医用直线加速器辐射防护与评价
关键词 医用电子直线加速器; 屏蔽核算; 剂量评价; 环境影响评价5555
毕业设计说明书（毕业论文）外文摘要
Title Radiation Protection and Evaluation of Medical linear Accelerator
Abstract
Objective Calculate the dose rate of protective door and shielding wall of a room with 15MV medical linear accelerator.Base on the dose rate to evaluate the annual effective dose equivalent of radiological workers and the surrounding public. And complete the environmental impact assessment of the accelerator. Methods Choose Varian Clinac iX 15 MV Medical linear Accelerator of The first People's hospital in Yancheng city as the research object. According to the recommendations and requirements of the imminent national standard GBZ /T 201.2, use corresponding formulas and medical accelerator practical parameters to evaluate and analyse the radiation protection ability of the room. Results The largest instantaneous dose rate of room's shielding wall is 2.49μSv/h, and the instantaneous dose rate of protective door is 1.84 u Sv/h. The largest annual effective dose equivalent of radiological workers is 1.58 mSv, and public's annual effective dose equivalent is 0.156 mSv. Conclusions The shielding ability of the linear accelerator room can satisfy the requirements of the national standard. Therefore，the design scheme of the room is feasible. This linear accelerator can be put into medical application when other auxiliary and safety measures are completed.
Keywords Medical linear accelerator; Shielding calculation; Dose evaluation; Environmental impact assessment
目 次
1 引言 1
2 医用直线加速器 2
2.1 简介 2
2.2 工作原理2
2.3 治疗过程 3
2.4 主要污染物4
2.5 污染防治措施5
3 环境影响评价 6
3.1 项目简介 6
3.2 环境现状调查6
3.3 环境问题及保护目标 10
3.4 评价标准10
3.5 机房屏蔽核算及剂量评价12
3.5.1 机房墙体屏蔽设计核算14
3.5.2 机房入口防护门屏蔽核算20
3.5.3 感生放射性污染24
3.5.4 保护目标剂量评价24
3.5.5 安全防护措施评价25
结论 27
致谢 29
参考文献30
1 引言
放射治疗在对恶性肿瘤的治疗中占有重要的作用，大约70%的肿瘤患者需要接受放射治疗。而放射治疗技术的发展与加速器的发展密切相关，当前医用加速器的代表是医用电子直线加速器，它不仅是加速器台数最多的一种，也是各种放射治疗装置中台数最多的一种。
医用电子直线加速器的广泛应用和迅速发展，无疑给人类带来了巨大的利益。但是电离辐射是把双刃剑，各种射线对人体也有损伤作用的一面，不当的和过量的电离辐射照射会引起对人体的危害[1]。因此，电离辐射医学应用的放射防护与安全日益强烈的凸显其重要性和迫切性。依据现行的射线装置分类办法，医用电子直线加速器属于II类射线装置，为中危险射线装置，发生事故时可以使受照人员产生较严重的放射损伤，大剂量照射甚至导致死亡。医用电子直线加速器对工作场所及周围环境产生的辐射水平及其防护问题已引起了社会的普遍注意和关切。配备医用电子直线加速器设备进行放射治疗的各级医疗机构，大多在人口集中的城市中心区域。除了必须充分重视医学放射工作人员的职业照射防护外，还必须关注放射治疗机房周围环境的放射安全，考虑到公众的防护[2]。