Developing Bragg-peak FLASH proton irradiator using permanent magnet synchrotron

A novel Bragg peak FLASH proton radiation therapy facility using the fixed-magnetic-field synchrotron with kinetic energy range between 10 and 250 MeV will be built at Stony Brook University Hospital. The permanent magnet synchrotron has the shape of a racetrack where the two arcs are made of combined nonlinear fields magnets. This design can provide fixed betatron tunes for the extraordinary kinetic energy, and allow FLASH radiation to be delivered at 40 Gy/s in 100 ms. The permanent magnet accelerator should reduce overall operating cost. This facility can fit into a 7 × 11 m² space. As the first step to investigate proton beam lateral profiles and penetration distribution in tissue, we tested physical properties of proton FLASH beams starting from lower energy 28 MeV beam. The beam width was 7.45 mm in both the horizontal and vertical directions. The measured Bragg peak depth was 6.5 mm and peak gap was 8.97 mm. This particular low energy beam distribution would be suitable for the planned small animal studies.