Positron-emission tomography (PET) is an important tool in cancer diagnostics since it allows virtually any biochemical process in the human body to be followed with positron-emitting radiotracers, injected in picomolar quantities (1). Radiotracers consist of a radioactive, positron-emitting isotope, linked to a biological tracer, targeting any biochemical process, receptor or any other druggable target (2). Isotopes suitable for PET imaging are proton-rich, such as 18F, 13N, 15O, 68Ga, 82Rb, or 89Zr and decay by emission of a neutron, a positron, and a neutrino. The emitted positron annihilates with a local electron after a short travel through matter (18F; ∼1 mm) with emission of two 511 keV gamma photons at 180° to each other.