三种配准方式下腹部肿瘤IGRT摆位误差的比较

Comparative Study on Set-up Errors with Different Image Alignment for Abdominal Tumor Underwent Image Guided Radiation Therapy

目的探讨腹部肿瘤图像引导放射治疗(IGRT)治疗中不同图像配准方法对摆位误差的影响。方法医科达Synergy IGRT直线加速器分别治疗腹部肿瘤患者20例,每次治疗前均行锥形束CT(CBCT)扫描,重建获得的CBCT图像与原计划CT图像进行配准,分析X、Y、Z轴方向的平移误差及旋转误差,比较骨性配准、灰度值配准及手动配准间的差异。结果 20例腹部肿瘤患者治疗前共行282次CBCT扫描,手动配准、骨性配准、灰度值配准在X轴的平移误差分别为(-0.02±0.27)cm、(-0.04±0.28)cm、(-0.03±0.27)cm,在Y轴的平移误差分别为(0.08±0.46)cm、(0.11±0.48)cm、(0.09±0.48)cm,在Z轴的平移误差分别为(-0.01±0.28)cm、(-0.02±0.28)cm、(-0.02±0.28)cm;X轴的旋转误差分别为(0.57±1.78)°、(0.73±2.17)°、(0.67±1.98)°,在Y轴的旋转误差分别为(0.15±1.24)°、(0.12±1.51)°、(0.23±1.47)°,在Z轴的旋转误差分别为(0.05±0.92)°、(0.02±1.02)°、(0.18±1.04)°,其中骨性配准与灰度值配准结果差异无统计学意义,两者与手动配准的摆位误差结果差异有统计学意义。结论腹部肿瘤患者行IGRT时,需要根据病变具体部位选择配准方式,建议骨性配准后必要时结合手动微调,直到配准结果符合要求。

Objective To investigate the optimal alignment methods for the treatment of abdominal tumor in IGRT.Methods 20 abdominal tumor patients were treated with the Elekta Synergy IGRT system.KV-CBCT images received before every treatment fraction.The difference in bone alignment,grey value alignment and manual alignment was compared.Results Total of 282 sets of CBCT images were analyzed for 20 abdominal tumor.The mean±standard deviation in the X,Y and Z axis directions were（-0.02±0.27）cm,（-0.04±0.28）cm,（-0.03±0.27）cm;（0.08±0.46）cm,（0.11±0.48）cm,（0.09±0.48）cm;（-0.01±0.28）cm,（-0.02±0.28）cm,（-0.02±0.28）cm,respectively,in abdominal tumor with bone alignment,grey value alignment and manual alignment.The mean±standard deviation in the X,Y and Z rotation directions were（0.57±1.78）°,（0.73±2.17）°,（0.67±1.98）°;（0.15±1.24）°,（0.12±1.51）°,（0.23±1.47）°;（0.05±0.92）°,（0.02±1.02）° and（0.18±1.04）°,respectively,in abdominal tumor with bone alignment,grey value alignment and manual alignment.There was no significant difference between bone alignment and grey value alignment,but manual alignment was different from them.Conclusion There exists some extent of setup error in 3DCRT or IMRT of abdominal tumor patients.Which alignment can be chose based on the diseased region.It is suggested that manual adjustment after bone alignment is necessary.