Laser-driven time-limited light-sail acceleration of protons for tumor radiotherapy

A laser-driven time-limited light-sail acceleration scheme for proton tumor radiotherapy is proposed, where a whole spread-out Bragg peak (SOBP) dose delivery to the tumor region can be achieved with a single laser shot. By using a proper match of laser and ultrathin foil target parameters, proton light-sail acceleration terminates immaturely before the transverse instability grows up, resulting in the production of a proton beam with the required highly peaked energy spectrum and sufficiently large particle number. A self-consistent combination of three-dimensional particle-in-cell simulations and GEANT4 microdosimetry simulations in a water phantom model demonstrates that our scheme is able to deliver a single-shot SOBP dose up to 1.76 Gy to cubic-centimeter-scale volumes on a nanosecond timescale for shallow-seated tumors and around 0.56 Gy for deep-seated tumors, where the deviations of dose equivalent in the flat SOBP region are both within the clinically acceptable range.