This study aims to assess the validity of SUV, TPR and TBR against Patlak Ki for quantifying irreversible uptake of 89Zr-Immuno-PET studies in tumours, exemplified with two different datasets, one using 89Zr-anti-EGFR, which is cetuximab given with a fixed mass dose, and 89Zr-labelled anti-HER3 mAb (89Zr-anti-HER3), which is GSK2849330 administered with variable mass doses. This evidence concerns the gene ERBB3 and neoplasm.