摘要目的 研究螺旋断层放疗(TomoTherapy治疗中不同部位肿瘤的摆位误差分布规律.方法 回顾性分析接受TomoTherapy治疗的151例患者的摆位,其中头颈部53例,胸部45例,腹部20例,盆腔33例.获得患者计划CT图像,并在每次治疗前行兆伏级CT(MVCT)扫描获得MVCT图像,两者刚性配准后计算出摆位误差,分别对+x(左)、-x(右)、+y(进)、-y(出)、+z(腹)和-z(背)6个方向的摆位误差进行分析.结果 151例患者共进行MVCT扫描3 281次,6个方向的摆位误差在头颈部分别为(1.61±1.21)、(1.76±2.11)、(2.26±1.74)、(1.83±1.47)、(3.24±1.76)和(1.75±1.61)mm;在胸部分别为(2.43±1.88)、(2.55±1.92)、(3.06±2.64)、(3.90±2.91)、(6.71±3.46)和(2.64±2.77) mm;在腹部分别为(3.67±3.06)、(2.37±1.77)、(3.18±1.96)、(3.98±3.01)、(6.74±3.25)和(1.92±2.00) mm;在盆腔分别为(2.92±2.13)、(2.17±1.68)、(3.50±2.61)、(3.72±2.66)、(7.18±3.43)和(1.92±1.61)mm.各部位肿瘤+z和-z摆位误差间的差异均具有统计学意义(t=-4.119、-5.033、-3.763、-5.057,P＜0.05);胸部肿瘤用热塑性体膜定位的患者其在+z方向的摆位误差要小于采用真空负压袋定位者(t=-2.357,P＜0.05).结论 TomoTherapy治疗时,头颈部肿瘤摆位精度优于其他部位;胸部肿瘤用热塑性体膜固定可以进一步减少摆位误差;而不同部位肿瘤在腹背方向摆位误差的异质性不容忽视.

abstractsObjective To investigate the distribution rules of setup errors in different locations for tomotherapy.Methods 151 patients induding 53 head and neck tumors,45 thoracic tumors,20 abdominal tumors,and 33 pelvic tumors,who accepted tomotherapy were retrospectively analyzed in this study.The planning CT images of patients were obtained in simulation,and all patients underwent megavoltage CT (MVCT) scan before radiotherapy.And the setup errors were calculated by rigid registering MVCT images to planning CT images,and setup errors on + x(left),-x(right),+ y(in),-y(out),+z(ventral),-z (dorsal)axes were analyzed respectively.Results A total of 3 281 MVCT scans were performed on 151 patients,The setup errors on +x (left),-x(right),+y(in),-y(out),+z (ventral),-z (dorsal)axes were (1.61 ± 1.21),(1.76 ±2.11),(2.26 ± 1.74),(1.83 ± 1.47),(3.24±1.76) and (1.75 ± 1.61)mm for head and neck tumors;(2.43 ±1.88),(2.55 ± 1.92),(3.06 ±2.64),(3.90 ±2.91),(6.71 ±3.46) and (2.64 ±2.77)mm for thoracic tumors;(3.67±3.06),(2.37±1.77),(3.18±1.96),(3.98±3.01),(6.74±3.25) and (1.92±2.00) mm for abdominal tumors;(2.92 ±2.13),(2.17±1.68),(3.50±2.61),(3.72±2.66),(7.18± 3.43) and (1.92 ± 1.61)mm for pelvic tumors,respectively.The setup errors were different between +z and-z with statistically significant in all tumors (t =-4.119、-5.033、-3.763、-5.057,P ＜ 0.05).The setup errors on + z direction of patients immobilized with thermoplastic mask were smaller than those immobilized with vacuum cushions for thoracic tumors (t =-2.357,P ＜ 0.05).Conclusions The setup errors of head and neck tumors are less than other parts tumor in tomotherapy.The patients immobilized with thermoplastic mask can reduce the setup errors for thoracic tumors.The heterogeneity of setup errors on ventral-dorsal directions for the all parts of tumors should not be ignored.