New developments of 11C post-accelerated beams for hadron therapy and imaging

Hadron therapy was first proposed in 1946 and is by now widespread throughout the world, as witnessed with the design and construction of the CNAO, HIT, PROSCAN and MedAustron treatment centres, among others. The clinical interest in hadron therapy lies in the fact that it delivers precision treatment of tumours, exploiting the characteristic shape (the Bragg peak) of the energy deposition in the tissues for charged hadrons. In particular, carbon ion therapy is found to be biologically more effective, with respect to protons, on certain types of tumours. Following an approach tested at NIRS in Japan [1], carbon ion therapy treatments based on C-12 could be combined or fully replaced with C-11 PET radioactive ions post-accelerated to the same energy. This approach allows providing a beam for treatment and, at the same time, to collect information on the 3D distributions of the implanted ions by PET imaging. The production of C-11 ion beams can be performed using two methods. A first one is based on the production using compact PET cyclotrons with 10-20 MeV protons via N-14(p,alpha)C-11 reactions following an approach developed at the Lawrence Berkeley National Laboratory [2]. A second route exploits spallation reactions F-19(p,X)C-11 and Na-23(p,X)C-11 on a molten fluoride salt target using the ISOL (isotope separation on-line) technique [3]. This approach can be seriously envisaged at CERN-ISOLDE following recent progresses made on C-11(+) production [4] and proven post-acceleration of pure C-10(3/6+) beams in the REX-ISOLDE linac [5]. Part of the required components is operational in radioactive ion beam facilities or commercial medical PET cyclotrons. The driver could be a 70 MeV, 1.2 mA proton commercial cyclotron, which would lead to 8.1 x 10(7) C-11(6+) per spill. This intensity is appropriate using C-11 ions alone for both imaging and treatment. Here we report on the ongoing feasibility studies of such approach, using the Monte Carlo particle transport code FLUKA [6,7] to simulate pristine Bragg Peaks of C-11, in order to compare its performance with C-12, in the context of hadron therapy. (C) 2016 The Authors. Published by Elsevier B.V.