Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States of America.
Department of Radiation Oncology Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong 250000, People's Republic of China.
Phys Med Biol. 2024 Aug 9;69(16). doi: 10.1088/1361-6560/ad69fc.
. The FLASH effect can potentially be used to improve the therapeutic ratio of radiotherapy (RT) through delivery of Ultra-high-dose-rate (UHDR) irradiation. Research is actively being conducted to translate UHDR-RT and for this purpose the Mobetron is capable of producing electron beams at both UHDR and conventional dose rates for FLASH research and translation. This work presents commissioning of an UHDR Mobetron with end-to-end tests developed for preclinical research.. UHDR electron beams were commissioned with an efficient approach utilizing a 3D-printed water tank and film to fully characterize beam characteristics and dependences on field size, pulse width (PW) and pulse repetition frequency (PRF). This commissioning data was used to implement a beam model using the GAMOS Monte Carlo toolkit for the preclinical research. Then, the workflow for preclinical FLASH irradiation was validated with end-to-end tests delivered to a 3D-printed mouse phantom with internal inhomogeneities.PDDs, profiles and output factors acquired with radiochromic films were precisely measured, with a PRF that showed little effect on the UHDR beam energy and spatial characteristics. Increasing PW reduced theand Rby 2.08 mmsand 1.28 mmsrespectively. An end-to-end test of the preclinical research workflow showed that both profiles in head-foot and lateral directions were in good agreement with the MC calculations for the heterogeneous 3D printed mouse phantom with Gamma index above 93% for 2 mm/2% criteria, and 99% for 3 mm/3%.. The UHDR Mobetron is a versatile tool for FLASH preclinical research and this comprehensive beam model and workflow was validated to meet the requirements for conducting translational FLASH research.
FLASH 效应可通过超高速率（UHDR）照射来提高放射治疗（RT）的治疗比。目前正在积极开展 UHDR-RT 的转化研究，为此，MOBETRON 能够以 UHDR 和常规剂量率产生电子束，用于 FLASH 研究和转化。本工作介绍了 UHDR MOBETRON 的调试情况，以及为临床前研究开发的端到端测试。利用 3D 打印水箱和胶片，采用高效方法对 UHDR 电子束进行了调试，以全面表征束特性以及与射野大小、脉冲宽度（PW）和脉冲重复频率（PRF）的依赖性。该调试数据用于使用 GAMOS 蒙特卡罗工具包为临床前研究实施束模型。然后，通过对具有内部不均匀性的 3D 打印小鼠体模进行端到端测试，验证了临床前 FLASH 照射的工作流程。使用放射色迹胶片获得的 PDDs、轮廓和输出因子进行了精确测量，PRF 对 UHDR 束能量和空间特性的影响很小。增加 PW 分别使和 R 减小了 2.08mm 和 1.28mm。临床前研究工作流程的端到端测试表明，在头脚和横向方向上的轮廓与 MC 计算结果吻合良好，对于具有 93%以上的伽马指数的异质 3D 打印小鼠体模，2mm/2%标准下的符合率为 99%，3mm/3%标准下的符合率为 99%。UHDR MOBETRON 是 FLASH 临床前研究的多功能工具，本研究全面的束模型和工作流程已得到验证，可满足开展转化 FLASH 研究的要求。
