Abstract ID: 164 Detector MC study for measurement of nuclear reaction cross section relevant in particle therapy

Abstract

In protontherapy proton beams are used to treat deep-seated tumors, exploiting the charged particles characteristic depth-dose deposition profile. In clinical practice a constant RBE equal to 1.1 is adopted, regardless of the demonstrated RBE variations [1] , which depends on physical and biological parameters. Among other mechanisms, also nuclear interactions might influence the proton RBE due to secondary heavier particles produced by target fragmentation that can significantly contribute to the total dose. Nuclear interactions especially affect the dose delivered in the entry channel, corresponding to healthy tissues preceding the tumor region [2] . As a consequence, an unwanted and undetermined increase of normal tissues complications probability (NTCP) may occur. At present, experimental data on target fragmentation are scarce. In fact, at therapeutic proton beam energy, fragments identification would be difficult due to their low energy and short range. The main goal of the FOOT (FragmentatiOn Of Target) experiment of INFN is to measure fragment production cross sections, to improve the proton radiobiological characterization, the NTCP control and also the nuclear models adopted By Monte Carlo codes. Target ( 16 O and 12 C nuclei) fragmentation induced by 150–250 AMeV proton beams will be studied via an inverse kinematic strategy: 16 O and 12 C beams impinge on hydrocarbon and graphite targets to provide, by subtraction, fragmentation cross sections on hydrogen. A dedicated experimental setup is currently being developed and optimized. A magnetic spectrometer, a Δ E detector with TOF capabilities and a calorimeter will be used to measure the fragments momenta, Δ E, TOF and kinetic energy. In this work we will present the results of a Monte Carlo study, based on the FLUKA code [3] , which aims to evaluate the detector performance and the expected resolution on fragment identification and on the nuclear cross sections relevant for charged particle therapy. We shall also present a preliminary study of the expected predicted differential cross sections for the production of different fragments on the basis of the physics models of FLUKA.