基于NCC/T-RT 001-2019质控指南进行医用加速器质控的研究  

Research on Quality Control of Medical Accelerator Based on the NCC/T-RT 001-2019 Guidelines

作　　者：顾香莲 顾煜恺 龚卿 GU Xianglian;GU Yukai;GONG Qing(Department of Radiotherapy,Longhua Hospital,Shanghai University of Traditional Chinese Medicine,Shanghai 200032,China)

机构地区：[1]上海中医药大学附属龙华医院放疗科,上海200032

出　　处：《中国医疗设备》2021年第7期68-72,共5页China Medical Devices

摘　　要：目的探索NCC/T-RT 001-2019《医用电子直线加速器质量控制指南》中关于光距尺、多叶准直器(Multi-Leaf Collimator,MLC)动态日志文件分析和机架-光栏-治疗床同心度测试方法的改进方案以期获得更可靠的结果。方法使用千分计在1/100 mm精度上测量床面因固体水模引起的弯曲下垂;对Step&Shoot和Sliding Windows调强射野的MLC日志文件Dynalogs使用能剔除束流悬停记录的Argus软件和无数据筛选选项的Dynalogs Viewer软件分别统计叶片位置偏离均方根值,并对同时采集的射野剂量图像进行通过率分析;使用电子射野影像系统(Electronic Portal Imaging Device,EPID)替代胶片进行Winston-Lutz测试,比较由光栏形成的方野与SRS照射孔形成的圆野对结果的影响。结果20 cm固体水体模额外带进治疗床面高度变化1.42 mm,占该项允许误差的70%;Argus与Dynalogs Viewer在Step&Shoot的调强射野中能得到明显不同的统计结果,但两种软件给出的结果与EPID剂量影像的g分析结果之间相关性分析的P值分别为0.66和0.67,无统计学意义;在加速器机架-光栏-治疗床的旋转同心度的Winston-Lutz测试中,依据用光栏页与用SRS照射孔的影像得到的同心度的最大/平均误差分别为1.29/0.93 mm和0.62/0.37 mm,结果相差一倍多,并且前者达到了用于SRS/SBRT加速器误差的临界值。结论指南规定的质控测试方法可能会引入新的不确定性,本文提出了一些与测试允许误差要求相分辨率匹配的检测方法,也建议质控指南再版时能否在规定精度指标指导原则的同时将具体的测量留给医院的质控小组根据自身设备条件制定因地制宜的方法。Objective To explore the improvement of NCC/T-RT 001-2019 Guidelines of Quality Control of Medical Linear Accelerators on the analysis of dynamic logs file of light distance scale and multi-leaf collimator(MLC),and the test method of gantry-collimator-couch concentricity,in order to obtain more reliable results.Methods Measuring the couch sag with micrometer for 1/100 mm precision.Using software named Argus(with the beam-hold records filtering function)and Dynalogs Viewer(no data filtering option)to export the root mean square value(RMS)of MLC leaf error from the MLC log file for Step&Shoot and Sliding Windows fields and compare them with the evaluation of dose image.The Winston Lutz test was performed by using electronic portal imaging device(EPID)instead of film to acquire the Winston-Lutz images.Then,the effects of collimator square field and SRS cone images on the results were compared.Results 1.42 mm couch sag was confirmed due to the 20cm solid water phantom which was about 70%of the tolerance.Different RMS of leaf error were conducted from Argus and Dynalogs Viewer with Step&Shoot fields.When comparing them to the g evaluation of dose image,the P values were 0.66 and 0.67 which mean no correlation between the g evaluation and RMS statistics from both software.In Winston-Lutz testing,the maximum/mean deviations were 1.29/0.93 mm and 0.62/0.37 mm respectively from collimator square field and SRS cone circular field,the latter was about the half of the former which was at the tolerance limit of linear accelerators for SRS/SBRT purpose.Conclusion The extra uncertainties may be introduced by the testing defined by the guidelines.This paper introduces some methods for taking account of the issues for matching the tolerances.It is also suggested in this paper that the revision of the national guidelines of quality control might focus on the testing principles and setting of the tolerances,but can we leave some flexibilities to local quality control team to decide their own testing procedures based on their equipm

关 键 词：质量控制 多叶准直器 等中心 源皮距 

分 类 号：R197.39[医药卫生—卫生事业管理]