Objective To investigate the clinical target volume (CTV)-planned target volume (PTV) setup margins during intensity-modulated radiotherapy (IMRT) for cervical cancer patients with different body mass index (BMI),aiming to provide reference for precise individual therapy.Methods Forty patients diagnosed with cervical cancer undergoing IMRT in Cancer Hospital of Fudan University between March and September 2017 were recruited and assigned into the BMI ≤ 18.4,18.5-23.9,24.0-27.9 and ≥ 28 kg/m2 groups according to the BMI classification criteria proposed by National Health and Family Planning Commission (NHFPC) of the People's Republic of China.Assisted with the bladder volume measurement device,9 cycles of kilo-voltage cone beam computed tomography (CBCT) images were subject to online registration and imaging analysis.CTV-PTV setup margins were calculated based on the formula of MPTV =2.5∑+0.7σamong four groups.Single factor variance analysis was performed.LSD test was utilized for two-group comparison.Results Among four groups,the CTV-PTV setup margins in the x,y and z directions were (6.87 mm,6.06 mm,8.49 mm),(3.13 mm,3.02 mm,3.14 mm),(4.70 mm,4.86 mm,5.31 mm) and (7.63 mm,8.28 mm,8.54 mm),respectively (P=0.038,0.048 and 0.004).Conclusions The setup errors in the BMI ≤ 18.4 and ≥28 kg/m2 groups are significantly larger compared with those in the remaining groups Consequently,CTV-PTV setup margins should be enlarged to certain extent for patients with BMI≤ 18.4 and ≥≥28 kg/m2.%目的 探讨不同BMI的宫颈癌患者放疗时CTV至PTV外扩边界,为实现精准的个体化分组治疗提供参考依据.方法 选取2017年3-9月复旦大学附属肿瘤医院接受IMRT宫颈癌患者40例,参考国家卫生和计划生育委员会提出的标准进行分组,BMI≤18.4 kg/m2为过轻组,18.5～23.9 kg/m2为正常组,24.0～ 27.9 kg/m2为过重组,≥28.0 kg/m2为肥胖组.在膀胱容积测量仪干预下分别采集9次治疗前的干伏级CBCT图像进行在线配准,并对配准结果进行分析.通过MPTV=2.5∑∨+0.7σ分析4组患者CTV至PTV外扩边界的差异.行单因素方差分析,两两比较行LSD检验.结果 过轻组,正常组,过重组及肥胖组患者CTV至PTV的外扩边界在左右、头脚、腹背方向上分别为6.87、6.06、8.49 mm,3.13、3.02、3.14 mm,4.70、4.86、5.31 mm及7.63、8.28、8.54 mm (P=0.038、0.048、0.004).结论 过轻患者和肥胖患者的摆位误差高于正常者和过重患者,故对于过轻患者和肥胖患者应适当增加CTV至PTV的外扩边界.
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