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目的:探究对鼻咽癌患者调强放射治疗（IMRT）中摆位误差对靶体积和关键结构的影响。方法:选择2018年1月至2019年3月浙江省肿瘤医院就诊且接受放疗的60例鼻咽癌患者，均接受同步整合加量IMRT；设定肿瘤总体积、临床靶体积、低风险淋巴结区域分别为70.0、59.4及54.0 Gy，总计33次分割；前、后、上、下、左、右同中心移动3、5及10 mm用以模拟摆位误差；评估平均剂量、最大剂量、计划靶区体积（PTV）接受量>110%与50%腮腺的剂量；分析最大剂量及2cc脊髓接受剂量。结果:与无位移相比，肿瘤总体积（GTV-70.0 Gy）在3 mm等中心位移的平均剂量最大百分比变化偏小2.2%，5 mm和10 mm等中心位移平均剂量的最大百分比变化分别为6.4%和16.0%；不同位移的临床靶体积（CTV）与计划靶体积（PTV）剂量体积分析显示，CTV-54.0 Gy的体积为（112.06 ± 55.92）cc（50.6~243.8 cc），相对于无位移，接受处方剂量（V54%）3、5和10 mm等中心位移最大百分比变化分比为1.5%、6.8%和23.8%。沿后侧及外侧摆位误差3 mm可显著影响脊髓的剂量；摆位误差沿外侧与前侧方向可显著影响两侧腮腺的剂量，朝患者右侧位移10 mm产生的最大剂量为（46.28 ± 5.10）Gy，同样条件下左侧位移产生的最大剂量为（46.38 ± 5.35）Gy。结论:鼻咽癌调强放疗中对于摆位误差应常规定时确认同中心位置，以实现较为理想的靶区体积剂量，改善治疗效果。“,”Objective:To investigate the effect of placement error on target volume and critical structure in intensity modulated radiation therapy (IMRT) in patients with nasopharyngeal carcinoma.Methods:The study period was from January 2018n to March 2019.The 60 patients with nasopharyngeal carcinoma who were treated in Zhejiang Cancer Hospital for this period and received radiation therapy were treated with simultaneous integration and intensity-modulated radiation therapy.The total tumor volume and clinical setting were set. The target volume and low-risk lymph node area were 70.0, 59.4 and 54.0 Gy respectively, with a total of 33 divisions; 3, 5 and 10 mm were moved around the top, bottom, left and right to simulate the placement error; the average dose, the maximum dose, the planned target volume and >110% and 50% parotid gland dose was evaluated; the maximum dose and 2 cc spinal cord tolerance dose were analyzed.Results:Compared with no displacement, the maximum percentage change in the average dose of the total tumor volume (GTV-70 Gy) at the center displacement of 3 mm was smaller (2.2%), and the maximum percentage changes of the average dose at the center displacement of 5mm and 10mm were 6.4% and 16.0% respectively.; Analysis of clinical target volume (CTV) and planned target volume (PTV) dose volume analysis of different displacements showed that the average volume of CTV-54 Gy was (112.06 ± 55.92) cc (range 50.6-243.8 cc), compared to V54 (%) The maximum percentage changes of center displacements of 3, 5 and 10 mm were 1.5%, 6.8% and 23.8%. The positioning error of 3mm along the posterior and lateral sides can significantly affected the dose of the spinal cord; the positioning error along the lateral and anterior directions could significantly affect the dose of the parotid glands on both sides. The maximum average dose produced by the left displacement under the same conditions was (46.38 ± 5.35) Gy.Conclusions:In the intensity-modulated radiotherapy for nasopharyngeal carcinoma, the position error should be confirmed regularly at the same time to achieve a better target volume dose and improve the treatment effect.