Initial Steps Towards a Clinical FLASH Radiotherapy System: Pediatric Whole Brain Irradiation with 40 MeV Electrons at FLASH Dose Rates.
Initial Steps Towards a Clinical FLASH Radiotherapy System: Pediatric Whole Brain Irradiation with 40 MeV Electrons at FLASH Dose Rates.
复制标题
临床闪光放射疗法系统的初步步骤：带有40 MEV电子的小儿整个大脑照射，闪光剂量率。
DOI：
10.1667/rade-20-00069.1
复制
发表时间：
2020-12-01
影响因子：
3.4
通讯作者：
Loo BW
中科院分区：
文献类型：
--
作者：
Breitkreutz DY;Shumail M;Bush KK;Tantawi SG;Maxime PG;Loo BW
在这项工作中，我们研究了使用由实际可实现的直线加速器系统产生的两个横向相对的40 MeV电子束以闪光剂量率提供临床可接受的儿科全脑放射治疗计划的情况。使用EGSnrc蒙特卡罗软件模块BEAMnrc和DOSXYZnrc，使用两个横向相对的40 MeV电子束为一名儿科患者生成全脑放射治疗计划。使用直径为10 cm、SAD为50 cm(定义在脑中线)的发散束模型来模拟电子束相空间文件。电子束的准直使用一个10厘米厚的块，块由5厘米的氧化铝和5厘米的钨组成。为了进行比较，用VARIAN AAA算法计算了一个6 MV的光子计划。电子束参数是基于一种为相位加速器系统设计的新型直线加速器，并由商业6兆瓦速调管供电。对直线加速器性能的计算表明，平均束流至少为6.25GyA，在等中心提供115Gy/S的剂量率，足以产生认知保护的闪光效应。电子平面的均匀性较差，其均匀指数为0.133，而光子平面的指数为0.087。总体而言，40 MeV电子计划的剂量学特征适合治疗。综上所述，本工作中进行的蒙特卡罗模拟表明，两束横向相对的40 MeV电子束可用于闪光剂量率为115GY/S的儿童全脑照射，并可作为实用的临床闪光放射治疗系统的动力，该系统可在不久的将来实施。
In this work, we investigated the delivery of a clinically acceptable pediatric whole brain radiotherapy plan at FLASH dose rates using two lateral opposing 40-MeV electron beams produced by a practically realizable linear accelerator system. The EGSnrc Monte Carlo software modules, BEAMnrc and DOSXYZnrc, were used to generate whole brain radiotherapy plans for a pediatric patient using two lateral opposing 40-MeV electron beams. Electron beam phase space files were simulated using a model of a diverging beam with a diameter of 10 cm at 50 cm SAD (defined at brain midline). The electron beams were collimated using a 10-cm-thick block composed of 5 cm of aluminum oxide and 5 cm of tungsten. For comparison, a 6-MV photon plan was calculated with the Varian AAA algorithm. Electron beam parameters were based on a novel linear accelerator designed for the PHASER system and powered by a commercial 6-MW klystron. Calculations of the linear accelerator’s performance indicated an average beam current of at least 6.25 μA, providing a dose rate of 115 Gy/s at isocenter, high enough for cognition-sparing FLASH effects. The electron plan was less homogenous with a homogeneity index of 0.133 compared to the photon plan’s index of 0.087. Overall, the dosimetric characteristics of the 40-MeV electron plan were suitable for treatment. In conclusion, Monte Carlo simulations performed in this work indicate that two lateral opposing 40-MeV electron beams can be used for pediatric whole brain irradiation at FLASH dose rates of >115 Gy/s and serve as motivation for a practical clinical FLASH radiotherapy system, which can be implemented in the near future.