无均整器型加速器治疗室中子剂量分布

发布时间：2018-06-07 17:53

本文选题：移除均整器技术 + MV　；参考：《中华肿瘤防治杂志》2017年17期

【摘要】：目的调强放疗技术极大改善了放疗计划质量,但相对适形放疗也随之增加了治疗出束剂量及照射时间,移除均整器(flattening filter free,FFF)技术能在保持计划质量的前提下减少照射时间。本研究测量和分析瓦里安TrueBeam型加速器常规剂量率有均整器(flattening filter,FF)模式和超高剂量率FFF模式下中子累积剂量和持续时间,及其在机房的分布规律,为临床使用提供参考。方法机房内选取加速器治疗高度等中心技师摆位处、治疗床远端、迷路近端和防护门内侧4个位置,设置5cm×5cm、10cm×10cm和30cm×30cm 3种射野面积,出束剂量分别为500、1 000和2 000 MU,等中心位置放置30cm厚度固体水模体模拟患者身体,在10 MV X射线600 MU/min常规剂量率FF模式和2 400 MU/min超高剂量率FFF模式下,测量中子的累积剂量及消退时间,同时在机房外选取防护门外、操作室和主防护墙中心3个位置进行测量。结果中子累积剂量与射野面积大小呈反比;距离靶中心越近,中子累积剂量越大,机房内中子累积最大位置为治疗床远端;中子累积剂量FF模式高于FFF模式,差异有统计学意义,P0.05。中子消退时间与出束剂量成正比;相同条件FFF模式下的中子消退时间小于FF模式,距离中心靶位点越远中子消退时间越快。结论加速器移除均整器后中子累积剂量及持续时间明显下降,有益于患者及工作人员的辐射防护;现有加速器机房防中子设计同样适用于FFF模式加速器。
[Abstract]:Objective intensity modulated radiotherapy (IMRT) has greatly improved the quality of radiotherapy plan, but the relative conformal radiotherapy has also increased the dose and time of irradiation. Removing the whole attening filter free FFFs can reduce the irradiation time while maintaining the planned quality. In this study, we measured and analyzed the neutron cumulative dose and duration of conventional dose rate in Varian TrueBeam accelerator in FFFF mode and FFF mode, and their distribution in computer room, which provided reference for clinical use. Methods in the computer room, four positions were selected as the center technician of accelerator treatment height, the distal end of the bed, the proximal end of labyrinth and the medial side of the protective door. The three kinds of field areas, 5cm 脳 5 cm ~ (-1) 10 cm 脳 10cm and 30cm 脳 30cm, were set up. The outbeam doses were 500 and 2 000 MUs, respectively. The 30cm thickness solid water motifs were placed in the isocentric position to simulate the patient's body. In the 10MV X ray 600MU / min conventional dose rate FF mode and the 2 400 MUP / min ultrahigh dose rate FFF mode, there was no significant difference between the two models. The cumulative dose and extinction time of neutrons were measured. At the same time, three positions were selected outside the machine room, such as the protective door, the operation room and the center of the main protective wall. Results the neutron accumulative dose was inversely proportional to the size of the field area, the closer to the target center, the greater the neutron cumulative dose, the greater the maximum position of neutron accumulation in the machine room was the distal end of the therapeutic bed, and the FF mode of neutron cumulative dose was higher than the FFF mode. The difference was statistically significant (P 0.05). The neutron extinction time is proportional to the beam dose, and the time of neutron extinction is smaller than that of FF model under the same condition, and the farther away from the central target, the faster the neutron extinction time. Conclusion the neutron accumulative dose and duration after the removal of the accelerator are obviously decreased, which is beneficial to the radiation protection of patients and staff, and the existing neutron protection design of the accelerator room is also suitable for the FFF mode accelerator.
【作者单位】：郑州大学附属肿瘤医院放疗科;中山大学肿瘤防治中心放疗科·华南肿瘤学国家重点实验室·肿瘤医学协同创新中心;河南省职业病防治研究院放射卫生科;
【分类号】：R730.55

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