High dose-per-pulse electron beam dosimetry: Commissioning of the Oriatron eRT6 prototype linear accelerator for preclinical use
High dose-per-pulse electron beam dosimetry: Commissioning of the Oriatron eRT6 prototype linear accelerator for preclinical use
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DOI：
10.1002/mp.12713
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发表时间：
2018-02-01
期刊：
影响因子：
3.8
通讯作者：
Bailat, Claude
中科院分区：
文献类型：
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作者：
Jaccard, Maud;Duran, Maria Teresa;Bailat, Claude
目的：Oriatron eRT6是一台实验性的高脉冲剂量直线加速器，用于发射剂量率从几GY/分钟到数百GY/S不等的电子束。它是为了在临床前和认知研究的背景下研究高脉冲剂量/剂量率电子束的放射生物学效应而建造的。在这项工作中，我们报告了Oriatron eRT6原型直线加速器的调试和束流监测。材料和方法：对束流进行了不同步骤的表征。通过20个月的重复测量来研究输出的稳定性。分析了时间电子脉冲宽度、脉冲重复频率和脉冲幅度等束流参数变化引起的相对输出变化。最后，测量了两种不同束流设置下的深度剂量曲线和视野大小，其中一束具有常规放射治疗剂量率，另一束具有高得多的剂量率。测量是用GaF-铬EBT3薄膜和PTW高级马库斯电离室进行的。此外，我们还开发了一套基于位于波导束出口的感应环信号和来自石墨束准直器的信号的束流监测系统。结果：重复测量的输出具有良好的稳定性，标准偏差小于1%。然而，观察到了光束输出不可忽略的逐日变化。根据剂量率的不同，这些输出变化显示出不同的趋势。对相对输出随不同束流参数变化的分析表明，在给定的配置下，剂量率可以可靠地在三个数量级内变化。此外，还观察到了参数之间的相互依赖对输出变化的影响。束流能量和射野大小对剂量率有轻微的依赖性，主要适用于小动物照射。只要电子脉冲幅度保持在给定的阈值以上，束流监测系统就能够以可重复的方式测量离开机器的电子的总电荷。此外，我们还能够将监测系统测量的电荷与固体水模体中的吸收剂量联系起来。结论：Oriatron eRT6已成功投入临床前使用，目前正在全面运行，并正在进行高剂量/脉冲照射的放射生物学效应研究。(C)2017年美国医学物理学家协会
Purpose: The Oriatron eRT6 is an experimental high dose-per-pulse linear accelerator (linac) which was designed to deliver an electron beam with variable dose-rates, ranging from a few Gy/min up to hundreds of Gy/s. It was built to study the radiobiological effects of high dose-per-pulse/dose-rate electron beam irradiation, in the context of preclinical and cognitive studies. In this work, we report on the commissioning and beam monitoring of the Oriatron eRT6 prototype linac.Materials and Methods: The beam was characterized in different steps. The output stability was studied by performing repeated measurements over a period of 20 months. The relative output variations caused by changing beam parameters, such as the temporal electron pulse width, the pulse repetition frequency and the pulse amplitude were also analyzed. Finally, depth dose curves and field sizes were measured for two different beam settings, resulting in one beam with a conventional radiotherapy dose-rate and one with a much higher dose-rate. Measurements were performed with Gaf-chromic EBT3 films and with a PTW Advanced Markus ionization chamber. In addition, we developed a beam current monitoring system based on the signals from an induction torus positioned at the beam exit of the waveguide and from a graphite beam collimator.Results: The stability of the output over repeated measurements was found to be good, with a standard deviation smaller than 1%. However, non-negligible day-to-day variations of the beam output were observed. Those output variations showed different trends depending on the dose-rate. The analysis of the relative output variation as a function of various beam parameters showed that in a given configuration, the dose-rate could be reliably varied over three orders of magnitude. Interdependence effects on the output variation between the parameters were also observed. The beam energy and field size were found to be slightly dose-rate-dependent and suitable mainly for small animal irradiation. The beam monitoring system was able to measure in a reproducible way the total charge of electrons that exit the machine, as long as the electron pulse amplitude remains above a given threshold. Furthermore, we were able to relate the charge measured with the monitoring system to the absorbed dose in a solid water phantom.Conclusion: The Oriatron eRT6 was successfully commissioned for preclinical use and is currently in full operation, with studies being performed on the radiobiological effects of high dose-per-pulse irradiation. (C) 2017 American Association of Physicists in Medicine