MOBETRON移动式术中电子线加速器临床应用

Clinical Use of MOBETRON: A Mobile Electron-Beam Linear Accelerator

目的:分析MOBETRON 2000移动式术中电子线加速器的剂量学特性、日常质量保证数据和治疗参数。方法:使用PTW0.6cc指型电离室、静电计和三维水箱对MOBETRON加速器3档能量进行测量,包括中心轴百分深度剂量和离轴比。利用机器自带的质量保证(quality assurance,QA)设备测量每日QA数据。同时,分析并总结临床46例患者术中放疗治疗参数和操作经验。结果:MOBETRON高能电子线的表面剂量随能量增加而增加;随直径增加,先降低再增加;最大剂量深度Dmax和治疗深度D90随能量增加而增加,随角度增加而降低;实际射程随能量增加而增加;输出剂量稳定性在±3%以内。46例患者顺利完成术中放疗操作,剂量准确,未发生意外。结论:MOBETRON加速器产生的高能电子线具有表面剂量高,剂量学参数稳定的特点,能有效保护靶区后的正常组织,治疗时间短,适合术中暴露肿瘤区域的治疗。

Objective:To analyze the dosimetric properties,quality assurance(QA)data and treatment parameters of MOBETRON 2000,an intraoperative electron radiotherapy accelerator.Methods:The parameters of each energy(6,9 and 12 MeV)in MOBETRON linear accelerator were measured using PTW0.6cc Farmer ionization chamber,dosimetry electrom-eter and 3D blue-water phantom system,including the percentage depth dose and off-axial ratio.At the same time,daily QA data was measured using IntraOP QA equipment.We analyzed and summarized the intraoperative radiotherapy parameters and operational experience of 46 patients in clinical practice.Results:The surface dose of MOBETRON electron beam increased with energy growth.The Dmax and D90 of different diameter applicators also increased with energy augment but decreased with the increase of angle.The practical range increased with the amplification of energy.The output stability satisfied clinical con-dition within±3%limits.46 patients completed treatment successfully in accurate dose,and no accidents occurred.Conclu-sion:The characteristics of high-energy electron beam generated by MOBETRON include high surface dose,stable dosimetry parameters,and short treatment time.It is suitable for the treatment of the exposed tumor area during surgery because it effectively protects normal tissues behind target area.