Objective:To analyze and compare the differences in dosimetric parameters between two radiotherapy techniques[dynamic intensity modulated radiotherapy(dIMRT)and volumetric modulated arc radiotherapy(VMAT)]for cervical or upper tho-racic esophageal cancer patients,as well as the dose robustness of dIMRT and VMAT under the introduction of 3 mm positioning error.Methods:Selected 22 patients with cervical or upper thoracic esophageal cancer who undergo radical radiotherapy to design a radiother-apy plan.Design dIMRT and VMAT radiotherapy plans simultaneously for each patient,and compare the dose differences between the two radiotherapy plans in the lungs,heart,spinal cord,and other areas.Each technology plan involved translating the treatment center in 6 directions,including the X-axis(left and right),Y-axis(front and back),and Z-axis(head and feet),with a simulated positioning error of 3 mm.The dose distribution of the target area and endangered organs was recalculated,and the changes in the dose distribution of the target area and endangered organs compared to the original plan are observed.Results:Both radiotherapy techniques were able to achieve the prescribed dose in the target area,with high conformability and uniform dose distribution within the target area.Both lungs:For V5,V10,V15,V20,V30,and Dmean,dIMRT was slightly higher than VMAT,and the difference was statistically significant(P＜0.05).Heart:For V20,V30,V40,and Dmean,VMAT was slightly higher than dIMRT,and the difference was statistically signifi-cant(P＜0.05).Under the introduction of 3 mm positioning error,the prescription dose in the target area was not reduced,and the ra-diation dose to organs at risk was also within the dose limit range.The difference in radiation dose and volume between dIMRT and VMAT target areas and surrounding organs at risk was not significant,and the robustness of the two was consistent.Conclusion:When endangering organs,VMAT has a higher radiation dose to the heart than dIMRT,and dIMRT has a higher radiation dose to the lungs,but both are within the dose limit range.DIMRT has fewer machine hops and shorter treatment time for VMAT.When introducing a 3 mm positioning error in the X,Y,and Z axes,left and right,front and back,and head and foot directions,there is little change in the dosime-tric parameters of dIMRT and VMAT,and their robustness is consistent.