种不同照射野数的 SIB-IMRT 计划。 PTV-G 为大体肿瘤体积（GTV）外放1cm，PTV-C 为临床靶体积（CTV）外放1cm，处方剂量分别为2．15 Gy／ f 和2 Gy／ f，28次， DT 60．2 Gy 和56 Gy。通过剂量体积直方图（DVH）评估各靶区和危及器官的剂量学参数。结果 PTV-G 3、5、7、9野 SIB-IMRT 计划的靶区适形性指数（CI）和不均匀性指数（HI）分别为0．33、0．55、0．77、0．80和1．09、1．07、1．07、1．05，差异均有统计学意义（P＜0．05）；PTV-C 3、5、7、9野 SIB-IMRT 计划的靶区 CI 和 HI 分别为0．69、0．71、0．72、0．79和1．22、1．13、1．075、1．073，差异均有统计学意义（P＜0．05）。3、5、7、9野脊髓最大剂量分别为4511．27、4288．31、4224．60和4201．43 cGy，差异有统计学意义（P＜0．05）。随着设野数目的增加，两肺的 V5值增加，9野计划明显高于7野计划，分别为44．56％和32．36％（P＜0．05）；V20减小，9野计划与7野计划两者相似，分别为19．28％和19．65％（P＞0．05）。结论7野 SIB-IMRT 计划靶区剂量均匀，适形度高，对肺等重要器官的保护最佳，是颈段及上胸段食管癌 SIB-IMRT 治疗中优选的方案。%Objective To compare the dosimetric parameters of 4 simultaneous integrated boost intensity-modulated radiother-apy (SIB-IMRT) treatment plans with different beams. Methods Four SIB-IMRT treatment plans with different beams of 3, 5, 7 and 9 were designed for twenty-four eligible patients with cervical and upper thoracic esophageal carcinoma. PTV-G and PTV-C were de-fined as the GTV and CTV plus 10 mm in all directions, which were delivered simultaneously to 60. 2 Gy and 56 Gy in 28 fractions, re-spectively. Compared and evulated the dosimetric parameters of planning target volums and organs at risk(OARs) through the DVH di-agram. Results The values of conformity index (CI) and heterogeneity index (HI) of four SIB-IMRT treatment plans with different beams of 3, 5, 7 and 9 were 0. 33,0. 55,0. 77,0. 80 and 1. 09,1. 07,1. 07,1. 05 in PTV-G,with significant difference(P<0. 05). The values of CI and HI of SIB-IMRT treatment plans with four different beams were 0. 69, 0. 71,0. 72,0. 79and 1. 22,1. 13,1. 075,1. 073 in PTV-C,with significant difference (P<0. 05). The values of maximal dose of spinal cord were 4511. 27,4288. 31, 4224. 60 and 4201. 43 cGy in 3,5,7,9-beams SIB-IMRT plans (P<0. 05). With increased beam numbers, the V5 increased and the V20 decreased. The 9-beams plan had significantly increased V5 and nonsignificantly decreased V20 compared to the 7-beams plan. The V5 and V20 were 44. 56% and 19. 28% in 9-beams plan and 32. 36% and 19. 65% in 7-beams plan. Conclusion 7-beams SIB-IMRT plan was the pre-ferred technique in cervical and upper thoracic esophageal carcinoma with uniform target dose and high degree conformity, which could provide the best protection to the lung and other vital organs.