Contents I. Introduction
There is a raising interest in the medical community to use heavy particles (mainly protons and ions) to irradiate tumor cells [1], because once accelerated to the appropriate energy the danger to the healthy tissues is less than that made by X-rays. There is an increasing number of proton therapy facilities in the world, some of them using ions, being the first ones those in Heidelberg, Germany [2] and Chiba, Japan [3]. The main driving cost of those facilities is the gantry, based on normal magnets in the former case (about 600 tons of overall weight) and superconducting ones in the latter (about 350 tons). It is necessary an additional reduction of weight and complexity to make these facilities affordable for a general use.
