螺旋断层放射治疗胰腺癌摆位误差分析

目的分析在兆伏级电子计算机断层扫描(MVCT)图像引导下采用螺旋断层调强放疗技术治疗胰腺癌患者的摆位误差,并计算计划靶区(PTV)的边界(margin)外放。方法行MVCT图像扫描,将扫描获取的MVCT图像与计划CT图像进行配准,记录左右(X)、头脚(Y)、腹背(Z)轴方向和横断面旋转(roll)方向的误差值,并对误差值进行分析计算。结果共行592次MVCT扫描。X、Y、Z和roll方向摆位误差值分别为(-0.5±2.8)mm、(-1.1±6.4)mm、(6.0±4.4)mm和(-0.2±0.7)°。X、Y和Z 3个方向上的平均误差小于5 mm,所占比例分别为97.13%(575/592)、88.01%(521/592)和37.84%(224/592),roll方向旋转误差小于1°,所占比例为93.92%(556/592)。根据公式得出在X、Y和Z 3个方向PTV的边界外放间距值分别为5.2、9.9和7.5 mm。结论对MVCT图像引导下行螺旋断层放射治疗胰腺癌患者的摆位误差数据分析,为提高放射治疗精度及疗效,推荐胰腺癌放疗在X、Y和Z三维方向上CTV到PTV的margin外放值分别为5、10和8 mm。

Margins of planning target volume in pancreatic cancer with tomotherapy

Objective Analysis of the pendulum error of pancreatic cancer patients by spiral tomography technique under the guidance of megavolt CT(megavoltage computed tomography,MVCT)image,and calculation of planned target volume,PTV of the margin.Methods The MVCT image scan matched with the planned CT image,the error values of the left and right(X),head and feet(Y),abdominal back(Z)axis direction and cross-section rotation(roll)direction were recorded,and the error values were analyzed and calculated.Results A total of 592 MVCT scans were conducted.The X,Y,Z and roll direction swing error values were(-0.5±2.8)mm,(-1.1±6.4)mm,(6.0±4.4)mm,and(-0.2±0.7)respectively.The average error in the three directions of X,Y and Z was less than 5 mm,with 97.13%(575/592),88.01%(521/592)and 37.84%(224/592),and roll direction rotation error of less than 1 degree,with 93.92%(556/592).According to the formula,the extra-boundary spacing values of The PTV in X,Y and Z 3 directions were 5.16,9.9 and 7.53 mm respectively.Conclusions In order to improve the accuracy and efficacy of tomotherapy,The margin emission values of CTV to PTV in X,Y and Z three-dimensional directions are recommended as 5,10 and 8 mm,respectively.