Abstract: Objective To compare different beam arrangements in 7-field intensity-modulated radiation therapy（IMRT） to treat nasopharyngeal carcinoma by analyzing doses delivered to target tissue and adjacent normal tissue. Methods A total of 12 patients with nasopharyngeal carcinoma who had been prescribed the same total IMRT dose were treated with one of the following three IMRT plans：average plan，with a beam angle interval of 51°；anterior plan，with a beam angle interval of 42°；and a non-coplanar plan，involving 5 coplanar fields with a beam angle interval of 72°，as well as 2 non-coplanar fields with a couch angle of 90° and gantry angles of 30° and 330°. All plans were optimized using the same constraints to ensure comparability of the results.The following out-comes were measured：dose distribution to the planned target volume（PTV） and to organs at risk，dose volume histogram，PTV confor-mity index，mean dose（Dmean），minimum dose，and maximum dose（Dmax）. Results The three IMRT plans provided similar dose distributions to the PTV.The anterior plan provided a slightly higher Dmax-1%（D₁） to the spinal cord and brain stem than did the other plans，but this difference was very small and within the range of tolerated doses.The average plan provided a temporal lobe dose D₃₃ that was 9.28% smaller than that of the anterior plan and 12.38% smaller than that of the non-coplanar plan.The non-coplanar plan provided a lower D₅₀ to the parotid gland and temporomandibular joint than did the other plans，and the non-coplanar plan provided a temporomandibular joint dose D50 that was 30.47% smaller than that of the average plan and 33.29% smaller than that of the anterior plan.The non-coplanar plan provided an oral mucosa Dmean that was 10.49% higher than that of the average plan and 10.85% higher than that of the anterior plan. Conclusion Satisfactory dose coverage in the nasopharyngeal carcinoma target volume was achieved using 7-field IMRT.By designing individualized IMRT plans based on the location and volume of the target area， and by optimizing the type of beam arrangement，the dose distribution can be improved and the risk of affecting normal tissue signifi-cantly reduced.

Key words:  Nasopharyngeal neoplasms, Beam angle, Intensity-modulated radiation therapy, Bose distribution