Flash radiotherapy is a technology that could modify the way radiotherapy is delivered in the future. Radiotherapy’s main goal is delivering dose to the tumor while sparing the surrounding healthy tissues. The Flash scheme utilizes much higher dose rates in much shorter irradiation times compared to conventional radiotherapy. In this context, the high energy proton machine (220–230 MeV) to irradiate deeply sited tumor should provide output beam intensity of tens and hundred microA in pulse regime. The best candidate in this sense would be an isochronous cyclotron. But unfortunately, all existing facilities of the cyclotron type have substantially lower beam current in the indicated energy range. To meet ultra-high intensity requirement, an external injection to the cyclotron could be tried. But again, none of operational cyclotrons with energy $\sim$230 MeV has an external ion source installed. So, the design of the accelerator foreseen is quite a challenge due to many difficult technical problems to be solved on its way. In this paper the results of detailed computer modeling of a compact cyclotron intended for Flash radiotherapy are given. The superconducting technology for the cyclotron magnet design is selected to substantially reduce the weight and size of the facility. The outline of the main cyclotron systems with parameters obtained by scrutinized beam dynamics simulations in spatial field distributions and taking into account the beam space charge effects is given.

闪光放疗是一项可以改变未来放疗方式的技术。放射疗法的主要目标是向肿瘤提供剂量，同时保留周围的健康组织。与常规放射疗法相比，闪光方案在短得多的照射时间内利用了更高的剂量率。在这种情况下，用于照射深处肿瘤的高能质子机（220–230 MeV）应在脉冲状态下提供数十微安的输出光束强度。从这个意义上说，最好的候选者是同步回旋加速器。但是不幸的是，回旋加速器类型的所有现有设备在指示的能量范围内具有明显较低的束流。为了满足超高强度要求，可以尝试向回旋加速器进行外部注入。但是同样，没有运行中的回旋加速器有能量$〜$230 MeV安装了外部离子源。因此，由于要解决许多加速的技术难题，预见到的加速器的设计是一个很大的挑战。本文给出了用于闪光放疗的紧凑型回旋加速器的详细计算机建模结果。选择用于回旋加速器磁铁的超导技术，可以大大减少设备的重量和尺寸。给出了主要回旋加速器系统的轮廓，其参数通过在空间场分布中进行仔细的射束动力学模拟得到，并考虑了射束的空间电荷效应。