【作者】 徐鹭英； 潘建基； 王笑良； 李奇欣； 柏朋刚； 陈传本； 马礼钦；

【Author】 XU Lu-ying,PAN Jian-ji,WANG Xiao-liang,LI Qi-xin,BAI Peng-gang,CHEN Chuan-ben,Ma Liqin The Teaching Hospital of Fujian Medical University,Fujian Provincial Cancer Hospital, Fuzhou,350004,China

【机构】 福建医科大学教学医院 福建省肿瘤医院；

【摘要】 目的:通过CBCT影像图与计划CT图像匹配获得IMRT治疗中6个自由度的摆位误差,分析摆位误差对肿瘤计划靶区(GTV-P)、脑干及腮腺受照剂量的影响,探讨头颈部肿瘤IMRT放疗过程中摆位误差在线校正的必要性。材料及方法:30例头颈部肿瘤患者每周一次在放疗前行治疗机下CBCT扫描,扫描后的CT影像与计划CT的影像比较,分别获得Z轴、X轴和Y轴方向的平移摆位误差,以及以X、Y、Z轴旋转的旋转误差。根据每次摆位误差的数据重新做计划得到GTV-P、脑干和腮腺等的剂量或体积(实验组),与30例原计划相应靶区及危及器官的剂量或体积(对照组)比较,分析其剂量或体积的变化。结果:30例患者6个自由度的摆位误差:Z轴1.31±1.07mm,X轴1.06±0.95mm,Y轴0.95±0.77mm;X、Y、Z轴旋误差为:1.04±0.79度,1.06±0.89度,0.81±0.61度。实验组GTV-PD95、GTV-P Dmin均明显小于对照组,并有显著意义(P<0.05);实验组脑干V45及D1明显大于对照组(P<0.05)。两组GTV-P的Dmax和Dmean、双侧腮腺V25无显著差异(P>0.05)。结论:头颈部肿瘤平移误差在各个方向不一致,以Z轴方向最大,而旋转误差均在2度以。6个自由度的摆位误差导致GTV-P(D95)剂量明显不足,明显降低了GTV-P内的剂量均匀性;脑干受照射的剂量及体积均明显增加。因此,头颈部肿瘤放疗在线纠正是必要的。更多还原

【Abstract】 Objective To measure the six-dimension(6-D ) couchtop setup errors of patients with head and neck cancer(H&N cancer ) during the intensity-modulated radiation therapy(IMRT) treatment and analyze the impact of 6-D couchtop setup errors on dose distribution;then to further investigate the necessity of adjustment online for H&N cancer during IMRT treatment.Materials and methods Thirty H&N cancer patients treated with IMRT were recruited between October 2009 and February 2010.Weekly Cone--Beam CT scans of thirty H&N cancer patients were acquired during IMRT treatment.The scanned CBCT images and the original treatment planning CT images were matched by the bony structure and worked out the translational errors of the X,Y,Z axis,as well as rotational errors of X,Y,Z axis.The replanning were done based on the data of each setup error.The dose volume of GTV-P and OAR were calculated in replanning,and than compared with the dose volume of the original plan.Results The mean value of X,Y,Z axis translational setup errors were 1.06±0.95mm,0.95±0.77mm and 1.31±1.07mm,respectively.The rotational error of X,Y,Z axis were 1.04±0.791°,06±0.89°and 0.81±0.61°,respectively.The GTV-P D95 of the replanning group were significantly less than that of the original plan group(P <0.05);The minimum value of the GTV-P in the replanning group were significantly less than that of the original plan group(P <0.05);The dose distributions of brainstems(V45 and D1) in the replanning group were significantly higher than those of the original plan group(P <0.05);There were no significant difference between replanning group and original plan group for the GTV-P maximum dose and mean dose and the V25 of the bilateral parotid glands(P> 0.05).Conclusions The translational errors of H&N cancer were inconsistent in all directions.The direction of Z-axis(anterior-posterior) was the largest and the rotational errors were all less than 2°,therefore,in the clinic it was recommended that the PTV should be expanded different margin in different directions.The setup errors led to the dose of GTV-P (D95) obviously insufficient and the dose of GTV-P nonuniformity,significantly increased V45,Dl of the brainstem.So,adjustment online is necessary for H&N cancer during IMRT treatment.更多还原