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目的探讨不同体质量指数食管癌患者放疗中的摆位误差。方法选取2012年6月至2016年2月间北京大学肿瘤医院暨北京市肿瘤防治研究所收治的88例行调强放疗的食管癌患者,根据体质量指数不同分为观察组(BMI≥25kg/m~2)28例与对照组(BMI<25kg/m~2)60例,两组患者均给予影像系统测量X轴、Y轴及Z轴的摆位误差,比较两组患者肿瘤控制概率和周围组织发生并发症概率,进行靶区剂量学分析。结果观察组患者X、Y和Z轴方向的摆位误差分别为(8.83±3.10)mm、(5.45±3.12)mm和(6.24±3.13)mm,均高于对照组患者的(2.41±1.93)mm、(2.11±1.33)mm和(1.98±1.56)mm,差异均有统计学意义(均P<0.05)。观察组患者的局部控制概率(TCP)、脊髓正常组织并发症概率(NTCP)与肺NTCP分别为(18.44±3.10)%、(4.87±1.09)%和(9.82±1.45)%,对照组患者分别为(18.56±4.19)%、(3.20±1.40)%和(8.08±1.66)%,观察组患者脊髓NTCP与肺NTCP均明显高于对照组,差异均有统计学意义(均P<0.05)。观察组患者计划靶区(PTV)-大体肿瘤体积(gtv)的最低剂量(Dmin)、平均剂量(Dmean)与95%体积的最低照射剂量(D95)比较,差异均无统计学意义(均P<0.05)。结论体质量指数≥25kg/m~2的食管癌患者,在放疗中会增加各个方向的摆位误差,加大脊髓与肺部正常组织并发症发生概率。
Objective To investigate the setting error of radiotherapy for different body mass index patients with esophageal cancer. Methods From June 2012 to February 2016, 88 patients with esophageal cancer treated with intensity modulated radiotherapy from Peking University Cancer Hospital and Beijing Cancer Institute were selected and divided into observation group (BMI≥25kg / m ~ 2), 28 cases and control group (BMI <25kg / m ~ 2) 60 cases, both groups were given imaging system to measure the X axis, Y axis and Z axis positioning errors, comparing the two groups of patients with tumor control probability and Surrounding tissue complication probability, the target area dosimetric analysis. Results The setup errors in the X, Y and Z axis directions were (8.83 ± 3.10) mm, (5.45 ± 3.12) mm and (6.24 ± 3.13) mm in the observation group, which were higher than those in the control group (2.41 ± 1.93) mm, (2.11 ± 1.33) mm and (1.98 ± 1.56) mm, respectively, with significant difference (all P <0.05). The TCP, NTCP and NTCP in the observation group were (18.44 ± 3.10)%, (4.87 ± 1.09)% and (9.82 ± 1.45)%, respectively, while those in the control group were (18.56 ± 4.19)%, (3.20 ± 1.40)% and (8.08 ± 1.66)%, respectively. NTCP and NTCP in the spinal cord of the observation group were significantly higher than those of the control group (all P <0.05). The lowest target dose (PTV) -to gross tumor volume (gt) and the lowest mean dose (Dmean) of the observation group were not significantly different from the 95% minimum dose (D95) <0.05). Conclusion Patients with esophageal cancer with body mass index ≥25kg / m ~ 2 will increase the error of positioning in all directions during radiotherapy, and increase the probability of complications of spinal cord and lung tissue.