Superconducting cyclotron for Flash therapy.

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 ∼ 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. [ABSTRACT FROM AUTHOR]