Introduction Welcome Message of Congress Presidents On behalf of the Organizing Committee, we would like to extend our warmest welcome to all colleagues participating in the World Congress on Medical Physics and Biomedical Engineering 2006. We hope you will join us, taking advantage of this opportunity to learn the latest advancements in the field, to reconnect with old friends and meet new ones, and to take in the sights and sounds of Seoul. WC 2006 offers a strong and diverse scientific program covering a wide range of issues and challenges that are currently present in Medical Physics and Biomedical Engineering on the theme of “Imaging the Future Medicine. ” Approximately, 2,500 papers will be presented in oral and poster sessions on the 25 tracks covering around 250 sessions. In addition to the proffered presentations, you will have access to 15 symposium, 4 workshop, 15 short course and 15 continuing education course sponsored by AAPM during the congress. We have also invited numerous speakers from the world. 10 plenary spe- ers and more than 100 invited speakers will give us their perspective on the challenges and opportunities ahead for Medical Physics and Biomedical Engineering and their potential to contribute to improved health care throughout the world. In particular, we wish to extend sincere thanks to the track chairs, session chairs, international advisors and Scientific P- gram Committee members for their hard work and invaluable assistance performed on a voluntary basis in putting the c- gress together over the past year.