In Zurich at the 7th International Annual Meeting of the Society of Nuclear Hedicine in Europe, held in 1969, a group of young scientists from eleven countries dedicated some papers to the memory of Georg von Hevesy. The papers were published in a book entitled "Frontiers of Nuclear Medicine" (Springer-verlag Berlin, Heidelberg, New York). On the occasion of the Second International World Congress of Nuclear Medicine and Biology held in 1978 in Washington D.C., under the presidency of Henry N.Wagner, Jr., a group of young scientists again dedicated important papers from the Congress to the memory of Georg von Hevesy. This book consists of these papers, which present new results in the field of Nuclear Medicine reported by physicians, physicists, chemists, engineers, and computer scientists. The Georg von Hevesy Foundation of Nuclear Medicine in Zurich, Switzerland together with the president of the Second World Congress of Nuclear Medicine, Henry N.Wagner, Jr., have been the major forces in arranging publication of this book. The Georg von Hevesy Foundation is sponsoring the Hevesy Prize for Nuclear Medicine, the Hevesy Medal, and the Hevesy Memorial Lecture.