Optical design of a beam delivery system using a rotator

Abstract

Hadron therapy for cancer is greatly improved by the use of a gantry.A gantry makes it possible to deliver the radiation dose to the tumour from dierent directions, so that the entry dose is spread out.The problem for the machine designer is to make the gantry optics independent of the gantry rotation.This results in complicated matching conditions; especially if the emittances in the two transverse phase spaces are unequal.We recapitulate the theory of a rotator to feed a single gantry and we generalize to beam delivery systems using one rotator to feed several gantries.We give some design examples for rotators and outline some criteria that are important for keeping reasonable beam sizes in the rotators.We give a modular design for a beam delivery system; these modules can be combined in dierent w a ys, to give systems consisting of one rotator and an arbitrary number of gantries.