Geant4 studies of the CNAO facility system for Hadrontherapy treatment of uveal melanoma

The Italian National Centre of Hadrontherapy for Cancer Treatment (CNAO Centro Nazionale di Adroterapia Oncologica) in Pavia, Italy, has started the treatment of selected cancers with the first patients in late 2011. In the coming months at CNAO plans are to activate a new dedicated treatment line for irradiation of uveal melanomas using the available active beam scan. The beam characteristics and the experimental setup should be tuned in order to reach the necessary precision required for such treatments. Collaboration between CNAO foundation, University of Pavia and INFN has started in 2011 to study the feasibility of these specialised treatments with the ai, of implementing a detailed simulation of the beam line and comparing the obtained simulation results with test measurements at CNAO. The goal is to optimise a new dedicated beam line and to find the best conditions for an optimal patient irradiation. The application studied in this paper describes the Geant4 toolkit simulation of the CNAO setup as well as a modelised human eye with a tumour inside. The Geant4 application could be also used to test possible treatment planning systems. Simulation results illustrate the possibility to adapt the CNAO standard transport beam line by optimizing the position of the isocentre and the addition of some passive elements to better shape the beam for this dedicated study.