利用缩野定位CT扫描测量三维适形调强治疗中的摆位误差  

Set-up errors in three-dimensional conformal/intensity-modulated radiation therapy measured with repeat CT scans for reducing taget volume

作　　者：李云海[1] 沈琰琦[1] 李永春[1] 王月琴[1] 夏怡[1] 陈剑[1] 肖锋[1] 赵森[2,3] 

机构地区：[1]复旦大学附属肿瘤医院闵行分院放疗科,上海200240 [2]复旦大学附属肿瘤医院放疗科,上海200032 [3]复旦大学上海医学院肿瘤学系,上海200032

出　　处：《复旦学报（医学版）》2010年第6期652-656,共5页Fudan University Journal of Medical Sciences

基　　金：上海市闵行区科学技术委员会项目(0612)

摘　　要：目的利用缩野定位CT扫描研究在三维适形调强治疗中热塑成型面罩/体膜固定的摆位不确定程度,并探讨不同部位的计划靶区（planning target volume,PTV）外放间距。方法对77例放疗患者进行前后两次CT扫描,第二次CT扫描为靶区缩野定位扫描,仍采用原有固定装置,保证摆位及固定方法、扫描参数及扫描范围与首次CT扫描完全相同。选取相同的解剖骨性标志点为原点建立坐标轴,测量左、中、右3个标志点在坐标轴X、Y、Z方向上的数值,前后两次数值差的绝对值即为标志点在治疗过程中的摆位误差。结果左、中、右3个标志在不同部位肿瘤患者两次CT扫描之间的差距无一致性,头部及头颈肩部固定的摆位误差较小,胸部及腹盆部的固定摆位误差较大,胸部及腹盆部的误差均值均大于3 mm。头部和头颈部肿瘤PTV外放间距为3~8 mm,而胸部和腹盆部肿瘤PTV外放间距则为6~16 mm。结论即使两次激光标志点吻合相当精确,相对于骨性解剖标志点仍产生偏移。放疗必须要求足够的质控措施来保证治疗的精确,尤其是胸部及腹盆部肿瘤的调强放疗,图像引导放疗（image-guided radiation therapy,IGRT）可能是解决手段之一。Objective To study the set-up errors of thermoplastic mask used for the immobilization of patients treated by three-dimensional conformal/intensity-modulated radiation therapy measured with repeat CT scans in order to reduce target volume.Methods Seventy-seven patients underwent CT scans before and during treatment,and the second CT scan used to reduce target volume was as same as the first scan in the position of patients,immobilization,scanning parameters and scopes.The same anatomical bony landmarks were selected to establish the origin axis,and were measured the shift of left,middle,right marks in X,Y and Z direction,respectively.During the treatment,the absolute values of the shift of three marks was set-up errors.Results Patients in the study had no consistency of the shift of left,middle and right marks in CT scans.Set-up errors in head,head and neck and shoulder positions were small,but they were large in thoraci,abdominal and pelvic positions,and both were larger than 3 mm.The margins from clinical target volume（CTV） to planning target volume（PTV） was 3-8 mm in head,head and neck and shoulder positions and they were 6-16 mm in thoraci,abdominal and pelvic positions.Conclusions Even if the laser landmarks matched very precise,an offset was still emerged comparing to the bony anatomy.Radiation therapy must be under sufficient quality control measures to ensure treatment accuracy,while it must consider carefully to delive the intensity-modulated radiation therapy in the thoraci,abdominal and pelvic tumor.Image-guided radiation therapy（IGRT） may be one of the solutions.

关 键 词：断层摄影术X线 计算机 摆位不确定度 热塑成型面罩/体膜 放疗 

分 类 号：R817.5[医药卫生—影像医学与核医学] R730.55[医药卫生—放射医学]