Beam delivery systems for charged particles.

Heavy charged particle therapy, started at research institutes three decades ago, is now on the verge of entering a clinical phase. This phase has resulted from the evolution and development of various beam delivery systems and techniques with existing research accelerators and with newly built accelerators. For the first thirty years, heavy charged particle therapy was administered with a fixed horizontal beam line. In 1991, the first treatment with an isocentric gantry was administered. The development of the isocentric gantry, the newest beam delivery system, and clearly a consequence of all the experience gained at the earlier facilities has many advantages. It offers advantageous physical properties of the particles as well as being equal in the flexibility of dose delivery to the modern photon radiotherapy gantries.