关于放疗位置验证方式的探讨

Discussion on verification methods of radiotherapy location

目的:探讨放疗全程进行位置验证的意义。方法:测量使用0.6 MU的剂量拍摄位置验证片时患者实际的吸收剂量,用计划系统计算患者整个疗程吸收剂量的改变。每次治疗前采用单次曝光成像技术拍摄正、侧位位置验证片,与首次位置验证片比对,记录左右、腹背和头脚方向的误差值,若超出误差阈值则纠正摆位后再进行治疗。前五次误差,首次、中间和末次误差以及全程位置验证的误差利用方差分析方法进行统计分析。结果:获取位置验证图像过程中患者平均吸收剂量为0.3 cGy,经过计划系统重新计算剂量分布,对靶区剂量无影响。三种位置验证方式中,全程位置验证的左右、腹背和头脚方向的误差均为最大,且差异有统计学意义(P<0.05)。三种位置验证方法中,腹背方向的误差均值最小,左右方向的误差均值最大,且差异有统计学意义(P<0.05)。结论:全程位置验证对于保证病人靶区位置的精确性是有意义的。

Objective:To explore the significance of location verification in the whole course of radiotherapy.Methods:Measuring the actual absorbed dose of patients in the process of getting location verification image with 0.6 MU,and calculating the changes of absorbed dose during the whole course of treatment with planning system.Before each treatment,the positive and lateral position validation images were acquired by single exposure imaging technology.Compared with the first position validation film,the left and right,abdomen and back,head and foot direction errors were recorded.If the error threshold was exceeded,the positioning was corrected before treatment.The error of first five times,first,intermediate and last times,and the whole course of location verification were analyzed by variance analysis method.Results:The average absorbed dose was 0.3 cGy during the acquisition of position verification images.The dose distribution was recalculated by the planning system and had no effect on the target volume.Among the three methods of location verification,the errors of left and right,abdomen and back,and head and foot directions were the largest,and the difference was statistically significant(P<0.05).Among the three location verification methods,the mean error of the front and back directions was the smallest,and the mean error of the left and right directions was the largest,and the difference was statistically significant(P<0.05).Conclusion:The whole course location verification of radiotherapy is significant to ensure the accuracy of target volume.