移动式术中放疗电子加速器手术室剂量场与防护研究

发布时间：2018-04-27 01:22

  本文选题：术中放疗 + 移动式加速器　； 参考：《复旦大学》2013年硕士论文

【摘要】：[目的] 随着移动式术中放疗电子加速器在术中放疗中的日益广泛应用,进一步规范移动式术中放疗电子加速器的科学使用和防护最优化,并制定相应卫生防护标准是十分必要的。本论文旨在通过对术中放疗手术室内外场所在加速器不同能量、不同水平高度和不同方位角度时的剂量分布特征研究,为制定相应防护措施与标准提供可信的科学研究和基础数据。以规范移动式术中放疗电子加速器的合理正当使用,确保相关放射工作人员与周围人员的健康和安全。 [方法] 本研究采用热释光剂量计(TLD)三维空间布点的方法,对移动式术中放疗电子加速器手术室内的剂量场进行了测量。首先对热释光剂量片在使用前进行了筛选,使得分散性小于2%,整个剂量测量系统在使用前经过上海计量测试技术研究院刻度校准。把处理好的将热释光剂量计进行退火处理,将退火后的热释光剂量计三个一组放入透明硅胶管中并编号。然后以移动加速器(Mobetron)射线中心轴为中心轴,分别在50cm,100cm,150cm,200cm四个高度平面上以米字型放射状围绕加速器中心轴每隔45°呈直线布放。距中心轴每隔50cm处分别布放热释光剂量计；在事先标记好的所有位置上布放好剂量计组。加速器机头和机架均处设为0°；辐射场分布测量时一律采用10cm直径、0°端面限光筒；下方连接一专用圆柱形聚乙烯模体(13.5cm*8.5cm),把Mobetron移动式术中放疗电子加速器分别在4、6、9、12MeV4个能量档(其中最常用能量9MeV重点测量)的条件,以10Gy/min剂量率出束1Min后读出剂量计。在手术室内还用电离室剂量计在个别点进行了剂量数据比较。对手术室外四周与上下楼层进行了多次外照射防护剂量检测,综合分析考虑移动式电子加速器的剂量场分布特点。 [结果] 在移动式电子加速器(Mobetron)以10Gy/min剂量率出束1Min条件下,最常用能量档9MeV时,高度为100cm的平面上,距中心参考点50、100、150和200cm处的剂量当量平均值分别为1.69×103、7.56×102、3.95x102和2.41×102μSv；在距中心参考点50cm不同角度上的剂量与平均值最大相差9.1%。9MeV时50、100、150和200cm4个高度平面各方向距中心轴100cm处,平均剂量分别为5.27x102、7.56x102、5.70x102和1.41×102μSv。而4、6、9和12MeV在100cm高度平面90°上,距中心轴100cm处的剂量分别为5.73×101、4.86×102、6.89×102和7.81×102μSv。距离中心轴300cm以上时,辐射剂量明显下降,一般低于100μSv,300cm外的变化则趋于一致,距离中心轴600cm处最小值为14.8μSv。 [结论] 本研究表明术中放疗加速器手术室内部辐射场具有如下剂量特征：同一能量时,同一平面各角度上剂量都随距离增大呈幂指数衰减；同一高度平面,不同角度的剂量分布基本一致。不同高度平面上,100cm平面的剂量最大。不同能量档,剂量随能量的增高而增大。发现加速器在不同能量(4、6、9、12MeV),不同水平高度(0.5m、1.0m、1.5m、2.0m),在手术室内不同方位(45°、90°、135°、180°),其距离加速器中心轴的不同距离(1m、2m、3m、4m、5m、6m)之间的剂量率变化规律均显示在距加速器中心轴为3m时,手术室内该处剂量率即明显降低,并随之趋向幅度较小的平缓下降。故认为距中心轴3m即为剂量率明显降低的转折点。综合考虑上述术中放射治疗手术室内的剂量分布特点,并以此为标准编制提供相应依据,提出术中放射治疗手术室面积应不小于36m2,层高应不小于3.5m,加速器在手术室内的定位点除外墙外应距各侧墙体不小于3m的相关建议。并综合考虑手术室承重情况,经济实力和易于实现操作等因素,给出了移动式电子加速器在术中放射治疗中的放射防护综合要求。
[Abstract]:[Objective]
With the increasing application of the electron accelerator in the intraoperative radiotherapy, it is necessary to further standardize the scientific use and protection of the electronic accelerator in the mobile operation, and to establish the corresponding health protection standards. This paper aims to pass the different energy of the accelerator in the operation of the intraoperative radiotherapy. The dose distribution characteristics of different levels and different azimuth angles are studied to provide reliable scientific research and basic data for the formulation of corresponding protective measures and standards to standardize the rational and proper use of the electronic accelerator in the mobile operation and to ensure the health and safety of the related workers and the people around them.
[method]
In this study, the method of three-dimensional space distribution of the thermoluminescence dosimeter (TLD) was used to measure the dose field in the operating room of the electron accelerator in the mobile operation. First, the thermoluminescence dose tablets were screened before use, making the dispersion less than 2%. The whole dose measurement system was used before the Shanghai Metrology Institute. Calibration. The annealed thermoluminescence dosimeters are annealed and three groups of annealed thermoluminescence dosimeters are placed in the transparent silicon tube and numbered. Then the central axis of the Mobetron ray center axis is placed on the four height planes of the 50cm, 100cm, 150cm, 200cm, and the accelerator is radiated around the accelerator. The center axis is arranged in a straight line every 45 degrees. The heat release dosimeter is distributed every 50cm at the center axis, and the dosimeter is distributed in all positions marked in advance. The accelerator head and the frame are set