Cerenkov luminescence images (A) and PET images (B) of six samples of 89Zr activity in water. 1–6 corresponded to activity concentrations of 40.3, 32.6, 27.4, 20.4, 13.3, and 0.00 kBq/mL. (C) Images of equal activities of F-18 samples (3.952 MBq, 20L) diluted in 2 mL of water (H2O, refractive index: n = 1.3359), ethanol (C2H5OH, n = 1.366), saltwater (H2O and saturating NaCl, n = 1.377) along with a control sample of water without radionuclide. (A) and (B) adapted with permission from Ruggiero et al.7 (C) Adapted with permission from Thorek et al.3