Meson factories

The machines built for optimum meson production are commonly called meson factories. The medium-energy proton accelerators with beam intensity of almost 1 mA are able to produce the flux of secondary particles, including pions, muons, neutrinos, and neutrons, which are 10,000 times as intense as those previously available. The advent of meson-producing accelerators has resulted in much works which have practical application, ranging from the development of improved megavoltage therapy machines to the treatment of cow-eye tumors with hyperthermia. The potential advantages of negative pions in cancer therapy include reduced O2 effect and better dose localization as compared to X-ray. In the case of 93 patients treated with pions, the location of target tumors included brain, head and neck, breast, lung, prostate and pancreas, in addition to skin metastases. The recent research in accelerator design has lead to the considerable improvement in the reliability and efficiency. (Yamashita, S.)