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， 在他们的一生中，几乎每4个人中就有1个被递送到手中。而图像制导和保形规划 虽然减少了对健康组织的剂量，但仍有相当大的组织损伤风险，这设定了 沉积在肿瘤上的剂量。最近展示了一种将健康组织损害降至最低的激进方法。 具有超高剂量率照射，并被称为闪光效应。这种治疗是以剂量率进行的。 比传统模式高1000倍，通过在100毫秒内提供整个疗程，它 承诺将辐射毒性降低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为超高剂量 额定电子源。这一改进显示出巨大的平移潜力，可以提供电子闪光 (EFlash)在使用现有系统的任何放射治疗中心。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，减少闪光风险的工作主要是 尚未触及，但将是广泛临床应用的关键。探测和监测辐射的新技术 由于闪存以毫秒级的时间尺度运行，这使得传统的 方法不合适。在这个项目中，我们开发了DoseOptics BeamSiteTM系统的独特性，该系统是最近推出的一种 510(K)清晰单光子相机，旨在监控传统放射治疗，提供第一个 辐射剂量传递的直接视频。放射治疗师使用BeamSite图像来监测辐射 实时交付。临床应用表明，放射治疗的常规监测可以发现不理想的治疗方案。 这可以由治疗师根据需要来解决。更重要的是，它提供了对光束的自动检测 和患者错位和传输错误，因此即使到超快闪存也非常可扩展 申请。在这个第一阶段的项目中，我们建议开发一个超高速版本的BeamSite相机，该相机能够 以千帧/S帧速率跟踪患者的波束，这是跟上标准360的要求 Hz束脉冲率，以提供急需的束流位置和线性且可缩放的剂量测量 这些超高的剂量率。一旦相机开发完成，这些方法将在DHMC现有的基础上进行研究 临床两用闪光直线加速器。目前的提案为以下目标提供了资源：(1)制定 配备了优化的、基于固件的算法的超高速切伦科夫相机的硬件原型，以及 (2)展示其在现有eFlash直线加速器上检测光束偏差和剂量的能力。这项工作 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 为实现这些目标发挥杠杆作用。

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.