Preface
It is my great pleasure to publish the Annual Report, NIRS 2000. This report contains all of the accomplishments of NIRS, which includes rsearch and investigations, medical practice, training and technology assistance that NIRS performed during fiscal year 2000 (from April 2000 to March 2001).
This is NIRS's last year as a national research institute under the direct auspices of the Science and Technology Agency of Japan as well as the end of the 20th century. As a part of the national administrative reform, the Sciene and Technology Agency merged with the Ministry of Educaion, Culture and Sport to form the Ministry of Education, Culture, Sports, Scinece and Technology(MEXT) as of January 6, 2001. Then, as of April 1, 2001, NIRS was reborn as an independent corporative body, "dokuritsu gyousei houjin" in Japaese. The name of the Institute remains the same in both Japanese and English. In praparing for the reform, tremendous efforts were made by all staff members of NIRS, spending much time. It is my pleasure to report that 266 original articles were published in scientific journals and 569 oral presentations were made during this busy year. Details of those research acitvities are summarized in this volume for those interested. I would like to mention a few topical issues among them.
Clinical trials of heavy-ion radiotherapy for cancer have been performed for 7 years. In total, 946 cancer patients were registered by March, 2001. Promising results were obtained with good local control and rare side effects. This therapy may prove to be particularly useful for heads and neck cancers, lung caicinomas, bone and soft tissue malignanacies, prostate carcinomas and uterine cervical cancers. Detailed results were reported at the Net Work Panel of Heavy Ion Radiotheraoy held in August, 2000 and March, 2001, which are open to the public. A certain amount of progress was made in the application process as a "highly advanced medical procedure".
Research activities on radiation-sensitive genes and gene-expression profiles were remarkably promoted. Further progress is expected in the year 2001. The installed PIXE machine made it possible to implement irradiation experiments with micron-level radiation beams. The radon research building was completed at the end of the year 2000, which will promote radon research tremendously.
After a criticality accident occurred at the JCO uranium processing plant in Tokai village, NIRS has been involved in various activities related to the accident, including medical treatment, monitoring environments, care of inhabitants who suffered from anxiety, etc. A comprehensive report on the activites and involvement of NIRS has been published. The annual environment seminar dealt with "Environmental monitoring and radiation-dose estimates of the criticality accident at a uranium processing plant". An international symposium on medical trearments of 3 heavily exposed workers at the criticality accident was held in December, 2000. An NIRS symposium on the "New Development of Molecular Imaging" was held to commemorte the opening of the diagnostic imaging research building. Those as well as many other meetings served for the close communication of researchers from both inside and outside of NIRS.
As an annual event, many people who had served NIRS for many years as scientists and administrative staff left the institute after having reached the retirement age. I would lilke to express my sincere gratitude with respect for their great efforts and contributions to the progress of science and technology.
I would like to finish this note with heartfelt thanks for the cooperation and advice during fiscal year 2000. I also ask for continuous support of the research activities to be perfoemed in accordance with the mid-term 5-year action plan starting from April, 2001.

Yasuhito Sasaki, M. D., Ph. D.
President