Consensus nomenclature rules for radiopharmaceutical chemistry — Setting the record straight

Abstract

Over recent years, within the community of radiopharmaceutical sciences, there has been an increased incidence of incorrect usage of established scientific terms and conventions, and even the emergence of 'self-invented' terms. In order to address these concerns, an international Working Group on 'Nomenclature in Radiopharmaceutical Chemistry and related areas' was established in 2015 to achieve clarification of terms and to generate consensus on the utilisation of a standardised nomenclature pertinent to the field. Upon open consultation, the following consensus guidelines were agreed, which aim to.

Chemical Kinetics of Radiolabelling Reactions

“…Current nomenclature rules and parameterd efinitions given in the consensus report by Coenen et al are used throughout. [23] By definition, the RCY is the amount of activity in the product expressed as a percentage (%) of the startinga ctivity used in the considered process (for example, synthesis, separation, etc. ), where both quantities refer to the same radionuclide, and are decay corrected to the same point in time before the calculation is performed.…”

“…Activity yield is defined as, "…the overall activity of ar adioactive product isolatedf rom the production of ar adiolabelledc ompound or radiopharmaceutical." [23] Activity yields are normally expressed in units of activity (Bq) butv alues can also be normalised to the initial activity and reported as ap er- It is important to note that the chemical yield and the activity yield differ when radioactived ecay is non-negligible during the process. Although high chemical yields are desirable,t he maximum activity yield does not necessarily coincide with peak chemical conversion.…”

Synthesis of [18F]Fluoroform with High Molar Activity

“…However, most of the strategies suffer from a fundamental issue: as the trifluoromethyl group is polyfluorinated, there is a high risk for isotopic dilution with fluorine‐19 caused by exchange processes between fluorine‐18 and fluorine‐19 . This results in low molar activities, defined as the amount of radioactivity per mol of compound . The molar activity should be as high as possible when targeting receptors with low density in order to guarantee preservation of the tracer principle i.e.…”

Reaction of 11C‐benzoyl chlorides with metalloid reagents: 11C‐labeling of benzyl alcohols, benzaldehydes, and phenyl ketones from [11C]CO

“…The vial was allowed to cool for 1 minute before piercing of the septa to release and determine any loss of gaseous radioactivity. In all reactions, >99% of the radioactivity was retained in the reaction vial after completed reaction, concluding that the [ 11 C]CO trapping efficiency was greater than 99% in all experiments . An aliquot was drawn from the crude reaction mixture and analyzed with radio‐HPLC to determine the non‐isolated RCY.…”