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目的 比较胸上段食管癌容积旋转调强放疗(VMAT)和静态调强放疗(IMRT)的剂量学差异.方法 选择30 例局部晚期胸上段食管癌患者,分别设计VMAT和IMRT两套放疗计划,比较它们的计划靶区(PTV)剂量分布、适形度指数(CI)、均匀性指数(HI)、危及器官(OAR)受量、机器跳数(MU)和有效治疗时间.结果 两组计划均能满足临床剂量学要求.计划靶区1(PTV1):VMAT的D2和HI值低于IMRT(P＜0.05);VMAT的CI值好于IMRT(P＜0.05).两者的D50、D98、V110和CI值差异无统计学意义(P＞0.05).计划靶区2(PTV2):VMAT组D2和HI值低于IMRT组(P＜0.05);两者的D50、D98和CI值差异无统计学意义(P＞0.05).对于OAR,两组计划的肺和心脏受照剂量差异均无统计学意义,但VMAT较IMRT能更好地保护脊髓(P＜0.05).机器跳数VMAT、IMRT分别为(668±121)、(612±101),有效治疗时间VMAT[ (4.4±0.3)min]比IMRT [(6.1±0.4) min]减少了38.6%(P＜0.05).结论 IMRT与VMAT均能满足胸上段食管癌的放疗剂量要求,VMAT可以达到或优于IMRT的靶区剂量分布,VMAT可降低脊髓受量,缩短治疗时间,提高治疗效率.“,”Objective To compare the dosimetric characteristics of volumetric-modulated arc therapy (VMAT) vs. static intensity-modulated radiation therapy (IMRT) for upper thoracic esophageal carcinoma. Methods Thirty patients with loco-regionally advanced upper thoracic esophageal cancer were enrolled. Two plans were generated using the same dose objectives for each patient: VMAT with a single arc, and IMRT with seven fields. The parameters evaluated included dose homogeneity (HI) and conformality (CI), dose to organs at risk (OARs), and delivery efficiency. Results All the VMAT and IMRT plans can satisfy the clinical dosimetry requirement. For PTV1, the D2 and HI values in VMAT were significantly lower than IMRT (P＜0.05). The CI of VMAT had statistically significant improvement compared with IMRT (P＜0.05). There was no significant difference in the D50, D98, and V110 values between VMAT and IMRT techniques (P＞0.05). For PTV2, the D2 and HI values in VMAT were significantly lower than IMRT (P＜0.05). There was no significant difference in the D50, D95, and CI values between VMAT and IMRT techniques (P＞0.05). For OARs, equivalent sparing of lung and heart were achieved with two plans. However, VMAT showed a superior sparing compared with IMRT for spinal cord (P＜0.05). The MU/fraction was as follows: (668±121) for VMAT, and (612±101) for IMRT. The delivery time of VMAT (4.4±0.3) min compared with IMRT (6.1±0.4) min was reduced by an average of 38.6% (P＜0.05). Conclusion Both IMRT and VMAT are appropriate for upper thoracic esophageal cancer radiotherapy. Compared with IMRT, VMAT showed similar or better dosimetric quality and superior spinal cord sparing. It has the advantages in shorter treatment time and higher treatment efficiency.