Dosimetric investigation of non-coplanar field technology in static intensity-modulated radiation therapy for gastric carcinoma

Objective To compare the dosimetric characteristics of non-coplanar and coplanar field technology in static intensity-modulated radiotherapy of gastric cancer patients, so as to provide a reference for clinical radiotherapy plan selection. Methods Thirty-six patients with gastric cancer were selected to receive intensity-modulated radiotherapy in Huanggang Central Hospital, which was designed plan A and B. Group A used 7-field coplanar technology, while Group B used 7-fleld non-coplanar technology. We compared the differences of the optimized monitor unit, the dosimetry of organs at risk and target areas between group A and group B. Results Both group A and B could meet the requirements of doctors. The homogeneity index (0.14 ± 0.02), the conformity index (0.98 ± 0.01), D min (4 315.21 ± 16.74) cGy, D mean (4 679.28 ± 28.39) cGy and D max (4 952.30 ± 33.26) cGy of target areas in group B were better than those of group A. Moreover, the monitor unit of group B was much lower than that of group A, and the difference was statistically significant ( P < 0.05). The D max, D mean, V 15, V 20 and V 30 of the left and right kidneys in group B were lower than those of group A. The D max (3 408.57 ± 46.03) cGy, D mean (1 250.32 ± 14.27) cGy and V 20 (44.91% ± 6.67%) of spinal cord and the D max (3 408.57 ± 46.03) cGy, D mean (1 720.55 ± 17.42) cGy, V 20 (25.31% ± 7.78%) and V 30 (18.52% ± 1.56%) of small intestine were also lower than those of group A. The differences were statistically significant ( P < 0.05). Conclusion The non-coplanar field radiation plan has more advantages in terms of target dose distribution and protection of organs so that it can be more considerably used in the process of planning and design. 摘要： 目的 通过比较非共面射野与共面射野计划在胃癌静态调强中的剂量学特点, 为临床放疗计划选择提供依 据。 方法 选取黄冈市中心医院接受调强放射治疗的胃癌患者 36 例, 每名患者均设计A、B 2 组计划, A 组采用 7 野 共面技术, B 组采用 7 野非共面技术, 比较 A 组和 B 组优化后机器跳数、危及器官和靶区的剂量学差异。 结果 A、B 两组计划均能满足医生要求, B 组靶区均匀性指数 HI (0.14 ± 0.02)和适形度指数 CI (0.98 ± 0.01), 靶区 D min (4 315.21 ± 16.74) cGy, D mean (4 679.28 ± 28.39) cGy 和 D max (4 952.30 ± 33.26) cGy 均优于 A 组, 且 B 组机器跳数更 少, 差异有统计学意义 ( P < 0.05)。B 组左右侧肾脏 D max、 D mean、 V 15、 V 20 和 V 30均低于A组, 脊髓的 D max (3 408.57 ± 46.03) cGy、 D mean (1 250.32 ± 14.27) cGy 和 V 20 (44.91% ± 6.67%)以及小肠的 D max (3 408.57 ± 46.03) cGy、 D mean (1 720.55 ± 17.42) cGy、 V 20 (25.31% ± 7.78%) 和 V 30 18.52% ± 1.56%)也均低于 A 组, 差异有统计学意义 ( P < 0.05)。 结论 非共面射野计划在靶区剂量分布和危及器官保护上更优, 计划设计过程中可以更多的考虑非共面布野技术。