独立准直器调强技术在鼻咽癌放射治疗的应用评估

Evaluation of Jaws-only intensity-modulated radiation therapy for nasopharyngeal carcinoma

目的利用直接射野优化技术和加速器独立准直器进行调强放射治疗计划设计及测试运行,探索其用于鼻咽癌临床治疗应用的可行性。方法使用一种基于直接射野优化技术的商业化治疗计划系统,对10例鼻咽癌患者分别设计独立准直器调强(JO-IMRT)和多叶准直器调强(MLC-IMRT)治疗计划。比较两种计划的靶区剂量适形度和均匀性参数,以及剂量监测器跳数和执行时间等差别。结果两种计划均能满足鼻咽癌简单调强的临床剂量要求,JO-IMRT与MLC-IMRT的计划靶区剂量适形度指数分别为0.941±0.015和0.981±0.013(P<0.001),肿瘤靶区的剂量均匀性指数分别为0.904±0.012和0.915±0.019(P>0.05),前者的计划质量略差于后者;简单调强条件限制下两种计划的子野数接近,但总剂量监测器跳数平均值分别为474.3和419.6(P<0.05),执行时间的平均值分别为8.0与7.5min(P<0.01),JO-IMRT的执行效率稍差于MLC-IMRT。结论 JO-IMRT可以满足较简单的鼻咽癌调强治疗要求。尽管其计划质量与执行效率略差,JO-IMRT对没有配置多叶准直器的放疗单位作为MLC-IMRT的替代方法具有实际应用价值。

Objective To investigate the feasibility and efficiency of jaws-only intensity-modulated radiation therapy（JO-IMRT） in treatment of nasopharyngeal carcinoma（NPC） using direct aperture optimization（DAO） technique and the independent jaws of linear accelerator.Methods Both JO-IMRT and MLC-IMRT were planed in 10 NPC cases.The differences in the target coverage and dose uniformity,as well as the total monitorunits and delivery times of the two IMRT plans were compared.Results All the tested plans met the clinical requirement of the designed simplified IMRT（sIMRT）.The conformal index（CI） of JO-IMRT and MLC-IMRT were 0.941？？.015 and 0.981？？.013,respectively（P0.001）,showing a minorsuperiority of MLC-IMRT.While controlling the total segment numbers to approach the limitation of sIMRT,the two therapies showed a total MU of 474.3 and 419.6（P0.05） with delivery times of 8.0 and 7.5 min（P0.01）,respectively.The efficiency of JO-IMRT was slightly lowerthan that of MLC-IMRT.Conclusion JO-IMRT can meet the sIMRT requirement in NPC treatment,and is feasible as an alternative treatment modality for the centers not equipped with MLC in their accelerators.