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目的:比较局部晚期贲门癌三维适形放疗(3D-CRT)与调强放疗(IMRT)对靶区剂量分布及周围正常组织的影响,为临床应用提供参考。方法:选择晚期贲门癌患者11例,每例患者分别设计3D-CRT计划及IMRT计划,IMRT计划采用7个共面等间距射野。以54Gy为PTV的处方剂量,用等剂量曲线和剂量体积直方图(DVH)评价两种治疗计划对靶区剂量分布及周围正常组织的影响。结果:两种计划相比,IMRT计划靶区的适形指数和均匀性指数分别为0.762±0.045和1.113±0.017,3D-CRT计划靶区的适形指数和均匀性指数分别为0.663±0.043和1.142±0.029,P<0.05,IMRT计划优于3D-CRT计划。3D-CRT计划与IMRT计划PTV的V100分别为(95.85±2.07)%和(96.72±1.48)%,P=0.024;D100分别为(51.08±0.65)和(51.83±0.44)Gy,P=0.000,IMRT计划优于3D-CRT计划。而PTV的V95及D95两种计划相比差异无统计学意义,P>0.05。IMRT计划的左肾V15、肝脏V20、肝脏平均受量和脊髓最大受量分别为(19.05±3.66)、(29.79±4.70)、(12.65±1.71)和(37.54±1.66)Gy,3D-CRT计划的分别为(22.99±4.14)、(38.14±5.91)、(15.09±2.06)和(41.19±1.72)Gy,IMRT计划明显低于3D-CRT计划,P<0.05;而右肾V15、心脏平均受量IMRT计划略高于3D-CRT计划,差异无统计学意义,P>0.05。结论:对于局部晚期贲门癌,IMRT计划较3D-CRT计划有明显的靶区剂量分布优势,同时可以减少脊髓、肝脏和左肾的器官受照剂量。
Objective: To compare the effects of three-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiotherapy (IMRT) on dose distribution and surrounding normal tissues in locally advanced cardia cancer, so as to provide reference for clinical application. Methods: Eleven patients with advanced cardia cancer were selected. 3D-CRT plan and IMRT plan were designed for each patient. IMRT plans to use seven coplanar equidistant fields. The effects of the two treatment schedules on the dose distribution in the target area and the surrounding normal tissue were evaluated using an isodose curve and a dose-volume histogram (DVH) at a prescribed dose of 54 Gy for PTV. Results: Compared with the two plans, the conformal index and the uniformity index of IMRT targets were 0.762 ± 0.045 and 1.113 ± 0.017, respectively. The conformal index and uniformity index of the target area of D-CRT were 0.663 ± 0.043 and 1.142 ± 0.029, P <0.05, IMRT plan is superior to 3D-CRT plan. The V100 of PTV was (95.85 ± 2.07)% and (96.72 ± 1.48)%, respectively, P = 0.024 for 3D-CRT and IMRT plans, and was 51.08 ± 0.65 and 51.83 ± 0.44 Gy, P = 0.000 for D100, IMRT plans outperform 3D-CRT plans. There was no significant difference between PTV V95 and D95 (P> 0.05). The IMRT plans for left kidney V15, liver V20, mean liver volume and maximum spinal cord volume were (19.05 ± 3.66), (29.79 ± 4.70), (12.65 ± 1.71) and (37.54 ± 1.66) Gy, respectively. (22.99 ± 4.14), (38.14 ± 5.91), (15.09 ± 2.06) and (41.19 ± 1.72) Gy, respectively. The IMRT plan was significantly lower than the 3D-CRT plan, P <0.05; The amount of IMRT plan slightly higher than the 3D-CRT plan, the difference was not statistically significant, P> 0.05. CONCLUSIONS: For locally advanced cardia cancers, the IMRT program has a significant target-dose distribution advantage over the 3D-CRT plan and at the same time reduces the organ-exposure dose of the spinal cord, liver and left kidney.