Adopting a proactive approach and focusing on emerging radiation-generating technologies, Health Physics in the 21st Century meets the growing need for a presentation of the relevant radiological characteristics and hazards. As such, this monograph discusses those technologies that will affect the health physics and radiation protection profession over the decades to come. After an introductory overview, the second part of this book looks at fission and fusion energy, followed by a section devoted to accelerators, while the final main section deals with radiation on manned space missions. Throughout, the author summarizes the relevant technology and scientific basis, while providing over 200 problems plus solutions to illustrate and amplify the text. Twelve appendices add further background material to support and enrich the topics addressed in the text, making this invaluable reading for students and lecturers in physics, biophysicists, clinical, nuclear and radiation physicists, as well as physicists in industry.