ERBB2 and neoplasm: The affibody labelling route exploited a C‐terminal selenocysteine tetrapeptide Sel‐Tag, that enabled site‐specific labelling using the common 11C‐labelling reagent, [11C]methyl iodide within 45 min (Scheme 8).53 This labelling method, using the shorter 11C half‐life, may be promising for the rapid and repeated monitoring of HER2 expression levels in tumours, and also for monitoring of responses to therapeutic treatment over time using lower doses of radioactivity.