ExacTrac图像引导系统在鼻咽癌IMRT中的应用

目的探讨ExacTrac图像引导系统在鼻咽癌调强放射治疗(IMRT)摆位误差全程管控中的应用价值。方法收集2018年3月至2018年8月接受IMRT的30例鼻咽癌患者,采用ExacTrac图像引导系统全程实施图像引导放射治疗(IGRT),分析左右、头脚、腹背3个平移方向及绕此3个方向旋转角度上的6D误差。结果ExacTrac图像引导系统校正前左右、头脚、腹背3个平移方向的误差值分别为(0.11±1.52)mm、(1.45±2.40)mm和(0.67±1.65)mm,绕此3个方向的旋转误差值分别为(-0.16±1.12)°、(0.32±1.59)°、(-0.38±1.12)°。校正后,左右、头脚、腹背3个平移方向的误差值分别为(-0.04±0.46)mm、(0±0.42)mm和(0.03±0.54)mm,绕此3个方向的旋转误差值分别为(-0.03±0.25)°、(0.01±0.23)°和(0.01±0.28)°。校正后在左右、头脚、腹背3个平移方向及绕此3个方向的旋转角度上,≤1 mm或1°的误差概率分别为99%、100%、99%、100%、100%和100%。2 mm或2°的误差概率在左右平移方向为1%,腹背平移方向为1%,其余方向为0。≥3 mm或3°的误差概率均为0。ExacTrac图像引导系统校正前后6D方向摆位误差的差异有统计学意义(P<0.05)。结论鼻咽癌患者在实施每分次IMRT的过程中行IGRT非常必要,应用ExacTrac图像引导系统可以明显校正摆位误差,提高放疗精准性。

Application of ExacTrac image guidance system in nasopharyngeal carcinoma underwent IMRT

Objective To investigate the whole process control of ExacTrac image guidance system on the positioning error of intensity modulated radiation therapy(IMRT)for nasopharyngeal carcinoma and explore its clinical application value.Methods Thirty patients with nasopharyngeal carcinoma who underwent IMRT from March 2018 to August 2018 were enrolled,and ExacTrac image guidance system was used to perform image-guided radiation therapy(IGRT)throughout the radiotherapy.The 6D errors of horizontal direction and the rotation angle around the three directions were analyzed.Results The set-up errors of left and right,head and feet,as well as abdomen and back at horizontal direction were(0.11±1.52)mm,(1.45±2.40)mm and(0.67±1.65)mm,and those of rotation direction were(-0.16±1.12)°,(0.32±1.59)°and(-0.38±1.12)°.After correction,those data were(-0.04±0.46)mm,(0±0.42)mm,(0.03±0.54)mm,(-0.03±0.25)°,(0.01±0.23)°and(0.01±0.28)°.The error probability of≤1 mm or 1°in the three horizontal directions of left and right,head and feet,abdomen and back,and rotation around the three directions were 99%,100%,99%,100%,100%and 100%,respectively.The error probability of 2 mm or 2°were as follows:the left-right horizontal direction was 1%,the abdomen-back horizontal direction was 1%,and the remaining directions were 0.The error probability of≥3 mm or 3°was 0.The 6D directional error test values before and after ExacTrac image guidance correction were statistically significant(P<0.05).Conclusion It is very necessary to perform IGRT in patients with nasopharyngeal carcinoma during the implementation of each minute of IMRT.ExacTrac image guidance system can significantly correct the placement error and improve the accuracy of radiotherapy.