This book is a compilation of the invited papers, which were presented at the Fourth European Symposium on Radiopharmacy and Radiopharmaceuticals, which was held in Baden, Switz- land, 1-4 May, 1991. The First and Third Symposia on Radiopharmacy and Radiopharmaceuticals (Elsinore, Denmark, 1983, 1987) concentrated on the safety and efficacy of radiopharmaceuticals, whereas this Fourth Symposium to some extent followed up the subject of the Second...