国产医用直线加速器开展立体定向放射治疗的可行性研究

Feasibility study of applying domestic medical linear accelerators in stereotactic radiotherapy

目的:从剂量输出、机械性能和辐射性能方面比较两种进口医用电子直线加速器和3种国产医用电子直线加速器的各项参数指标,对比分析国产医用直线加速器的技术和性能是否达到开展立体定向放射治疗的基本标准。方法:选取两种开展过立体定向放射治疗的进口医用电子直线加速器和3种装机量较大的国产医用电子直线加速器。利用电离室和静电计在水模体上测量加速器的剂量输出性能;利用坐标纸、前指针、刻度尺等工具测量加速器机械精度;通过PIPSpro5.3.1和doselab图形分析软件测量加速器辐射性能和到位精度,从而分析固体水和EBT免冲洗胶片记录辐射野。结果:以AAPM TG-142和中华人民共和国医药行业标准YY0832.2-2015为参考,建立一套完整的针对国产电子医用直线加速器的评价标准。检测发现国产加速器输出剂量精度、重复性、线性较高,旋转机架、准直器和治疗床辐射野等中心精度大部分小于1 mm,铅门和多叶准直器平均到位精度小于0.5 mm,两种国产加速器端对端偏差结果小于5%,说明国产加速器基本性能较好。结论:部分国产加速器从剂量输出和治疗精度方面已达到开展立体定向放射治疗的基本要求,但开展立体定向治疗需要相关放疗单位投入更多的人力和相应设备做好加速器的质量保证和质量控制工作。

Objective To evaluate the dose output,mechanical and radiation performances of 2 imported medical linear accelerators and 3 domestic medical linear accelerators for analyzing the performance of domestic medical linear accelerators and assessing whether it is suitable for stereotactic radiotherapy.Methods Two imported medical linear accelerators which stereotactic radiotherapy had already been treated on and 3 domestic medical linear accelerators with superior installed capacities were chose for research.The ionization chamber and electrometer were used to measure the dose output performance of the linear accelerators on water phantom.The mechanical precision of the linear accelerators was measured with coordinate paper,front pointer,scales and other tools.The radiation performance and multi-leaf collimator positioning accuracy were obtained by PIPSpro5.3.1 and doselab softwares,which provided great conveniences in analyzing the recorded radiation fields taken by solid water and EBT films.Results According to the AAPM TG-142 and the People’s Republic of China Pharmaceutical Industry Standard YY0832.2-2015,a complete set of evaluation criteria for domestic medical linear accelerators had been set up.The evaluation results showed that the accuracy,repeatability and linearity of the output dose of domestic medical linear accelerators are high;that the radiation field isocenters accuracies of gantry,collimator and couch were mostly less than 1 mm;that the average positioning accuracy of jaws and multileaf collimators was less than 0.5 mm;and that the end-to-end deviations of two kinds of domestic accelerators were less than5%.All these results revealed that domestic medical linear accelerators had good basic performances.Conclusion The dose output and treatment accuracy of some domestic medical linear accelerator has already met the basic requirements of stereotactic radiotherapy.However,the relevant radiotherapy units should invest more manpower and corresponding equipments to carry out the quality assurance and quality control of the medical linear accelerator in order to promote stereotactic radiotherapy.