Objective To evaluate the value of volumetric modulated arc therapy ( VMAT) in postopera-tive radiotherapy for cervical cancer .Methods Eighty four cases of cervical cancer patients were retrospectively analyzed after surgery .Thirty-nine patients received volumetric modulated arc therapy , while the other forty -five patients received three -dimensional conformal radiation therapy (3DCRT).The images were collected both before and after treatment.We recorded the setup errors including x (lift-right),y(ventral-dorsal),and z(an-terior-posterior)axes in thirty -nine patients with cone beam CT (CBCT).These images were compared with correponding planning images to calculate the position errors .We also analyzed the radiation dosimetry parameters and adverse reactions .Results The setup errors before and after radiation therapy in x ,y,and z axes were (1.07 ±0.91)cm,(0.76 ±1.07)cm,(0.74 ±0.81)cm and(0.11 ±0.04)cm,(0.11 ±0.09)cm,(0.08 ±0.20) cm,respectively.These data showed that the application of CBCT reduced the setup errors of treatment significant -ly.We analyzed the illuminated volume of bladder and rectum with dose volume histogram (DVH),and found there was no difference between VMAT and 3DCRT groups when 20 Gy irradiation dose was adopted .When the ir-radiation dose increased to 30 Gy and 40 Gy, the corresponding illuminated volume of bladder and rectum in VMAT group were 69.45 ±1.13,41.78 ±2.8 and 75.66 ±3.34,30.12 ±9.59,respctively.In the 3DCRT group,the corresponding illuminated volume of bladder and rectum were 93.37 ±6.59,88.32 ±12.13 and 95.26 ±8.95,90.32 ±6.98,respectively.VMAT can obviously decrease the illuminated volume of bladder and rectum when compared to 3DCRT.Conclusion VMAT can not only decrease the setup errors to improve the accuracy of radiotherapy ,but also reduce the reaction of normal tissues effectively in the cervical cancer patients who accepted postoperative radiotherapy .Therefore,the VMAT technology can improve both patients′treatment compliance and their quality of life .%目的：探讨容积旋转调强技术在宫颈癌术后放疗中的应用价值。方法哈尔滨医科大学附属肿瘤医院收治的宫颈癌患者84例，其中行容积旋转调强放疗（ Volumetric modulated arc therapy ， VMAT）39例，行3DCRT 45例。对行VMAT 39例患者采集摆位后、纠正后CBCT图像。获得左右（ x）、头脚（ y），前后（ z）方向结果，并根据误差值调整治疗床的位置，对两组患者的靶区的剂量学参数及毒副反应进行分析。结果患者治疗前CBCT左右（x1）、头脚（y1），前后（z1）三个方向检测结果分别为（1．07±0．91）cm、（0．76±1．07）cm、（0．74±0．81）cm；治疗后CBCT左右（x2）、头脚（y2），前后（z2）三个方向检测结果分别为（0．11±0．04）cm、（0．11±0．09）cm、（0．08±0．20）cm。通过数据表明患者治疗后x、y、z三个方向误差均小于治疗前。通过剂量体积直方图（ DVH）对两种照射技术中膀胱及直肠受照剂量体积进行分析，显示当接受20 Gy剂量照射时，两种照射方式的膀胱和直肠照射体积无明显差异。当接受30 Gy、40 Gy照射时，VMAT组膀胱受照体积为69．45±1．13和41．78±2．80；3DCRT组膀胱受照体积为93．37±6．59和88．32±12．13。 VMAT组直肠受照体积为75．66±3．34和30．12±9．59；3DCRT组直肠受照体积为95．26±8．95和90．32±6．98。两组接受30 Gy、40 Gy照射时，膀胱及直肠体积差异具有统计学意义。结论采用容积旋转调强技术不仅可以减少宫颈癌术后放疗过程中的摆位误差，提高肿瘤放疗的精确度，降低正常组织的剂量，而且有效降低正常组织的反应，提高患者的依从性，改善患者的生存质量。
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