Facilities for radiotherapy with ion beams status and worldwide developments

Forty-five years after the first ion beam therapy in Berkeley around 25,000 cancer patients worldwide have been treated successfully. Ion accelerators, designed for nuclear research, delivered most of this treatment. The first hospital-based facility started operation in 1998 at Loma Linda California, the first for heavier ions at Chiba, Japan in 1994 and the first commercially delivered facilities started operation in 1998 at Kashiwa, Japan. In 2000, the Harvard Medical Centre, Boston, US, will commence operation and several new facilities are planned or under construction worldwide, although none in Australia. This paper will discuss the physical and biological advantages of ion beams over x-rays and electrons. In the treatment of cancer patients ion beam therapy is especially suited for localised tumours in radiation sensitive areas like skull or spine. Heavier ions are also effective in anoxic tumour cells (found around the normally oxygenated cell population). An additional advantage of the heavier carbon or oxygen ions is the possibility of using in situ 'Positron imaging' of the ion range in the patient during the treatment. With modern spot scanning techniques a 3-dimensional target-conform treatment is possible, a technique which minimises radiation exposure to healthy tissue. The available accelerator and beam delivering systems will be discussed in respect of flexibility and simplicity for routine patient treatment in a hospital environment. In conclusion, a possible scheme for an Australian Ion Therapy facility for the 21st century will be outlined.