[Science and ethics of proton therapy]

Proton therapy delivers a conformed dose to the tumor, while reducing the dose to the surrounding tissues. Its relative biological effectiveness (RBE) is similar to that of conventional radiation, such as X-rays and gamma-rays. Proton therapy was first applied to humans in 1954. Thus for more than 19,000 patients have been treated. The distribution of the diseases to which it has been applied, however, has been quite limited. Although it is now performed at 17 institutions throughout the world, a hospital-based medically dedicated proton therapy system exists at only one institution. Therefore, proton therapy is considered to be an experimental treatment for most malignant diseases, and its equipment is also considered to be underdevelopment situation. In this paper, the project of proton treatment facility at the National Cancer Center (NCC, Kashiwa) is presented. Problems and future direction of our project are also discussed in this article.