后装治疗机施源管角度变化对出源精度及放疗剂量影响分析  

The influence of applicator angles on location of radioactive source and dosimetry in Brachytherapy

作　　者：徐金济[1] 蔡倩倩 成俊[1] 周春 XU Jin-ji.(Department of Radiation Oncology, Nantong No. 3 hospital of Nantong University, Nantong, Jiangsu, 226006, China)

机构地区：[1]南通大学附属南通第三人民医院放疗科,江苏226006

出　　处：《齐齐哈尔医学院学报》2017年第24期2922-2923,共2页Journal of Qiqihar Medical University

摘　　要：目的分析后装施源管在放疗过程中的角度变化对后装放射源出源精度及剂量的影响,为临床放疗计划设定提供参考。方法设定0°至90°每间隔10°一组共10组位置,利用自制模板,将施源管按选区角度弯曲,利用高清摄像机多次观测出源结果,计算相应误差。剂量设定为参考深度10 mm处500c Gy,吐源长度1100 mm,分析吐源误差造成的参考点剂量变化与原治疗计划结果比较。结果经过观察,施源管弯曲角度在0°至90°变化范围内,随着角度增加,吐源长度在减小,放射源出源误差最大1.5 mm;参考点剂量因此最大偏差122.8 c Gy,达到计划设定剂量的24.48%。结论后装治疗过程中随着施源管弧度变化,放射源走位精度以及放疗剂量也随之改变,因为后装放射源近似为点源,剂量梯度变化大,进而影响靶区剂量分布及周围危机器官剂量。临床治疗时应尽可能避免施源管出现较大的角度弯曲。Objective To analyze the effect of source applicator angle changes on place accuracy and dosimetry,and to provide evidence for clinical treat plans. Methods Ten angle positions from 0° to 90° were spaced by 10°,and the applicator was bended with a template at each degree,the determination of source position was recorded by HD video camera,playback the video Recording and account the setup errors. The reference depth was set to 10 mm,and the prescription was 500 c Gy. The source position set to 1100 mm. Compared with the original plan,and analysis the effect of dosimetry with setup errors. Results The applicator bended from 0° to90°,the distance of source position decreased as angles increasing. The biggest setup error was 1.5 mm,and the dose of reference point deviation reached 122.8 c Gy,about 24.48% of plan.Conclusions The source position was varied with different angle,and the dosimetry changes too. the radioactive source is similar to a point source,and the gradient of dosimetry varied widely. Little changes of setup errors may lead to big dosimetry changes of PTV coverage and normal tissues. So the applicator should avoid big angle changed in brachytherapy.

关 键 词：后装治疗 施源管 角度 剂量 误差 

分 类 号：R812[医药卫生—放射医学]