This book, now published in its second edition, covers a wide range of topics relating to the use of radiopharmaceuticals. The basics of nuclear chemistry, radiochemistry, and radiopharmacology are considered in detail, regulatory issues are reviewed, and potential applications in drug development, translational medicine, clinical diagnostics, and targeted therapy are discussed. Compared with the first edition, the chapters on targeted therapy with alpha- and beta-emitting radiopharmaceuticals and theranostics are completely new. Other chapters have been updated and revised as necessary. Radioisotope-based molecular imaging probes (radiopharmaceuticals) provide unprecedented insights into biochemistry and function in both normal and diseased states of living systems, with unbiased in vivo measurements of regional radiotracer activities offering very high specificity and sensitivity. No other molecular imaging technology, including functional magnetic resonance imaging, can provide such high sensitivity and specificity at a tracer level. This book, written by an experienced radiochemist and scientist, offers valuable insights into the full range of applications of this technology.