胃癌调强放疗中多叶光栅3种状态的剂量学比较

目的:通过比较胃癌调强放疗中多叶光栅（MLC）3种不同状态下放疗计划的剂量学差异，为临床放疗方案的选择提供参考依据。 方法:选取10例胃癌患者分别制定9野的锁野调强、分野调强和旋转小机头分野调强的治疗计划，比较机器跳数，靶区适形度、均匀性、Dmax、Dmean、V45，以及body、肝脏、小肠、脊髓和肾脏V5、V10、V20、V30、V40、V45、Dmax、Dmean等参数的剂量学差异。 结果:3种计划均可满足临床需求。锁野计划相比分野和旋转小机头分野调强计划在body的V5、V10、V20、V30均显著降低且差异具有统计学意义，同时对于肾脏、肝脏和小肠在某些低剂量区均有一定的降低且有统计学差异。对于body（计划靶区）的Dmax参数，分野计划稍微低于锁野和旋转小机头分野调强计划且差异具有统计学意义。 结论:锁野计划可以更好地保护危及器官，同时减少低剂量区。

Dosimetric comparison among split-field,fixed-jaw and rotating multi-leaf collimator in the radiotherapy of gastric carcinoma

Abstract: Objective To compare the dosimetric differences among split-field, fixed-jaw and rotating multi-leaf collimator (RMLC) used in intensity-modulated radiotherapy of gastric carcinoma for providing reference for the selection of treatment strategy. Methods Ten patients with gastric carcinoma was enrolled in this study, and 3 plans, namely fixed-jaw plan (9-field), split-field plan and RMLC plan, were designed for each patient. Several dosimetric parameters, including monitor units, the conformity index, homogeneity index, Dmax, Dmean, V45 of target areas, and the V5, V10, V20, V30, V40, V45, Dmax, Dmean of the body, liver, small intestine, spinal cord and kidneys were compared. Results All 3 plans met clinical requirements. The V5, V10, V20 and V30 of the body in fixed-jaw plan were significantly lower than those in split-field plan and RMLC plan, and meanwhile, there were some decreases in the low-dose volume of the kidney, liver and small intestine, with statistical differences. The Dmax of the body (planning target volume) in split-field plan was lower than that in fixed-jaw plan and RMLC plan, with statistical differences. Conclusion Compared with split-field plan and RMLC plan, fixed-jaw plan achieves a better organs-at-risk protection and reduces low-dose volume.