A STUDY OF DISPERSION EFFECTS IN TRANSPORT OF ION-THERAPY BEAMS

Ion beams are an ideal type of radiation for the treatment of well-localized deep-seated tumours. Modern pencil-beam scanning irradiation techniques require precise beam transport including a proper control of the dispersion function of the beam-transport line. Quantitative assessment of dispersion effects in the transport and application of ion-therapy beams at the treatment point is presented in the paper. General specifications for the dispersion function are derived analytically and checked by computer simulations. The results are particularly relevant for the design of rotating ion gantries that have to satisfy a demanding set of ion-optical constraints including the dispersion-control. K e y w o r d s: beam transport, dispersion, ion therapy, medical accelerators, rotating gantry