Recent applications of Synchrotrons in cancer therapy with Carbon Ions

Abstract

As shown in Table 1, accelerators originally designed for scientific research have found a large number of industrial and medical applications. The main medical applications besides radioactive isotope production with cyclotrons are the electron linacs of a few MeV for radiotherapy of deep seated tumours. Every year in the developed countries about 40,000 people out of 1 million inhabitants are diagnosed as having cancer. About 50% of these patients are treated with radiation, mainly high energy photons produced by electron linacs. In 90% of the cases the electron beam is converted to Bremsstrahlung photons. These photon beams (called “X-rays” by medical doctors) have replaced the low energy X-rays and the 60Co gamma radiation because of a better depth-dose distribution (Fig. 1). Due to the fact that Compton-electrons go forward with a few centimetre range, the dose increases at the entrance (build-up effect) to a maximum value at 3-4 cm below the skin. This increase is followed by a shallow exponential decay for greater depth.