摘要目的:研究基于Halcyon 2.0和Truebeam两种加速器设计的容积调强弧形治疗（VMAT）计划，在患者不同部位的剂量学质量和计划复杂度差异。方法:回顾性选取头颈部、胸部、腹部、盆腔四种部位的Halcyon 2.0 VMAT计划49例，并以相同优化参数重新设计Truebeam VMAT计划，比较两种计划的剂量学和复杂度指标差异， P<0.05表示差异有统计学意义。 结果:对于靶区，Halcyon 2.0在头颈部和胸部计划中具有较优的均匀性指数（HI）和适形性指数（CI），在腹部计划中具有较优的D 98%和CI，在盆腔计划中具有较优的D 2%。对于危及器官，Halcyon 2.0在胸部计划中的双肺D 20%、D mean和心脏D mean均低于Truebeam（ P值均<0.05）。对于复杂度指标，Halcyon 2.0头颈、腹部和盆腔计划的中位平均子野面积变化率（AAV）分别为0.414、0.425和0.432，优于Truebeam的0.385、0.368和0.361；在腹部和盆腔计划中，Halcyon 2.0的中位调制复杂度分数（MCS）分别为0.320和0.303，优于Truebeam的0.268和0.282（ P值均<0.05）；Halcyon 2.0所有部位计划的中位小孔径分数（SAS）均优于Truebeam，且中位计划平均射野面积（PA）均大于Truebeam（ P值均<0.05）。 结论:基于Halcyon 2.0和Truebeam两种加速器设计的VMAT计划，在剂量学质量上相当，部分情况下前者略优，但是由于前者较低的计划复杂度，使其在临床应用中具有相对优势。

abstractsObjective:To analyze the differences in dosimetric quality and plan complexity of volumetric modulated arc therapy (VMAT) plans based on Halcyon 2.0 and Truebeam for different treatment sites of the patients.Methods:Halcyon 2.0 VMAT plans in head & neck, chest, abdomen, and pelvis treatment sites of 49 cases were retrospectively selected and the VMAT plans were re-designed based on Truebeam with the same optimization parameters. The differences in dosimetric metrics and plan complexity between the two types of plans were compared and analyzed. P<0.05 was considered as statistically significant. Results:In terms of PTV, Halcyon 2.0 plans showed better homogeneity index (HI), conformal index (CI) in the head & neck and chest. Besides, Halcyon 2.0 plans yielded better D 98% and CI in the abdomen and better D 2% in the pelvis. For organs at risk (OAR), the D 20% and D mean of bilateral lungs, and D meanof heart for Halcyon 2.0 plans in the chest were lower than those for Truebeam plans (all P<0.05). For the complexity metrics, the median average aperture area variability (AAV) of Halcyon 2.0 plans in the head & neck, abdomen and pelvis were 0.414, 0.425 and 0.432, which were better than 0.385, 0.368 and 0.361 of Truebeam plans in the corresponding sites, respectively. In the abdomen and pelvis, Halcyon 2.0 plans showed better median modulation complexity score (MCS) than Truebeam plans (0.320 vs. 0.268, 0.303 vs. 0.282; both P<0.05). The median small aperture score (SAS) for all plans of Halcyon 2.0 were better than that of Truebeam plans (all P<0.05), and the median plan average beam area (PA) of all plans of Halcyon 2.0 were larger than that of Truebeam plans (all P<0.05). Conclusions:Compared with conventional fractionated VMAT plans based on Halcyon 2.0 and Truebeam, Halcyon 2.0 plans have similar or even better dosimetric quality. However, Halcyon 2.0 plans have lower plan complexity, which makes it an advantage in clinical application.