VMAT和IMRT技术在直肠癌患者术后放疗中的剂量学比较

Dosimetric comparison of VMAT and IMRT in postoperative radiotherapy for rectal cancer patients

摘要

目的：比较分析容积旋转调强放射治疗（VMAT）和固定野调强放射治疗（IMRT）技术在直肠癌患者术后放射治疗中的剂量学。方法：选取37例直肠癌术后患者，进行CT模拟定位，靶区和危及器官勾画，在同一CT图像上用治疗计划系统进行IMRT和VMAT计划设计，处方剂量给予50 Gy/25次，使用相同的剂量约束条件，比较两种计划的靶区平均剂量、适形度指数（CI）、均匀性指数（HI）、危及器官受照剂量、机器跳数及治疗时间。结果：两种治疗计划均能满足临床剂量要求，VMAT计划的靶区平均剂量略高于IMRT计划，HI、CI均优于IMRT，差异有统计学意义（P<0.05）。IMRT和VMAT计划中重要的危及器官（膀胱和股骨头）受照剂量比较差异无统计学意义（P>0.05）。VMAT计划的机器跳数少于IMRT计划，预估出束时间短于IMRT计划，差异有统计学意义（P<0.05）。结论：VMAT和IMRT技术应用于直肠癌患者术后放射治疗中均可满足临床要求，VMAT计划可以显著减少机器跳数，缩短治疗时间。

Abstract

Objective To compare and analyze dosimetric differences of volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) in postoperative radiotherapy for patients with rectal cancer. Methods Thirty-seven patients with rectal cancer were enrolled. CT simulation was performed, followed by target volume and organs-at-risk delineation. IMRT and VMAT plans were generated on the same CT image using the treatment planning system, with a prescribed dose of 50 Gy in 25 factions and the identical dose constraints. The two plans were compared in terms of mean target dose, conformity index (CI), homogeneity index (HI), doses to organs-at-risk, monitor unit, and delivery time. Results Both treatment plans met clinical dose criteria. Compared with IMRT, VMAT achieved a slightly higher mean target dose and superior HI and CI, with statistically significant differences (P<0.05). No significant inter-plan differences were observed in the doses delivered to important organs-at-risk (bladder and femoral heads) (P>0.05). In addition, VMAT required fewer monitor units and shorter delivery time relative to IMRT (P<0.05). Conclusion Both VMAT and IMRT satisfies the clinical requirements for postoperative radiotherapy of patients with rectal cancer. VMAT can significantly reduce monitor unit and shorten delivery time.

关键词

直肠癌 / 放射治疗 / 容积旋转调强 / 固定野调强 / 剂量学

Key words

rectal cancer / radiotherapy / volumetric modulated arc therapy / intensity-modulated radiotherapy / dosimetry

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基金资助

江苏省卫生健康委科研项目(Z2023A071)