Achromatic gantry design using fixed-field spiral combined-function magnets

Abstract Arc-therapy and flash therapy are promising proton treatment modalities as they enable further sparing of the healthy tissues surrounding tumor site. They impose strong constraints on beam delivery system rotating gantry structure, in particular providing high dose rate fast energy scanning. Fixed-field achromatic transport lattices potentially satisfy both allowing instant modulation sufficient transmission efficiency while a compact footprint. The presented design study uses fixed-field magnets with spiral edges respecting FFA scaling law. cell structure layout studied simulation integrated gantry. Results optimizations discussed.