to 0 degrees; the radiation field distribution is measured with the 10cm diameter and the 0 degree end face limit cylinder; the lower part is connected with a special cylindrical polyb. The 13.5cm*8.5cm, the Mobetron mobile radiotherapy electron accelerator in 4,6,9,12MeV4 energy files (the most commonly used energy 9MeV, which is the most commonly used energy measurement), is used to read out the dosimeters after a 10Gy/min dose rate of 1Min. In the operating room, the ionization chamber dosimeter is also used to compare the dose data at the individual point. Four Multiple doses of external radiation protection were tested in weekly and upper floors, and the distribution characteristics of dose fields in mobile electron accelerators were comprehensively analyzed.
[results]
In the mobile electron accelerator (Mobetron), under the 10Gy/min dose rate of 1Min, the most commonly used energy file 9MeV, on a plane with a height of 100cm, the average dose equivalent of 50100150 and 200cm at the center reference point is 1.69 * 103,7.56 x 102,3.95x102 and 2.41 * 102 micron respectively, and the dose at different angles from the center reference point 50cm. The maximum difference of 9.1%.9MeV between the 50100150 and 200cm4 height planes at the center axis 100cm, the average dose is 5.27x102,7.56x102,5.70x102 and 1.41 x 102 mu Sv., 4,6,9 and 12MeV at the 100cm height plane 90 degrees, and the dosage from the center axis 100cm is 5.73 x 101,4.86 x 102,6.89 x 102 and 7.81 * 102 micron Sv. distances, respectively. When the central axis is above 300cm, the radiation dose decreases obviously, generally less than 100 Sv, and the change outside 300cm tends to be consistent. The minimum distance from the central axis 600cm is 14.8 Sv..
[Conclusion]
This study shows that the radiation field of the intraoperative radiotherapy accelerator has the following dose characteristics: the same energy, the dose on the same plane is exponentially attenuated with the distance; the dose distribution of the different angles is basically the same at the same height plane. The dose of the 100cm plane is the largest on the plane of different heights. Different energy files and agents The quantity of the accelerator at different energy (4,6,9,12MeV), different level (0.5m, 1.0m, 1.5m, 2.0m) in different directions (45, 90, 135, 180) in the operating room (1m, 2m, 3M, 4m, 5m, 6m) of the accelerator was found at the center axis of the accelerator at the center axis of the accelerator. The dose rate of the operating room was obviously reduced, and the trend was smaller. Therefore, it was considered that the distance from the center axis 3M was the turning point of the dose rate obviously decreasing. The product should be not less than 36m2, the height of the layer should be not less than 3.5m, the relative suggestion that the accelerator should be located in the operating room except the outer wall is not less than 3m, and the factors such as the load-bearing situation in the operation room, the economic strength and the easy operation are taken into consideration, and the radiation protection of the mobile electronic accelerator in the intraoperative radiotherapy is given. Ask.

【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R730.55;R146

【共引文献】

中国期刊全文数据库 前4条

1 徐鹏;程素洁;;术中放疗与外科手术联合治疗骨恶性肿瘤临床研究[J];中国辐射卫生;2014年05期

2 冯林春;马林;韦立新;曲宝林;杨东;徐寿平;;单次大剂量照射大鼠头颈部后组织的病理改变[J];肿瘤学杂志;2008年07期

3 鞠忠建;巩汉顺;王运来;;Mobetron移动式术中放疗加速器的短期稳定性分析[J];医疗卫生装备;2010年11期

4 鞠忠建;巩汉顺;王运来;;可移动式术中放射治疗加速器(Mobetron)长期稳定性分析[J];中国医学物理学杂志;2010年04期

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