Ultra-fast imaging for the safe delivery of electron FLASH radiation therapy

摘要 放射治疗是一种辅助治疗，与大多数手术和化疗一起使用， 每四个人中就有一个在他们的一生中被传递。虽然图像引导和适形规划 尽管减少了对健康组织的剂量，但仍然存在组织损伤的实质性风险，这设定了 剂量沉积到肿瘤。最近的一种激进的方法，以尽量减少健康组织的损害， 具有超高剂量率的辐照，被称为FLASH效应。这种治疗以剂量率进行 比传统模式高1000倍，并且通过在100毫秒内提供整个治疗过程， 承诺将辐射引起的毒性降低10- 50%。几个临床中心，包括达特茅斯 希区柯克诊所，证明现有的临床直线加速器可以可逆地转换成超高剂量 速率电子源这种修饰显示出巨大的翻译潜力，以提供电子闪光 （eFLASH）在任何放射治疗中心使用现有的系统。然而，尽管该领域的大多数研究都集中在 在阐明闪光的放射生物学机制方面，减轻闪光风险的工作主要是 未触及，但将是广泛的临床实施的关键。探测监测辐射的新技术 由于闪存的工作时间为毫秒级，这使得传统的 方法不合适。在这个项目中，我们利用了DoseOptics BeamSiteTM系统的独特性， 510（k）批准的单光子照相机，用于监测传统放射治疗， 放射剂量输送的直接视频。放射治疗师使用BeamSite图像来监测辐射 实时交付。临床使用表明，常规监测放射治疗可以揭示次优输送 这可以由治疗师根据需要解决。更重要的是，它提供了一个自动检测光束， 以及患者未对准和输送错误，因此，即使是超快闪存，也具有很强的可扩展性 应用程序.在这个第一阶段的项目中，我们建议开发一个超快版本的BeamSite相机， 以千帧/秒的帧速率跟踪患者的光束，这需要跟上标准的360 Hz射束脉冲速率，以提供急需的射束位置和线性和可扩展的剂量测定， 这些超高的剂量率一旦相机被开发出来，这些方法将在DHMC现有的 临床两用FLASH直线加速器。目前的建议为以下目标提供资源：㈠制定一个 配备优化的基于固件的算法的超快切伦科夫相机的硬件原型，以及 (ii)展示了其在现有eFLASH直线加速器上检测束流偏差和剂量的能力。工作 包括硬件和软件支持和开发，以及达特茅斯希区柯克的eFLASH资源， 为实现这些目标而努力。

Abstract Radiation therapy is a supplementary curative treatment used adjuvant with most surgery and chemotherapy, being delivered to nearly 1 out of every 4 people in their lifetime. While image guidance and conformal planning reduced the dose to healthy tissue, there is still a substantial risk of tissue damage that sets the upper limit of dose deposited to the tumor. A recent radical approach to minimize healthy tissue damage was demonstrated with ultra-high dose rate irradiation, and is known as the FLASH effect. This treatment operates at dose rates 1000x higher than in conventional mode, and by delivering an entire treatment course in 100 millisecond, it promises a reduction of radiation-induced toxicities by 10-50%. Several clinical centers, including Dartmouth Hitchcock Clinic, demonstrated that an existing clinical linac can be reversibly converted into an ultra-high dose rate electron source. This modification shows enormous translational potential to deliver electron FLASH (eFLASH) in any radiotherapy center using existing systems. However, while most research in the field is focused on elucidating the radiobiological mechanisms of FLASH, work towards mitigating the risks of FLASH is largely untouched, yet will be pivotal for wide clinical implementation. New techniques for detection monitoring radiation need to be developed due to the millisecond timescales at which FLASH operates which make traditional methods unsuitable. In this project, we exploit the uniqueness of DoseOptics BeamSiteTM system, a recently 510(k) cleared single photon capable camera designed to monitor conventional radiotherapy providing the first direct videos of the radiation dose delivery. BeamSite images are used by radiation therapists to monitor radiation delivery real-time. Clinical use has shown that routine monitoring of radiotherapy can reveal sub-optimal delivery which can be addressed by the therapists as needed. More importantly, it offers an automatic detection of beam and patient misalignments and delivery errors, and therefore it is very scalable even to the ultra-fast FLASH application. In this Phase I project we propose to develop an ultra-fast version of the BeamSite camera capable of tracking the beam on patients at kiloframe/s frame rate, which is required to keep up with the standard 360 Hz beam pulse rate in order to provide critically needed beam location and a linear and scalable dosimetry at these ultra-high dose rates. Once the camera is developed, these methods will be studied on DHMC’s existing clinical dual-purpose FLASH linac. The current proposal provides resources for the goals of: (i) developing a hardware prototype of an ultra-fast Cherenkov camera equipped with optimized, firmware-based algorithms, and (ii) demonstrating its capabilities for detecting beam deviations and dose on an existing eFLASH linac. The work includes hardware and software support and development, and eFLASH resources at Dartmouth Hitchcock to be leveraged towards these goals.