A historical perspective on the specific activity of radiopharmaceuticals: what have we learned in the 35 years of the ISRC?

Specific activity (SA), defined as the amount of radioactivity per unit mass of a compound, is arguably one of the most important parameters in radiopharmaceutical development, particularly in quality control of carbon-11- and fluorine-18-labeled compounds. This review article will outline the progression of improvements in SA over the last few decades. The International Symposium of Radiopharmaceutical Chemistry abstracts were an excellent source of materials for this review and will be referenced throughout.