Shaping of a laser-accelerated proton beam for radiobiology applications via genetic algorithm

TL;DR

This paper presents a genetic algorithm-based method to design a non-flat scattering system that optimizes the beam profile of laser-accelerated protons for radiobiology, improving dose uniformity without reducing flux.

Contribution

It introduces a novel application of genetic algorithms to shape laser-accelerated proton beams, enhancing dose homogeneity for radiobiology applications.

Findings

GA-designed scattering system improves dose uniformity

Magnetic transport system enhances beam mixing

Compared with flat scattering system, optimized system yields better dose profiles

Abstract

Laser-accelerated protons have a great potential for innovative experiments in radiation biology due to the sub-picosecond pulse duration and high dose rate achievable. However, the broad angular divergence makes them not optimal for applications with stringent requirements on dose homogeneity and total flux at the irradiated target. The strategy otherwise adopted to increase the homogeneity is to increase the distance between the source and the irradiation plane or to spread the beam with flat scattering systems or through the transport system itself. Such methods considerably reduce the proton flux and are not optimal for laser-accelerated protons. In this paper we demonstrate the use of a Genetic Algorithm (GA) to design an optimal non-flat scattering system to shape the beam and efficiently flatten the transversal dose distribution at the irradiated target. The system is placed in the magnetic transport system to take advantage of the presence of chromatic focusing elements to further mix the proton trajectories. The effect of a flat scattering system placed after the transport system is also presented for comparison. The general structure of the GA and its application to the shaping of a laser-accelerated proton beam are presented, as well as its application to the optimisation of dose distribution in a water target in air.