热释光剂量片测量肺部肿瘤放疗剂量的方法

摘要

目的:研究LiF(Mg、Cu、P)热释光剂量片(TLD)在临床肿瘤放疗测量要求的筛选方法.方法:应用60Coγ射线和6 MVX射线,开展TLD分散性、重复性和剂量响应实验,筛选出符合临床肿瘤放疗要求的TLD.根据临床放射治疗需要,将筛选出符合临床要求的TLD分别用称量纸封装并依次编号粘贴在仿真模体处,将粘贴有TLD模体置于6MVX射线加速器照射,验证仿真模体肺部靶区外的剂量.结果:LiF(Mg、Cu、P)TLD重复性和分散性误差控制在±3％以内;用6MVX射线照射粘贴有TLD的模体,测量的TLD剂量值和治疗计划系统值的偏差与TLD所处位置剂量大小有关,当剂量大于62 mGy时,两者符合较好,其差别小于5％;当剂量远小于62 mGy时,其差别明显偏大.结论:在合适剂量范围内用TLD验证肺部肿瘤放疗剂量的方法准确可靠、经济适用,得到国际原子能机构的认可,可广泛应用于肿瘤放疗的剂量测量.%Objective To explore the screening method of LiF (Mg,Cu,P) thermo luminescent dosimeter (TLD) for achieving the measurement standard of tumor radiotherapy.Methods The experiments on the dispersion,repeatability and dose response of TLD were carried out by using 60Co γ ray and 6 MV X-ray beams to screen out the TLD which met the requirements of clinical tumor radiotherapy.According to clinical radiotherapy needs,the chosen TLD was packed by weighing paper,numbered consecutively and pasted onto the different positions of anthropomorphic phantom in sequence.The phantoms pasted with TLD were radiated by 6 MV X-ray accelerator to verify the dose accuracy outside the target volume of phantom.Results The errors of the repeatability and dispersion of TLD were within ±3％.When the phantoms pasted with TLD were radiated by 6 MV X-ray beams,the relative deviation between the TLD absorption dose value and treatment plan system theoretical value depended on the dose value of TLD position.When the dose value was larger than 62 mGy,the relative deviation between the two methods was less than 5％.When the dose was less than 62 mGy,the discrepancy was significantly larger.Conclusion Within the scope of the appropriate dose,the TLD method is reliable,facile and economical for measuring and verifying the dose of lung tumor.And the TLD method can be widely applied to determine the dose of tumor radiotherapy for the TLD method has been recognized by the intemational atomic energy agency.